Asphalt Modified Discussion

[ccracin]

I sent Ron Sutton a PM regarding some help I am trying to provide a friend that purchased my old Asphalt Modified some years ago. He thought it would be helpful to start a thread just in case anyone was interested in the discussion. So here we go. We have had quite a bit of instability with asphalt short track racing in southwestern PA for the last 5+ years I would say. Because of that and other reasons this car hasn't run much. With the start of 2014 both 1/2 mile tracks have been purchased by new owners and will be opened with full race schedules. It's not important to the discussion, but here is the car before I sold it. Everyone likes pictures!

http://i140.photobucket.com/albums/r35/ccracin/Racing/RCAR7.jpg (http://s140.photobucket.com/user/ccracin/media/Racing/RCAR7.jpg.html)

The current owners want to come back out and run a full season. In the years that have passed since I ran it the engine rules have changed to a point that the combination he has is not competitive. They are on a budget and can't go to one of the top builders in the area that have good packages. I want to try and point them in the right direction so that when they freshen their engine here in the next few weeks, they can make some changes for the better. As we all know tailoring an engine for it's intended purpose is a complex deal. I am quite sure we will not be able to go all out, but the discussion should be interesting. On to the details:

The rules the track currently uses are as follows. I trimmed them to just what applies to this car.
*Must be NASCAR recognized small block engines.
*Maximum engine displacement of 360 cid.
*Must be stock cast iron blocks with all standard internal and external
dimensions except the allowable maximum overbore.
*Steel crank and rods only.
*Minimum crankshaft weight 48 lbs.
*No modifications to the crankshaft counterweights.
*Crankshaft must be identical in construction and appearance as OEM crankshaft.
*Minimum rod journal size 2.100 minus .030.
*The stroke may not be increased or decreased.
*Pistons must be 3 ring grooves with 3 rings in place flat tops or dished.
*No portion of the piston may protrude above the top of the block.
*Crankshaft must be stock stroke for the engine size being used.
*Compression ratio may not exceed 10.8/1 as computed by the track KATECH whistler. NO TOLERANCE.
*No dry sump oiling permitted.
*Engines must be a minimum of 350 cid.
*No coatings on any internal engine parts including but not limited to ceramic.

*Cast iron stock heads only. No Vortec style or center mounted valve cover mounting stud - style permitted.
*General Motors may use GM #10134392 casting #14011034, GM
#3987376 casting #3991492, GM #12480034.
*General Motors may not use GM #12529093 casting #102339906
*All valves must remain identical to stock OEM for head being used.
*No porting, port matching, polishing, Hog Cutting or cleaning up of the
heads permitted.
*2 valves per cylinder.
*Only steel valves and valve springs permitted.
*Flat tappet cams and lifters ONLY
*No mushroom, roller, or oversized lifter permitted.
*Stud mounted roller rocker arms permitted, maximum 1.65to 1 ratio
*Listed below is the ONLY approved intake manifolds permitted.
*These manifolds must remain as manufactured. No porting, port matching, grinding or polishing permitted.
*Manifolds may not be painted.
*All part numbers are Edelbrock Performer Series intake manifolds:
1.Chevrolet-#2101
*Following is the ONLY approved carburetor:
1. Holley 2300 two-barrel 500 CFM carburetor, model #4412, including
the HP model.
(The rework guidelines dictate the carb should not be modified and pass all Holley gauge inspections.)
*ONLY a Moroso #64966 un-modified carburetor adapter permitted.
*Gaskets used between carb and adapter must be paper .065 inch maximum thickness.
*Maximum of two gaskets, carb to adapter to manifold permitted.
*Fuel must be race gasoline with no oxygen carrying additives. NO METHANOL.

I forgot to add, they also have to run a 6300rpm rev limiter chip

I know that was long and involved Ron, but better to have all the information. Their current combination requires new pistons, but they want to reuse their crank and rods. Crank is a stock 3.48" stroke chevy steel crank. I believe they have 6" I-Beam rods that are not considered light weight. I can ge the specs if needed. The areas that are open for improvement are pistons, heads, and cam. They have the intake and carb. Currently they have 492 heads with 2.02 and 1.6 valves. They worked well when we ran 350cfm carbs with restrictor plates. Now I think they can do better with 034 bow tie heads.

I'll quit now and hopefully you can give me some thoughts. Thanks very much for your time. I'm really excited to get my foot back in this circle a bit.

[ironworks]

Also looks like the carb is open for discussion.

There are some great rebuilders out the that will make the 4412 carb a true runner and worth 10hp. I noticed quite a difference in mine.

[ccracin]

Also looks like the carb is open for discussion.

There are some great rebuilders out the that will make the 4412 carb a true runner and worth 10hp. I noticed quite a difference in mine.

I agree, we had the same rules for the 350cfm carbs when I ran. I had 2 different "built" carbs and a box stock. Both Built carbs were worth 8+ hp with the restrictor plate, but more important the throttle response was dramatically improved. They may be willing to do something there. I want to give them a list of things that can be done, then it will be up to them as to what they can and want to do.

[Che70velle]

Chad, what combination is together, currently? Tell us what is there, and perhaps that would give us an idea of where they need to go.
I'd be inclined to say that there have probably been more advances in suspension technology, that should be addressed, that would make them quicker, than actual engine upgrades. I ran Lanier National Speedway, across from Road Atlanta, with our asphalt late models. It was a 3/8 mile low banked track, and my engine builder would constantly tell me to put my money in my chassis. He was always right.

[ccracin]

Chad, what combination is together, currently? Tell us what is there, and perhaps that would give us an idea of where they need to go.
I'd be inclined to say that there have probably been more advances in suspension technology, that should be addressed, that would make them quicker, than actual engine upgrades. I ran Lanier National Speedway, across from Road Atlanta, with our asphalt late models. It was a 3/8 mile low banked track, and my engine builder would constantly tell me to put my money in my chassis. He was always right.

I don't disagree with you at all about the chassis. I agree and can help them in that regard. There have definitely been changes in chassis technology since this car was built. Unfortunately only minor changes will be possible based on the budget from what I am being told. The few races he ran last year, he looked to be close with the chassis. Unfortunately they are changing tires on them again, so it will be back to testing there. He is definitely down on power. I truly believe this will be his best bang for the buck. A chassis guy always wants power and an engine guy says the car doesn't handle well enough. Thats why I like this helping out, I'm impartial! LOL

He is still running the combination of heads and cam I ran with a 350cfm 2 barrel and an 1.125" restrictor plate. There is no way this is adequate for a good 500 2bbl with no plate that I can see. He had all the tell tale sounds of lack of power last year when he ran. He could gain a car length coming out of the corner and lose 1.5-2 from the flagman to turn 1 on a half mile track. That deal was set-up to make torque and be run with a slightly higher gear to run at the end of the straight. Now the guys can put a lower gear in and have the legs to get to the end of the straight and hit the 6300 chip they are mandated to run.

[Ron Sutton]

Hi Chad,

The key to optimizing restricted engines is to not leave anything on the table & take nothing for granted. Every little bit matters. 10.8 compression is better than 10.7 ... 510 cfm is better than 500 cfm … a few ounces here & there … etc, etc.


A. The 034 bowtie head is the best of those options hands down. I think it flows around 215 cfm, which isn’t anything astounding but it’s the best cast iron GM SBC head.

B. A big deal in these engine is the getting the "squish band" to the optimum number of .035". This means "cold" the piston has .035" clearance to the head surface. This is achieved with a combination of head gasket thickness & block decking.

As an example,
If they run a .041" FelPro gasket, the piston needs to stick out of the block by .006" ... putting the top of the piston at .035” from the head.
If they run a .039" FelPro gasket, the piston needs to stick out of the block by .004" ... putting the top of the piston at .035” from the head.
If they run a .031” FelPro gasket, the piston needs to be down in the bore by .004” ... putting the top of the piston at .035” from the head.

While we’re on head gaskets, run the smallest diameter bore you can. If the engine bore is 4.040”, try to get a head gasket bore around 4.080”. To achieve the optimum squish band, you’ll need a gasket .035” or thinner to meet the "no piston above the deck rule". There are several around .031” See if you can get them with the 4.080” bore. That would be a good gasket for this app with the small 64cc chamber.

C. If the track doesn’t tech carbs with a gauge, there is 30 precious cfm with some TLC. If they do, see if they tech the butterfly shafts. Milling them is worth 10cfm. If the carb has to be 100% gauge legal, it still needs to be reworked.

D. K&N Filters designed a racing filter with a profiled top & bottom that flat out flows more air. Since every CFM matters, you’ll want to use the K&N “Flow Control System” on their 2-barrel. Run the 4.5” tall version & pick the correct one if the carb has the choke horn still on or not.

E. Too bad you can’t switch manifolds. The Edelbrock Victor Jr 2-BBl … is the best mid range Intake manifold I have found through testing. In fact, with our 587HP 2-barrel 410” engines, we went away from it to kill some mid-range (and gain upper end.) But it sounds like a performer it is. Do the rules allow you to run the air-gap version?

F. I see they do not allow methanol for fuel. What about E85 or “Ethanol”? If they allow E85/ethanol, that is your best choice by far. If they require it to be a certain percentage of ethanol, the best strategy is to mix Ethanol & racing gas. Ethanol will flat out build more top end power, so in the 4000-6300 rpm range they’re have an advanatge.

G. Back on the carb again, if they allow E85, I’ve got a guy I worked with that together we developed some good pieces.

H. Comp Cams has some new-ish solid lifter lobe profiles that have more area under the curve while still allowing standard .842” solid lifters. The mistake too many racers make on restricted engines is under-camming them. They think well there is less airflow, so I need to make all my power down low. This is not optimum. When these are the rules, the racer that builds the most total power under the usable rpm curve … and specifically the last 1500 rpm of powerband … will have a faster combination.

Two keys to cam selection is car handling & driving. If we have a poor handling set-up car that can’t carry as much mid-corner speed without pushing … or a driver that parks it in the corner … we can’t optimize the engine. We have to band-aid the engine to build more low end torque to get the turd out of the corner. So 3800 rpm matters more. On the other hand, if we have a well set-up car … with good front end geometry that allows higher mid-corner speeds … and the driver knows how to get optimum corner speed out of the set-up … we don’t have to worry about the very bottom of the rpm curve. We can build a rocket that is “good” at 4200 … but doesn’t blow the tires away … and is “mean” from 4700-6300.

I have three cams in mind, depending on how good you think they are with corner speed.

I. Header & exhaust design are critical here. For optimum power throughout the range, we need step headers & a crossover. Before I make any specific recommendations, I need to know what cam strategy we land on … and if there are any sound decibel limits we need to meet at the track(s) they run.

J. Gear ratio. If we build the “mean” engine that builds better power up top … and less power down around the corner exit rpm … we can run a step more gear in the rear. This is faster. A lot of guys think if two engines put out the same power at different RPM’s … then they can just gear the car to the power band & they will be equal. Not true.

K. Ignition timing will be more critical with the 10.8-1 compression. I’d start at 37° with this combo. Don’t mess around with advance curves. Ideally in race engines, you want to have full timing at idle. Just use a retard feature for starting it. For these engines I like the MSD E-Curve billet distributer. You can set it up to retard the timing 24° to start … then it goes to full timing at idle once the engine is running. It runs smoother, doesn’t load up, gets rolling easier, gets around the pits better, and handles low speed caution flags better.

If they can afford $200 to put the car on a chassis dyno, you can get the last 20hp of the engine by fine tuning the jetting & timing. Tune for optimum power from 4700-6300 & give up some in the 4000-4300 range so it doesn’t spin the tires easily. This allows the driver to roll the throttle on quicker and get the acceleration cycle started earlier. This is key both to good lap times, but also setting up passes. You can’t pas someone if you can’t get off the corner well enough to get along side them.

Dyno test the timing … up & down from 37° … and whatever timing builds most power from 4700-6300 will be your number. Make 2° changes at first, then fine tune it with 1° changes. 1° matters, especially in restricted race engines.

L. For oil, I strongly urge them to run a “blend” over full synthetic or full petroleum based oil. The “good” petroleum based oils offer better lubricity, for less wear, longer time between rebuilds & frankly more power over a longer period of time. The synthetic part of the blend offers a higher level of heat protection. Thicker viscosities add more friction. Super thin viscosities offer less protection. I’d like to see them run a 10w40 or 15w40 … depending on the rod & main bearing clearances. If you keep them .0015” - .0018” that would be my choice.

M. Blueprinting the oil pump is strongly suggested … or simply buying it that way. Getting the rotors deburred & the clearances optimized so the pump is “low drag” is the goal here. You don’t need a ton of volume or pressure in a SBC turning 6300 rpm. Buy a quality pump, but don’t get carried away with pressure or volume. Both are HP reducers.

O. There doesn’t seem to be a timing chain rule. At a minimum, go with the tru-roller from Cloyes with the index-able gears. If budget allows, I’ve seen better power & extended engine life with the Comp Cams belt drives.

P. I can’t say enough about making the rotational assembly light. If the crank rule is 48#, for Pete’s sake get down right to it. Target 48.5#.

Q. Several manufacturers offer light pistons. I think JE has them around 375 grams with standard pins.

R. An area not tech’ed is piston pins. This thing won’t build major power, so you can run thinner wall, light pins.

S. A little out of order, but whatever cam I recommend, they’re going to want 1.65 roller rockers.

T. With only 6300 rpm, they don’t need big ol’ pushrods. Here is an opportunity to go small diameter & thin wall chromoly & lighten the valvetrain. (Hardend tips.)

U. Spend the little extra for titanium valve spring retainers. They will pay for themselves plus some with extended life of the valvetrain.

V. Probably not a big issue, but make sure the valve springs are set-up close to coil bind to reduce oscillation & bounce. (Remember, the engine doesn’t make compression until the intake valve stops bouncing & actually seals. )

W. Once we land on a cam, valve spring pressure is critical. Too little & we have power loss along with durability issues.

X. Don’t cut corners on the valve guides or seals. We need it sealed with as close to zero oil contamination in the cylinder as possible. Some people justify the cylinder need lubrication, but the low tension oil rings already take care of that.

Y. If we end up on gasoline, run as cold of a plug as possible, like a 1 on an Autolite scale or a 10 on an NGK scale & dial in the jetting & timing. If we run Ethanol, run 1 step hotter … like a 2 on an Autolite scale or a 9 on an NGK scale. Stay away from the trick of week 2, 3, 4 or 987 prong spark plugs. I buy $3 race plugs so I can read them & throw them away. Buy plugs with the strap cut back or cut it back yourself. Gap them at .035" & index it so the gap opening is pointing straight down to the top of the piston or just slightly towards the intake valve.

Z. Frankly, an ignition amplifier won’t build any more power here unless the jetting is too rich. But make sure they have a top notch coil 7 new wires. Replace the wires every season. Don’t wait for them to “go bad.”

Get me answers to my few questions above & we’ll get working on cam & exhaust.

[ccracin]

Can I just first say, I LOVE THIS STUFF! Ok, here we go:

Hi Chad,

The key to optimizing restricted engines is to not leave anything on the table & take nothing for granted. Every little bit matters. 10.8 compression is better than 10.7 ... 510 cfm is better than 500 cfm … a few ounces here & there … etc, etc.


A. The 034 bowtie head is the best of those options hands down. I think it flows around 215 cfm, which isn’t anything astounding but it’s the best cast iron GM SBC head.

B. A big deal in these engine is the getting the "squish band" to the optimum number of .035". This means "cold" the piston has .035" clearance to the head surface. This is achieved with a combination of head gasket thickness & block decking.

As an example,
If they run a .041" FelPro gasket, the piston needs to stick out of the block by .006" ... putting the top of the piston at .035” from the head.
If they run a .039" FelPro gasket, the piston needs to stick out of the block by .004" ... putting the top of the piston at .035” from the head.
If they run a .031” FelPro gasket, the piston needs to be down in the bore by .004” ... putting the top of the piston at .035” from the head.

While we’re on head gaskets, run the smallest diameter bore you can. If the engine bore is 4.040”, try to get a head gasket bore around 4.080”. To achieve the optimum squish band, you’ll need a gasket .035” or thinner to meet the "no piston above the deck rule". There are several around .031” See if you can get them with the 4.080” bore. That would be a good gasket for this app with the small 64cc chamber. When I was running we had a 10.5:1 rule and I ran zero deck with a .035 steel shim gasket, so I had this in mind

C. If the track doesn’t tech carbs with a gauge, there is 30 precious cfm with some TLC. If they do, see if they tech the butterfly shafts. Milling them is worth 10cfm. If the carb has to be 100% gauge legal, it still needs to be reworked. They have a No-Go for the throttle shaft and plate combo, I will try to get that size and see if there is anything we can gain there.

D. K&N Filters designed a racing filter with a profiled top & bottom that flat out flows more air. Since every CFM matters, you’ll want to use the K&N “Flow Control System” on their 2-barrel. Run the 4.5” tall version & pick the correct one if the carb has the choke horn still on or not.Believe it or not they have outlawed that filter housing. you can run a 3x14 K&N element but that's it. No flow control devices at all. The best we can do is the spun aluminum setup from Speedway with the o-ring seal.

E. Too bad you can’t switch manifolds. The Edelbrock Victor Jr 2-BBl … is the best mid range Intake manifold I have found through testing. In fact, with our 587HP 2-barrel 410” engines, we went away from it to kill some mid-range (and gain upper end.) But it sounds like a performer it is. Do the rules allow you to run the air-gap version? Negative on the air-gap. 2101 only.

F. I see they do not allow methanol for fuel. What about E85 or “Ethanol”? If they allow E85/ethanol, that is your best choice by far. If they require it to be a certain percentage of ethanol, the best strategy is to mix Ethanol & racing gas. Ethanol will flat out build more top end power, so in the 4000-6300 rpm range they’re have an advanatge.No alchohol or E85. Must by fuel at the track. VP 110 They will do a specific gravity test.

G. Back on the carb again, if they allow E85, I’ve got a guy I worked with that together we developed some good pieces. Ugh

H. Comp Cams has some new-ish solid lifter lobe profiles that have more area under the curve while still allowing standard .842” solid lifters. The mistake too many racers make on restricted engines is under-camming them. They think well there is less airflow, so I need to make all my power down low. This is not optimum. When these are the rules, the racer that builds the most total power under the usable rpm curve … and specifically the last 1500 rpm of powerband … will have a faster combination.I ran a custom Comp Cam that used the MA Solid Flat Tappet Lobes for .842 lifters. I gave the cam card to them, but I believe it was the 244/248 at .050 on 115 deg. center line. It ran very well with the combo I had.

Two keys to cam selection is car handling & driving. If we have a poor handling set-up car that can’t carry as much mid-corner speed without pushing … or a driver that parks it in the corner … we can’t optimize the engine. We have to band-aid the engine to build more low end torque to get the turd out of the corner. So 3800 rpm matters more. On the other hand, if we have a well set-up car … with good front end geometry that allows higher mid-corner speeds … and the driver knows how to get optimum corner speed out of the set-up … we don’t have to worry about the very bottom of the rpm curve. We can build a rocket that is “good” at 4200 … but doesn’t blow the tires away … and is “mean” from 4700-6300. I'm not sure where he will be honestly. Once he learned the tires, he ran well through the corner. Once I convinced him to use the brake and throttle together in the corner rather than using the engine to brake in the corner he picked up a lot of time. They now have another new tire, the Hoosier Commanche. In my opinion he has the capability of getting there. I would shoot for "maybe" to "mean" from 4700-6300. Make sense?

I have three cams in mind, depending on how good you think they are with corner speed.

I. Header & exhaust design are critical here. For optimum power throughout the range, we need step headers & a crossover. Before I make any specific recommendations, I need to know what cam strategy we land on … and if there are any sound decibel limits we need to meet at the track(s) they run. Sound Limits are 100db at 100 feet. I know he doesn't run crossovers. I did, but he didn't want to pay for the exhaust system when I sold the car. My system was Howe crossovers, 1 5/8" stepped to 1 3/4" with 3" collectors and a 3' to 3" Y and 3" Dynomax Bullet Muffler It worked very well.

J. Gear ratio. If we build the “mean” engine that builds better power up top … and less power down around the corner exit rpm … we can run a step more gear in the rear. This is faster. A lot of guys think if two engines put out the same power at different RPM’s … then they can just gear the car to the power band & they will be equal. Not true. Agreed. The top cars are running a 4.86 and hitting the chip just as they lift for the corner. Although we will have to see what the tire sizes will be as compared to last year to verify this will remain the same. When he ran last year he was topping out between 6 and 6100

K. Ignition timing will be more critical with the 10.8-1 compression. I’d start at 37° with this combo. Don’t mess around with advance curves. Ideally in race engines, you want to have full timing at idle. Just use a retard feature for starting it. For these engines I like the MSD E-Curve billet distributer. You can set it up to retard the timing 24° to start … then it goes to full timing at idle once the engine is running. It runs smoother, doesn’t load up, gets rolling easier, gets around the pits better, and handles low speed caution flags better. The rules state "No electronic timing controls" not sure if this distributor falls in this category.

[ccracin]

[B] If they can afford $200 to put the car on a chassis dyno, you can get the last 20hp of the engine by fine tuning the jetting & timing. Tune for optimum power from 4700-6300 & give up some in the 4000-4300 range so it doesn’t spin the tires easily. This allows the driver to roll the throttle on quicker and get the acceleration cycle started earlier. This is key both to good lap times, but also setting up passes. You can’t pas someone if you can’t get off the corner well enough to get along side them.

Dyno test the timing … up & down from 37° … and whatever timing builds most power from 4700-6300 will be your number. Make 2° changes at first, then fine tune it with 1° changes. 1° matters, especially in restricted race engines. I will definitely suggest this to them.

L. For oil, I strongly urge them to run a “blend” over full synthetic or full petroleum based oil. The “good” petroleum based oils offer better lubricity, for less wear, longer time between rebuilds & frankly more power over a longer period of time. The synthetic part of the blend offers a higher level of heat protection. Thicker viscosities add more friction. Super thin viscosities offer less protection. I’d like to see them run a 10w40 or 15w40 … depending on the rod & main bearing clearances. If you keep them .0015” - .0018” that would be my choice. Again, I will pass this along

M. Blueprinting the oil pump is strongly suggested … or simply buying it that way. Getting the rotors deburred & the clearances optimized so the pump is “low drag” is the goal here. You don’t need a ton of volume or pressure in a SBC turning 6300 rpm. Buy a quality pump, but don’t get carried away with pressure or volume. Both are HP reducers. Do you have a prefered source and or part number. They will be buying a new pump anyway, I'm sure.

O. There doesn’t seem to be a timing chain rule. At a minimum, go with the tru-roller from Cloyes with the index-able gears. If budget allows, I’ve seen better power & extended engine life with the Comp Cams belt drives. They are currently running the Cloyes Hex Adjust that was on the engine I sold them.

P. I can’t say enough about making the rotational assembly light. If the crank rule is 48#, for Pete’s sake get down right to it. Target 48.5#. I told them this already. Since they are replacing pistons, I told them this can be done if it hasn't already when they have the rotating assembly balanced

Q. Several manufacturers offer light pistons. I think JE has them around 375 grams with standard pins. Already suggested

R. An area not tech’ed is piston pins. This thing won’t build major power, so you can run thinner wall, light pins.Already suggested

S. A little out of order, but whatever cam I recommend, they’re going to want 1.65 roller rockers. I ran Comp Cams Magnum Rockers, but again in saving money, the went will aluminum rollers, not sure of brand. Do you have a preference?

T. With only 6300 rpm, they don’t need big ol’ pushrods. Here is an opportunity to go small diameter & thin wall chromoly & lighten the valvetrain. (Hardend tips.)That's what they had when they got it from me. I will make sure they replace them. You may be confused with some of this. They spun a couple bearings in the motor they got from me. I think due to a water leak, but has not been confirmed. LOL so they transferred the top end to another short block.

U. Spend the little extra for titanium valve spring retainers. They will pay for themselves plus some with extended life of the valvetrain.

V. Probably not a big issue, but make sure the valve springs are set-up close to coil bind to reduce oscillation & bounce. (Remember, the engine doesn’t make compression until the intake valve stops bouncing & actually seals. )

W. Once we land on a cam, valve spring pressure is critical. Too little & we have power loss along with durability issues.

X. Don’t cut corners on the valve guides or seals. We need it sealed with as close to zero oil contamination in the cylinder as possible. Some people justify the cylinder need lubrication, but the low tension oil rings already take care of that.

Y. If we end up on gasoline, run as cold of a plug as possible, like a 1 on an Autolite scale or a 10 on an NGK scale & dial in the jetting & timing. If we run Ethanol, run 1 step hotter … like a 2 on an Autolite scale or a 9 on an NGK scale. Stay away from the trick of week 2, 3, 4 or 987 prong spark plugs. I buy $3 race plugs so I can read them & throw them away. Buy plugs with the strap cut back or cut it back yourself. Gap them at .035" & index it so the gap opening is pointing straight down to the top of the piston or just slightly towards the intake valve.

Z. Frankly, an ignition amplifier won’t build any more power here unless the jetting is too rich. But make sure they have a top notch coil 7 new wires. Replace the wires every season. Don’t wait for them to “go bad.”

Get me answers to my few questions above & we’ll get working on cam & exhaust.



Hopefully I have given you what you need. I plan on taking the results of this discussion and putting together an outline for this engine. I will then pass it along and hope hope hope they work to it.

Later I would like to discuss this car's front end as well as another friend's I help. This car is a Dirtworks Asphalt car Bart Bates built. The other car I help with is an Ellis. I think you are familiar! But that's another topic!

The post had too many characters so I had to split it. In hind site, i should have just refereed to the letters. Next go around!

[Ron Sutton]

Hopefully I have given you what you need. I plan on taking the results of this discussion and putting together an outline for this engine. I will then pass it along and hope hope hope they work to it.

Later I would like to discuss this car's front end as well as another friend's I help. This car is a Dirtworks Asphalt car Bart Bates built. The other car I help with is an Ellis. I think you are familiar! But that's another topic!

The post had too many characters so I had to split it. In hind site, i should have just refereed to the letters. Next go around!

Yes you have. I think the middle of the three cam options makes sense. Let me play with some cam & exhaust combos & I'll post a package & simulated dyno graph up this weekend.

[ccracin]

Just checking in Ron. Did you go to speedweeks this year?

[Ron Sutton]

Just checking in Ron. Did you go to speedweeks this year?

Sorry about that Chad. My girls had 3 days off & took me to the snow. Have you ever seen a fat boy sled down a steep mountain side? :confused59:

I'm just heard back from my guy at Comp Cams, so I'll post up the details today.

[Ron Sutton]

Hey Chad,

First, everything I'm recommending is based off of 1.65 roller rockers (Crower stainless are my recommendation by far).

-----------------------------------------------------------------------

If the timeline requires an "off the shelf" camshaft, I recommend:
Comp Cams Grind: 286XOS
* Careful, there are two versions - Get PN: 12-657-5

Duration @ .050: Int=256° Exh=262°
106° LSA (Lobe Separation Angle)
Install this cam at 6° advanced

Lobe lift: Int=366" Exh=.362"
Valve lift with 1.65 Rockers: Int=604" Exh=.597"
* Actually slightly different with hot lash calculated in.

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But what it really needs is a custom grind. Same price, just takes a while longer to get.

The cam profile I recommend includes the intake lobe profile from the cam above ... 286XOS ... and the exhaust lobe profile from the 290XOS ... with a wider LSA at 108°.

The specs would look like this:

Duration @ .050: Int=256° Exh=266°
108° LSA (Lobe Separation Angle)
Install this cam at 6° advanced

Lobe lift: Int=366" Exh=.366"
Valve lift with 1.65 Rockers: Int=604" Exh=.604"
* Actually slightly different with hot lash calculated in.

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With either cam at 6° advance, you may need to flycut the intake valve pocket on the piston a bit more. Maybe not. Ideally, you want .090" on the intake & .110" on the exhaust.

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More tips:
a. You do need to run the carb spacer they allow.
b. Run gapless piston rings (to get all the dynamic compression possible) with a low tension oil ring (for less parasitic loss).
c. The exhaust will be critical to maximum power. I'll map it out next & make a separate post.

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This dyno curve shows the off-the-shelf cam & the custom cam. The difference from 5250 rpm & up is key to a fast race car down the straights. This is the middle of the 3 cam profiles I was considering.

It will not be a torque monster. But it won't be lame either. the key to being fast with this combo is to gear the car to hit the 6300 rpm rev limiter 4-6' before the lift point.

The throttle won't be as sensitive. The car won't be edgy on exit about tire spin. The driver won't have to egg-shell the throttle. The driver will be able to roll the throttle on early & rapidly ... starting the acceleration ramp earlier.

From corner exit to the the next turn, it will be the best combo, if geared correctly.

[ccracin]

Sorry about that Chad. My girls had 3 days off & took me to the snow. Have you ever seen a fat boy sled down a steep mountain side? :confused59:

I'm just heard back from my guy at Comp Cams, so I'll post up the details today.



Every time I go sledding with my girls! :hello:

Coming down the hill is fun, hauling me, my sled, and their 2 sleds back up the hill is the issue! :waveflag:

No apologies necessary, i'll never argue over time with the family. I have my twins to chase around as well.

You went to the snow and I am desperately trying to get away from it!

I appreciate the time, I'm anxious just from curiosity. I don't have any skin in the game, but my friend that owns the cars texted last night to see where I was with it. He's ready to go. LOL Daytona has him all revved up!

[Ron Sutton]

Ok, the exhaust is critical. Can't stress that enough.

If they can find, or afford to have built, a 4-2-1 header set-up, that would be optimum. I'd be happy to map a system out for you. But I suspect not, so I've outlined a 4-1 exhaust system.

The headers need to be "Step headers" starting with a 1-5/8" primaries out of the head & stepping up to 1-3/4". 34"-36" long primary tubes.

FYI: All the dimensions after the primary header tubes ... are measured from the end of the primary tubes up inside the collector.

The collector needs to be 3" in diameter ... with a true "merge collector" diameter of 2-1/2" installed at 9.9"± from the end of the primary tubes. People often confuse collectors with merge collectors because the names are similar. A true merge collector necks down at a specific point & then necks back up. See the attached photos.

If the merge collector is designed correctly ...
* The 4 tubes come into the necked down area of the collector at a 10° to 15° angle
* There is a "merge tip" at the end of the primary header tubes, in the middle of the 4 tubes, that comes to a point.
* The collector necks down & then necks back up, forming a venturi.

I like, use & recommend Dynatech merge collectors & headers. They have the best "affordable" merge collectors. There are places that build merge collectors costing insane money that work about the same as the lesser expensive Dynatech versions. Warning: There are a lot of inferior designs that cost the same & even more.

For this application, the centerline of that venturi neck down needs to be at 9.9"± from the end of the primary header tubes.

The front edge of the opening of the H-pipe needs to be at 19.8"± from the end of the primary tubes. This one is very sensitive. Don't vary more than a half inch at most. Less is better.

The X-pipe (photo at bottom right) needs to be centered at 39.6"± from the end of the primary tubes. This one is less sensitive ... and inch or two either direction is ok.

The mufflers need to be centered at 79.2"± from the end of the primary tubes if possible. This is getting close to the suspension. If this won't work, they may need to eliminate the X-pipe & place the mufflers at 39.6"±. Unless they're running a "straight through" type of muffler, then placement is a non-issue.

If you need to vary from these dimensions, don't vary much, as you are upsetting the exhaust pulse timing. If you need to vary a lot ... let's talk first. It is better to have no H-pipe or X-pipe ... then to have them in the opposite location from optimum.

[Che70velle]

Good stuff Ron.

[ccracin]

Ok, Ron, I have taken it all in. This is great information. I am going to recommend the custom cam. I hope they can get it in time. This is what I came up with for the part and grind number of the cam you suggested. I got this from the master lobe catalog.

Part# 12-000-5
Grind # CS 6263/6414-S108

With regard to the exhaust, I am not sure they will be able to go this route at first. I will find out what they have now. I know it is not a crossover system. I think if I can get them to do most of this on the engine, the budget may take a beating. What do you think we can get away with at a bare minimum?

How about the carb? Anything I should tell them to pay attention to? I would can provide here will be greatly appreciated.

Do you have a recommended vendor for a blue printed oil pump?

They are not allowed the E-Curve Dizzy. Any options there?

Thanks.

[Ron Sutton]

Ok, Ron, I have taken it all in. This is great information. I am going to recommend the custom cam. I hope they can get it in time. This is what I came up with for the part and grind number of the cam you suggested. I got this from the master lobe catalog.

Part# 12-000-5
Grind # CS 6263/6414-S108

With regard to the exhaust, I am not sure they will be able to go this route at first. I will find out what they have now. I know it is not a crossover system. I think if I can get them to do most of this on the engine, the budget may take a beating. What do you think we can get away with at a bare minimum?
I probably should know what they have first. So find out & list it on here. If they can't afford step-headers, they need to go with the 1-3/4" straight headers. If they run 1-5/8" primaries the cam & headers will be working against each other. Just know they are giving up some low end power with 1-3/4" straight versus 1-5/8"-to-1-3/4" step headers.

An less expensive alternative to true merge collectors are "Insertable Collector Reducers". (Photo at bottom of page)

They basically slide into the 3" collector material & run a few welds to hold it in place centered at 9.9" from the end of the primary tubes. I've used them with some positive results when the exhaust was too tight to fit a merge collector in there.

An H-pipe is dirt cheap. It is the same 3" tubing as the exhaust. When I re-read my initial exhaust post #4 ... I saw I worded it incorrectly & went back to change it. (The corrections/additions are in red) You want to weld the H-pipe in so the leading edge of the H-pipe is at 19.8".

The rest of the exhaust needs to be 3" too. If it's smaller, that will not work with this cam cambo.



How about the carb? Anything I should tell them to pay attention to? I would can provide here will be greatly appreciated.
I can't tell you what the specs need to be, but the carb is critical in two areas. Obviously, ANYTHING that can be done legally to increase airflow is a priority. Get with a proven carb guy known for building good gauge legal GAS 2-barrels.

The second part if getting the fuel curve correct. This is all internal with orfices & bleeeds. How we do this is running the exact engine on the dyno for 12-20 hours with the carb guy tweaking the curve & making runs until the fuel curve, idle quality, throttle response & power are optimum. The challenge is they can't afford to do this. So they just need to get with that proven gas 2-barrel carb guy & trust his work.


Do you have a recommended vendor for a blue printed oil pump?
The Melling Select pumps are pretty good out of the box, but being frank, we still disassemble them, check for imperfections & deburr them. Precision Oil Pumps blueprints Melling select oil pumps & offers them ready to go for what I think is a pretty good price. Their website is here (http://stores.precisionoilpumps.com/oil-system-components/).

They are not allowed the E-Curve Dizzy. Any options there?
I did not see a distributor rule. If you can run any MSD billet racing distributor, that would be my pick. They have hardened shafts & 2 shaft bearings. There are other brands too.

But if they require OEM distributors ... I assume they allow you to run HEI distributors. Performance Distributors offers their "DUI" distributor ... which is basically a HEI clone ... with the best HEI distributor parts (coil, pickup, caps, rotors, etc.)

I have mixed feelings here. Where rules allow any distributor ... and where there are no rules ... I wouldn't run the DUI distributor because there are much superior options for literally a few dollars more.

I have ran the DUI distributor a LOT and get good performance out them ... especially 7000 rpm & below. My qualm with them is the fast wear rate of the non hardened shafts. I had to rebuild the DUI distributors every season & put in new shafts. Otherwise the shaft "wobbles" and timing is erratic.

So DUI is the best option if you can not run a racing distributor. Be prepared to rebuild with new shafts every off season.

As far as the timing curve ... run biggest weights & softest springs so the timing curve is extremely quick. Set the total timing at 37° to start & tune from there.


Thanks.

You're welcome.

[ccracin]

Ron,

Let's start with the distributor. There is no distributor rule per say, but there is a rule that does not allow electronic timing control or retard boxes. That's why I said I didn't believe the E-Curve dizzy would be allowed. I understand the goal here and will help them come up with a solution that best fits the budget.

With regard to the exhaust, here is what they have. The headers are Shoenfeld stepped but are not crossovers. They are 1 5/8" primary tubes stepped to 1 3/4". The 1 5/8" tubes are 16" long with a total tube length of 38 1/2". They have standard 4 into one 3" collector about 8" long then into the Sheonfeld slip on mufflers. They are 3' in and out with 3 1/2" bodies. They are mounted right to the end of the collectors.

Thoughts?

Thanks!

[Ron Sutton]

Hey Chad,

Ron,

Let's start with the distributor. There is no distributor rule per say, but there is a rule that does not allow electronic timing control or retard boxes. That's why I said I didn't believe the E-Curve dizzy would be allowed. I understand the goal here and will help them come up with a solution that best fits the budget.
OK. Got it. Get a "self contained racing distributor" that doesn't require an external controller or amplifier ... with a sealed bearing that the shaft spins on. MSD makes them as well as Accel & Mallory.


With regard to the exhaust, here is what they have. The headers are Shoenfeld stepped but are not crossovers.
Crossover not needed.

They are 1 5/8" primary tubes stepped to 1 3/4". The 1 5/8" tubes are 16" long with a total tube length of 38 1/2". They have standard 4 into one 3" collector about 8" long then into the Sheonfeld slip on mufflers. They are 3' in and out with 3 1/2" bodies. They are mounted right to the end of the collectors.

Thoughts?

Thanks!

The easy, low budget solution is ...
a. Keep the headers.

b. Use 3" exhaust tubing for the dual exhaust.

c. Place the center of Insertable Collector Reducers with 2.5" ID at 9.9" from the end of the primary tubes.

d. Add a H-pipe inbetween the dual exhaust with the front edge of the opening of the H-pipe 19.8"± from the end of the primary tubes.

For anyone following along with us, how we place "straight through" mufflers in the exhaust system is different than how we place mufflers with chambers. "Straight through" mufflers act much like straight exhaust tubing, so the placement isn't critical. Chamber mufflers are different, as the exhaust gases are traveling further ... and in some chamber muffler designs ... there is expansion.

e. Chad, since they have straight through type mufflers, attach the mufflers after the H-pipe & try to keep the end of the mufflers (where the exhaust exits into the air) around 37-43" from the end of the primary tubes.

[ccracin]

So I have a quick update for you Ron. I think what you have helped me with here is going to work out better than I even imagined. So, I took all the information from the thread and typed up basically an outline for them starting with the block and moving on. I sent it over to them and let them chew on it. They are both professional mechanics and own a garage, but they are not engine guys. I think what really hit home was how many details need to be addressed to really make the most of the rules. I told them they could go one of 2 ways. I would help them execute this plan and try to stay on budget. The other was I would get them in touch with the guy I think makes the best power in our area for these types of engines and they can say the hell with the budget and put a hammer in the car. They asked for the introduction and dropped their engine off at his shop today! LOL I'll keep you posted on the progress. Thanks very much!

You have me wanting to take the parts I have around the shop and putting a motor together to sell. It might be easier to clean the shop up that way!

[Ron Sutton]

Hi Chad,

So I have a quick update for you Ron. I think what you have helped me with here is going to work out better than I even imagined. So, I took all the information from the thread and typed up basically an outline for them starting with the block and moving on. I sent it over to them and let them chew on it. They are both professional mechanics and own a garage, but they are not engine guys. I think what really hit home was how many details need to be addressed to really make the most of the rules. I told them they could go one of 2 ways. I would help them execute this plan and try to stay on budget. The other was I would get them in touch with the guy I think makes the best power in our area for these types of engines and they can say the hell with the budget and put a hammer in the car. They asked for the introduction and dropped their engine off at his shop today! LOL I'll keep you posted on the progress. Thanks very much!
Too funny! But an excellent choice for them.


You have me wanting to take the parts I have around the shop and putting a motor together to sell. It might be easier to clean the shop up that way!

Haha. :lol:

[ccracin]

Well Ron, here is a quick update. They got the new engine and have more power than they ever have. Now they don't have the chassis to work with it. I warned them this was going to happen. I'm trying as much as I can to help them get close. One issue they are having is brakes. When I ran, we had to run OEM calipers and Pads. Now they can run racing pads but still have to run OEM calipers. This car has 12" 5x5 impala rotors and calipers on the front. Type 52. The rears are metric calipers on a floater. Type 154. What brake pads do you recommend for a 1/2 mile track? I was thinking a Hawk Blue or Black. I would appreciate your thoughts. Thanks!

[Ron Sutton]

Well Ron, here is a quick update. They got the new engine and have more power than they ever have. Now they don't have the chassis to work with it. I warned them this was going to happen. I'm trying as much as I can to help them get close. One issue they are having is brakes. When I ran, we had to run OEM calipers and Pads. Now they can run racing pads but still have to run OEM calipers. This car has 12" 5x5 impala rotors and calipers on the front. Type 52. The rears are metric calipers on a floater. Type 154. What brake pads do you recommend for a 1/2 mile track? I was thinking a Hawk Blue or Black. I would appreciate your thoughts. Thanks!

Hi Chad,

The brake pads depend on the suspension set up. If they were on a high travel/low roll set ... which I doubt they are ... they would need less aggressive pads. We ran Wilwood BP-10's on our High travel Modifieds, because we needed to brake moderately for a set distance without overslowing the mid corner.

In a conventional suspension set-up, you can drive it in deeper but have to slow it down more before mid corner, so you need a more aggressive pad. Most of my customers on Conventional suspension set-ups like the Hawk Blacks. But my one client that has the best conventional set-up (close to a tweener) drives in straighter, diamonds the middle & drives off straighter ... has a shorter braking zone & runs Hawk Blues.

That's why I feel brake pads need to fit the driver & car set-up.

:cheers: