Rhoads Variable Lifters. . .Auto-X/Road Racing???

[atomicjoe23]

Has anyone used Rhoads Variable lifters for Auto-X or Road Racing???

Thoughts, experiences???

I've got a '67 Firebird with a 400 that I'm doing some top end upgrades too and just read about these in the "Building Max Performance Pontiac Engines" book. . .that book is geared towards drag racing so I was wondering if they would be beneficial for Auto-X or Road racing. . .sounds like they might be.

Thanks for the help!

[Vegas69]

My gut tells me no. Drag racing lasts 15 seconds. Road racing lasts 20 minutes. I wouldn't want them in a sustained high rpm application.

[Panteracer]

Used them on several autocross motors... seemed to do ok
I think the new roller lifters are a better thing now

I would also look at what pan you have as I have had
no luck with any that say it is a road race style
Accumlator is the only way I am able to keep the oil
pressure up in a Pontiac motor while hitting the turns hard
Spun many a bearing in the Pontiacs in the past

Bob with an MR-1 494 CV-1 headed Pontiac now

[atomicjoe23]

Thanks Panteracer. . .I heard back from Jack Rhoads as well and he said they are successfully used in auto-X and road racing applications. . .

[GregWeld]

I don't understand why you'd want to use these. Today's roller cams offer so much more power and drivability. The need for Rhoad's lifters as a bandaid for too much cam on the street is so "yesterday".

[atomicjoe23]

That's why I'm asking GregWeld. . .trying to figure out what is out there and current for Pontiac engines for this type of application. . .

[GregWeld]

That's why I'm asking GregWeld. . .trying to figure out what is out there and current for Pontiac engines for this type of application. . .



I totally get it.... and it's a very good question. I looked into them years ago when big street cams were de rigueur. I should have looked at my response so that it didn't sound like I was saying WTF are you thinking! I didn't mean it that way --- I was really just saying that these days with the right roller cam - you can make crazy power and be totally streetable. This is something that wasn't possible to do back when the Rhoads lifters were invented.

[Ron Sutton]

I agree with Greg.

I ran Rhoads lifters back in the 70's & 80's on street engines we built to build a wider powerband into the engine. The lifter low-rpm bleed off allowed you to run a bigger duration cam. At Idle, the lifters bleed off so much, the engine effectively had much less cam duration. This bleed off reduced as you revved the engine up to 3000 RPM & after that acted just like a regular hydraulic lifter ... so the bigger duration built more power up top. They worked very well & were a nice little trick to broaden the powerband.

Technology today has surpassed that. The hydraulic roller lifters allow for much steeper camshaft ramp angles than can be run with conventional "Flat/Sharp Edge" solid or hydraulic lifters. So now, the duration can be small for bottom end ... but the steeper ramps allow for much more area under the lift curve ... so more power in the mid to upper RPM range ... even with shorter duration numbers.

You could say both of these strategies do the same thing, but different ways. But in reality, the gains from the hydraulic roller lifter far outweigh the gains from the Rhoads variable duration hydraulic lifter.

:cheers:

.

[atomicjoe23]

So are hydraulic roller lifters an option then. . .I thought that Pontiac engines required modifications to run roller lifters. . .

. . .I just finished reading "How to Build Max-Performance Pontiac V-8's" and they didn't recommend hydraulic roller lifters for Pontiac engines. . .granted that book is more focused on drag racing, but it does talk about balanced, streetable performance.

If hydraulic roller lifters are an option what lifters and cam would you guys recommend for a mild 400 (at the moment anyway, I would like to increase the displacement with an upgraded rotating assembly after I get the suspension/brakes where I want them).

Thanks for the help!

[Ron Sutton]

What cylinder heads do you have?

[atomicjoe23]

Ron,

I will verify what heads I have tonight hopefully. . .I need to find the part number on the Holley carb as well to either rebuild or replace it.

They are currently the stock iron heads for a '67 Firebird, but I know that doesn't completely narrow it down.

[Ron Sutton]

Ron,

I will verify what heads I have tonight hopefully. . .I need to find the part number on the Holley carb as well to either rebuild or replace it.

They are currently the stock iron heads for a '67 Firebird, but I know that doesn't completely narrow it down.

All I need is the 2 or 3 digits cast into the top of 2 center exhaust ports ... and whether or not you have ported them.

[atomicjoe23]

I have not ported them. . .I don't know if they were ported by a previous owner or not. . .although I doubt it.

It still has the original intake manifold on it. . .appears that headers and a Holley carb are the only performance mods made to the car before I got it.

[Later-A-Body]

Rhoads lifters work very well on the Pontiac motor. I have used them in the past with great results. Read some literature written by Jim Hand regarding these used in a street driven 4000 pound '71 Pontiac "GTO" station wagon that was used for testing many Pontiac parts. The car was consistently faster and much more streetable with the Rhoads lifters installed. They used the factory RAIV cam as a test base in a mildly modified 455. If you are not wanting to spend extra money to step up to a roller valvetrain, then the Rhoads would be a very good choice especially in a 400. They may have been designed 30 years ago, but they work just as well now as they did back in the day. I cant see why they wouldn't work in an autocross application. You want more throttle response and torque coming out of the corners. If you haven't spoke to a Pontiac expert, I would highly recommend calling SD Performance, Kaufmann Racing, or Butler Performance for all your options.

[Ron Sutton]

I have not ported them. . .I don't know if they were ported by a previous owner or not. . .although I doubt it.

It still has the original intake manifold on it. . .appears that headers and a Holley carb are the only performance mods made to the car before I got it.

All I need is the 2 or 3 digits cast into the top of 2 center exhaust ports.

[GregWeld]

It's not that they "don't work" -- they do what they're advertised to do.... What we're saying is that these days there are fantastic alternatives that didn't exist when the Rhoads lifter came to be. Today's cam profiles offer
exceptional road manners and great power.

I agree - a roller cam/lifters are more expensive than a flat tappet cam/lifters... but there are huge benefits.




Rhoads lifters work very well on the Pontiac motor. I have used them in the past with great results. Read some literature written by Jim Hand regarding these used in a street driven 4000 pound '71 Pontiac "GTO" station wagon that was used for testing many Pontiac parts. The car was consistently faster and much more streetable with the Rhoads lifters installed. They used the factory RAIV cam as a test base in a mildly modified 455. If you are not wanting to spend extra money to step up to a roller valvetrain, then the Rhoads would be a very good choice especially in a 400. They may have been designed 30 years ago, but they work just as well now as they did back in the day. I cant see why they wouldn't work in an autocross application. You want more throttle response and torque coming out of the corners. If you haven't spoke to a Pontiac expert, I would highly recommend calling SD Performance, Kaufmann Racing, or Butler Performance for all your options.

[atomicjoe23]

Ron,

I am going to TRY to remember to look at the heads tonight. . .it's been very hectic over here (as I'm sure it has been for everyone else as well) and I haven't been able to spend any time in the garage the last couple of weeks. . .

Thanks for your patience and help!

[atomicjoe23]

All I need is the 2 or 3 digits cast into the top of 2 center exhaust ports.

Ron, I'm looking, but there is enough corrosion there that I can't tell what those digits are. . .I'm gonna do some scrubbing with a wire brush to see if I can't get it to a legible point. . .

. . .I just finished removing the hood so I could get a better look.

[Ron Sutton]

Ron, I'm looking, but there is enough corrosion there that I can't tell what those digits are. . .I'm gonna do some scrubbing with a wire brush to see if I can't get it to a legible point. . .

. . .I just finished removing the hood so I could get a better look.

Okie dokie.

[atomicjoe23]

OK, I was finally able to read the casting numbers. . .the passenger side was basically illegible no matter what, but the driver's side was easy to read with just a quick shot of engine de-greaser.

061. . .should be 1967 400 2BBL/4BBL heads with 72cc (or 75cc depending on what site you look at) chambers, press-in studs, and 2.11"/1.77" I/E valves if online sources are correct.

I also finally found the part number on the carb 1850-4 with 3145 below it. . .should be a Holley 4160 600 cfm with vacuum secondaries and a mechanical choke. Should be a good starting point for a relatively stock engine I would think.

[Ron Sutton]

OK, I was finally able to read the casting numbers. . .the passenger side was basically illegible no matter what, but the driver's side was easy to read with just a quick shot of engine de-greaser.

061. . .should be 1967 400 2BBL/4BBL heads with 72cc (or 75cc depending on what site you look at) chambers, press-in studs, and 2.11"/1.77" I/E valves if online sources are correct.

I also finally found the part number on the carb 1850-4 with 3145 below it. . .should be a Holley 4160 600 cfm with vacuum secondaries and a mechanical choke. Should be a good starting point for a relatively stock engine I would think.

Joe, those are the basic D-port headd. If you plan to pull the heads off (or are rebuilding the whole engine) ... I suggest you have a knowledgeable person remove any dimples from the port floor & rework the bowls under both valves ... then do a quality multi-angle valve job where they lap the valve in a final step & install 7/16" screw in rocker studs. This will not hurt any responsiveness nor torque. It will just help these heads build more power from 2500 rpm up to 5500.

The cam I'd recommend is based on your goals & usage. If this is a frequent "driver" ... and/or you want a very mild performance set-up ... I'd recommend this package HERE (http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1215&sb=2)with 1.5 ratio rockers. This will be a good, all around, easy to drive package with power right off idle all the way to 4800-5200 rpm. (Shift at 5000)

If you're looking for a higher level of power ... have a manual trans with at least 3.73 or lower rear gears ... consider this cam package HERE (http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1216&sb=2). The engine will lope, have less vacuum & not be as smooth taking off from idle. It will run stronger from 2000 rpm & up ... to 5500 +/-.

Pick your poison & Best wishes !

[GregWeld]

Good choices!

Cams are so hard to decide on -- we all want the bad ass sound of a big cam - but few of us want the drivability issues they bring.... And frankly NOTHING is worse than a motor that's a dog, torque wise, were we drive "normally". I always liked an engine that pulled with just barely any throttle. That way you FEEL the power without having to have the speed that goes with the big bad boys. To each his own..... some guys love a car that barely runs. Nothing worse than a "lazy" bottom end to me.

Can't tell you how many hot rod buddies that buy a crate motor - low compression - and choose the wrong cam (bigger is ALWAYS BETTER - BS!!) and have an exhaust sound that's just wuss all the way... the cam bleeds off what little compression the motor did make... and the throttle feels like the car is out of gas. HORRIBLE. LOL

[atomicjoe23]

Thanks Ron. . .I'll check those out.

I'll probably go with the milder cam because I don't want a lazy bottom end as Greg-Weld mentioned.

Hoping to have this thing up and running for the first auto-x of the season in March.

Thanks again.

[GregWeld]

Thanks Ron. . .I'll check those out.

I'll probably go with the milder cam because I don't want a lazy bottom end as Greg-Weld mentioned.

Hoping to have this thing up and running for the first auto-x of the season in March.

Thanks again.



I didn't look at either of the cam choices before making my comments about lazy bottom ends.... My comments were more GENERAL about cam choices, and people tendencies to use the "if a little is good - more is better". It's pretty much the way we all think.

[Ron Sutton]

I didn't look at either of the cam choices before making my comments about lazy bottom ends.... My comments were more GENERAL about cam choices, and people tendencies to use the "if a little is good - more is better". It's pretty much the way we all think.

I agree Greg. Most people pick way too large of duration for street cams & the overall power is poor ... especially in the range we drive them on the street ... from idle to 3000. I was always amazed at how many "hot rod guys" would pick a race style cam with a powerband of 3500-7000 rpm .... then drive it on the street 90% of the time below 3500 rpm.

Joe, I was a Pontiac guy as a youngster and these 400" engines make good power from idle to 5000 ... as long as we don't mess it up with cam selection. If was driving the car myself ... often ... on the street. I personally would pick the smaller of the 2 also. The larger one will make the car faster, but the side effect will be the idle to 1800-2000 rpm range will not be as strong, nor as smooth.

With the smaller cam, I think you'll need to keep the compression around 10-1 to avoid detonation. Any higher & you'll probably have detonation issues. Any lower & you'll give up power & efficiency.

If you ever desire to build a more racy Pontiac ... you'll need different heads.

Best wishes.

[atomicjoe23]

Thanks Ron. . .the car will primarily see street & local auto-X (once a month) use for at least the next year so I will probably stick with the smaller cam.

A racier motor may be in the cards, but not until I've improved my driving and the engine starts to hold me back. . .might be a while.

[atomicjoe23]

Ron & Greg. . .this thread has morphed into a cam discussion, but that's fine with me. . .

. . .how would you guys compare this Edelbrock cam ( http://www.edelbrock.com/automotive/mc/camshafts/locator.php?part_number=2157&submit=go ) with the smaller Comp camshaft ( http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1215&sb=2 )???

On paper they are VERY similar, but I don't have enough experience to know how much difference the small differences on paper between the two would make?

I'm looking at exhaust systems right now as well. . .at the moment I'm looking at a Magnaflow system and I have a choice of 2.5" or 3" systems. . .would selecting the 3" exhaust have a negative effect if I have a relatively stock engine (with one of the two cams above; the car already has headers on it. . .I think they are Hooker headers, but I'm not positive because they came already installed on the car and they are wrapped)? I'm just thinking that I would eventually want/need the 3" system when the engine gets modified if it wouldn't adversely affect the engine now.

Thanks again for the help!

[GregWeld]

Just at first glance the Edelbrock cam is rated at 500 RPM higher than the Comp cam -- but otherwise they're pretty similar.

Cams also depend on SO MANY OTHER factors -- head flow etc. A lot of times people get a cam that will flow more air than their heads can handle!! LOL


As far as the exhaust system goes --- A 2 1/2" systems is generally rated to handle LESS than 500 HP.....

A 3" exhaust system is rated at 700HP plus.

The Edelbrock cam says that using their matched parts will create 387HP.... and a Torque number of 439 Ft lbs.... nice and torquey that's for sure.