2 Bent Pushrods in 350 SBC

[Decline]

1969 camaro with non orignal 350 SBC with iron heads a mild edlebrock flat tappet cam, crane stamped roller rockers and mystery valves, springs, push rods all done by previous owner..But it does have all ARP hardware so thats a plus

I heard some clacking under the hood. Car had been idling funny yesterday afternoon. I thought maybe my recently changed timing was causing pinging?
Pop'd the hood..Distinct metal chatter from valve cover..Opend to find the rearmost rockers all twisted. Further inspection revealed 2 bent push rods.

Question, what else should I inspect for damage? One of the valve ends is messed up a little/flattened and put some wear marks on the roller tip. I would have to remove the head to change it obviously? Can i get away with just replacing the 2 push rods and reseting the valve lash to get back up and running?

I feel like that should be fine for now until I decide wither to change the heads out for aluminum or just swap an LH6 5.3 aluminum truck motor in there. Ive had my eye on one on craiglist for $750 with no accesories. Prbly run it carbed innitially for $ reasons

[Sieg]

First thing you need is compression, as in no bent valves.

I'd want to know why it happened before going any further.

[Decline]

I can do a compression test on it to see if the valve is damaged on more than just the top..
My assumption is that rockers were loose and got out of alignment with the pushrods.
Does anyone else have any theories on what causes this?
Another friend of mine recomended taking a look at the lifters as well to see if there s damage..
I really wanted to avoid taking the engine apart

[GregWeld]

You may be able to get away with a "lash cap" on the messed up valve. But then this push rod length would need to be adjusted due to the now "longer" valve stem.


Now then. - this didn't just bend like that as you were casually driving down the road. My guess is you experience a severe backfire or you were getting after it pretty good.

My question would be: what was the timing? Why did you decide to adjust it? And what did you adjust it to? And did you adjust and or check the TOTAL timing?? And what was that number?

[Decline]

You may be able to get away with a "lash cap" on the messed up valve. But then this push rod length would need to be adjusted due to the now "longer" valve stem.

Never heard of a lash cap..i will look into it. This could be a possible band aid along with an adjustable pushrood[/COLOR]

Now then. - this didn't just bend like that as you were casually driving down the road. My guess is you experience a severe backfire or you were getting after it pretty good.

It happened as i was leaving work. I went a few blocks and heard the rattleing/clanking, so i turned around and came back. I thought it was just mis firing. A couple hours prior to that my buddy and I were in the parking lot attempting to check the timing again cuz the car seemed to be running rich and smoking covering my rear bumper with a thin film of black soot. The idle wouldn't settle down enough to check base timing..I rev'd it a few times at the carburator to try and get it settle. I heard some pings or pops during that time also.

My question would be: what was the timing? Why did you decide to adjust it? And what did you adjust it to? And did you adjust and or check the TOTAL timing?? And what was that number?


My engine has never really run right since after I got my suspension installed a few months ago. I've tried various fixes.
It is an AME front clip so the motor had to come out.
My old headers were "massaged" to fit which meant the shop beat one the tubes about 2/3rds closed..So I got the AME headers to clear control arms. That seemed to work for a while..
Performance was still spotty so I got new plugs and wires.. Was better.
Then it occured to me to check the timing..Well the distributor was loose so i thought id found my culprit.. I bought a timing gun watched a few youtube videos and set my initial timing to 12degrees, then i set my total timing to 36 degrees-ish.. I say "ish" because I had no tach to reference engine rpm so i manually rev'd it to what i figured was between 2500-3000..
It was actually running pretty good like that and i did the Del Mar good guys autoX a few weeks ago. Other than my high idle and crap gas mileage(10-12 down from 15-18) I thought i was in decent shape, just thought the carb needed tuning..

[Che70velle]

Solid or hydraulic cam? Do you know how to check and set valve lash?

[GregWeld]

An adjustable push rod is a checking/measuring tool.... there is no such thing that you could use to actually run the motor with.

At this point there is only ONE correct way to fix/diagnose your issue.

Drain your coolant
Pull the distributor
Remove the intake
Remove the head and fix the valve

There's something going on here that needs to be solved. My guess is you have a cam going flat.. which you'd be able to see if you remove the intake manifold. That would explain your running rough and inability to keep the car in a steady state of tune. The cam "going away" would allow the lash to open - pounding the pushrod - and stressing the valve train.

[Vince@Meanstreets]

Im with these guys, there's more than just push rods doing on. With possible mis matched stuff going on the best bet would be to replace the two bent push rods. Check ratio, check for coil bind and make sure your retainer isn't hitting the valve guide.

Did you over rev the engine recently?
Are you using coolant? Hydraulic that cylinder?

7&8 are the most common to go flat. Especially if you had just replaced an intake manifold and or gasket.

[TheJDMan]

The first thing I would do is run a compression test. You may need to borrow push rods from a neighboring cylinder to test #8. A push rod does not bend like that unless there is an underlying problem. As has been stated there is only one correct way to fix this and that will involve pulling the heads and doing some investigating. I would be looking at things like valve spring coil bind or rocker arm clearance issues and depending on the cam look at valve to piston clearance. Those heads don't appear to have guide plates which would help stabilize the valve train. You never stated if that engine is equipped with solid or hydraulic lifters. Let us know what you find.

[Decline]

I prbly should have tested the compression before I tore it apart. I was expecting to see piston to valve contact. There was none. How can I inspect the cam? Pull it out or just remove the #8 lifters?
The rest of the push rods on the even bank seemed straight by the roll method. The rockers on the other bank seemed pretty loose. Those push rods also seemed straight.
I would to get this engine back up and running while I decide on the future. Could it be as easy as 2 push rods and a valve and maybe a new flat tappet cam?
Also I need to figure out a better way to post pics. Should read that sticky about it posted somewhere.

[GregWeld]

I prbly should have tested the compression before I tore it apart. I was expecting to see piston to valve contact. There was none. How can I inspect the cam? Pull it out or just remove the #8 lifters?
The rest of the push rods on the even bank seemed straight by the roll method. The rockers on the other bank seemed pretty loose. Those push rods also seemed straight.
I would to get this engine back up and running while I decide on the future. Could it be as easy as 2 push rods and a valve and maybe a new flat tappet cam?
Also I need to figure out a better way to post pics. Should read that sticky about it posted somewhere.



You should be able to see the cam thru the valley in the center of the block - looking down from where you removed the intake.... There's plenty of room to just look straight down there... and yes - pull the lifters out -- but keep them so that you know exactly which lifter bore they came out of. If they're okay -- and the cam is okay - then they need to go back to the bore to which they came. DO NOT mix them up. What you want to do is to feel how the lifters came out -- they should come out with zero effort - and be smooth... and not "sticky".

You can rotate the motor by using the crank bolt (after pulling ALL the spark plugs).... at the crank pulley (the lowest one). You can put a socket on it and a half inch ratchet or breaker bar and slowly rotate it. As you do this - look at the lobes on the cam. There should be NOTHING on the cam lobe that looks weird or ugly or scored or anything other than wonderful.
Make sure all the plugs are pulled -- and the car is in neutral.... if it doesn't rotate pretty easily theres something not right -- you're in gear -- or all the plugs aren't out - or?? There's no compression with the plugs pulled... What I'm trying to say - is don't force it if it doesn't rotate fairly easily. You don't want to break off the crank bolt!

[GregWeld]

I don't see any guide plates on this motor --- and that might have been the issue -- when you started to run the auto cross etc - you're revving the motor... and maybe the rocker started to wobble -- and the pushrod got caught up in the whole mess and bent - starting the motor to run rough.... and then spiraled from there.

I've never run a SBC without guide plates!

[Decline]

It's possible I may have over rev'd it at Del Mar. I put the TH350 in 1 and ran the course without shifting.
The lifters are solid. I will attempt to pull them out tomorrow. I need to check the springs for binding or a stuck valve. I'm also going to drain the oil to check for metal and try to rotate the crank and see if it moves freely.
I might as well pull the other head off now too..seems like good practice:hairpullout:

[GregWeld]

Welcome to hot rodding..... LOL

[Vince@Meanstreets]

It's possible I may have over rev'd it at Del Mar. I put the TH350 in 1 and ran the course without shifting.
The lifters are solid. I will attempt to pull them out tomorrow. I need to check the springs for binding or a stuck valve. I'm also going to drain the oil to check for metal and try to rotate the crank and see if it moves freely.
I might as well pull the other head off now too..seems like good practice:hairpullout:

them oil deflector springs don't like high RPM. I agree on the guide plates.

[Che70velle]

Agreed. Guide plates are necessary for high rpm's. If your going to keep what you have here, meaning the small block chevy, I'd invest in a set, and have a quality minded machine shop set the heads up for them. As Vince stated, lose the cups on the springs...they are heavy.
You stated that the rockers were loose on the opposite bank. You also stated that this is a solid camshaft, and not a hydraulic. That tells me that you have an issue, as the rockers should not seem loose, unless you are referring to side to side movement from the lack of guide plates. A solid cam will hold its end play, so you shouldn't see any noticeable movement at the rocker. .010 to .012 is an average number for rocker to valve clearance, which moves very little with your hands. The rockers that you have are self aligning, and aren't a bad piece, you simply need your valve train to operate as a complete package, and a set of guide plates will compliment the valve train.
If your happy with your camshaft, and it isn't hurt, have your machinist set up your heads correctly. They will set the spring heights up according to your camshaft specs, and help you make sure that when this all goes back together, it will be correct. If you end up with a new camshaft, have them set up your heads to the new cam's specs. Pushrod length, spring installed height, rocker to retainer clearance, coil bind at full lift, are all important issues with a performance oriented valve train, so pick your machinist wisely. Triple check your settings after your all back together, and pull your valve covers every now and then, to go back through them with a feeler gauge to find problems early, before this happens twice. Solid lifter camshafts are fun, but are high maintenance.

[Decline]

More investigation of the crime scene commenced this evening.. I removed my crappy old leaky water pump to gain easier access to the crank bolt. The only accesories left connected to the block right now are the power steering and the starter. I attempted to rotate the bottom end and it spun fairly easily. I applied some shell rotella i had laying around to the cylinder walls and faces of the pistons and mating surface of the block so it wasnt dry. Then i pulled the #8 lifters out with a magnet. They slide out pretty smoothly(and dropped back in well also) All the lifters cycled smoothly as well. The one area of concern is I think the #8 exhaust lobe had like a small nick on it? Might have been oil but I tried to get a couple good pics of it. I dunno. Its a mystery.

My uncle thought it was weird that both push rods go in one cylinder at the same time. He thought the wrist pins let go. I only spoke with him on the phone and he hasnt seen the engine. I feel like the bottom end is fine
Other theories are that I floated a valve and screwed up the valve train but it took a couple weeks/drives for it to manifest itself in the bent PRs

Option 1..My friend at work knows a cylinder head shop that does good work but I'm torn spending like $2-400 fixing 1 old iron head. I need to call for an official estimate. This would be the fastest cheapest option. Maybe add another $150 for a new flat tappet cam that matches the existing springs

Option 2. I'm also conflicted on spending money on aluminum heads and guide plates and roller rockers and push rods ands a new cam. My engine leaks from the front and the rear and maybe the trans also? Not alot of fluid but enough to make a mess of my fancy suspension and annoy me in general
I guess $1500 isnt terrible to be back up and running and with like 75 more hp..

option 3
Get another engine. Definitly the long road and most exspensive. The LH6 i found on craigslist sold..Dammit. I would of had to refresh it anyway but the long block sold for $750. An aluminum 5.3 with 243(LS6)heads would have been sweet.. The GMPP carb intake manifold and MSD LS controller are about another $700. I need a flex plate to adapt the trans to an LS. Headers that work with an Art morrison front sub $800ish, the AME engine mounts. Anything else Im missing?

Ive got some decisons to make. In the mean time I put the passenger side head back on with 2 bolts and put the valve covers and manifold back on to kind of seal the motor up.

[Decline]

More pics

[Decline]

Also, thanks to everyone who posted for trying to help me figure this out and specifically Mr. Weld who came up with a plan of action for me to follow. I'm a newb when it comes to the actually turning of wrenches and your step by step instructions helped immensely. I'm not out of the woods yet but atleast I now have some information to go on.:thumbsup:

[GregWeld]

So first of all --- you're doing fine. All of us on this forum have walked in your shoes... And EVERYONE starts somewhere.

Okay -- I several things I don't like - and you won't like what I don't like. The motor has been scraped in the valley.... with a scraper. That tells me that someone has been in there and did a "quickie" clean up and if they had to use a scraper to clean up in the valley -- that tells me there was heavy sludge build up. That's never a good sign of health. That's the sign of a motor with milage and poor maintenance, i.e. oil change were few and far between.

The other thing I'm seeing is heavy carbon on the piston tops... which is an indication that it's been running "rich" and there's probably also some oil usage...

At this point --- If it was me --- I'd be shopping for a fresh "long block" - i.e., block with heads. Here's an example.


This is a quick way to get back up and running with some peace of mind that the bottom end etc is healthy... you drop it in and bolt on your accessories... tune it and enjoy. Just a thought. This example would probably just about double your power.

http://www.summitracing.com/parts/mll-bp38313ct1

[Decline]

Quick update. I got my head back from a shop with 1 new valve. He said the rest looked decent. It was super cheap and supports my "just get up and running" mentality. I was shopping for a new cam and lifters and pushrods for peice of mind and I stumbled across top end kits on summit.
Looking at this right now
http://m.summitracing.com/parts/tfs-k314-445-405
It's a bit more then the $300 I would spend on the peice of mind cam/lifter/pushrod kit I priced out but if it delivers the 450 claimed hp then I'd prbly be happy with this setup for a while.
The aluminum truck LS on CL was snapped up and the extra expense/headache of converting has me shying away in favor of just keeping my current setup +more power
I have modest goals of 450ish hp for street/track work and am getting antsy since the car has been down almost a month
I'm all over the map!

[SSLance]

I've always been told to not make major changes (upgrades) to the top end of an engine without being positive of the condition of the bottom end first. In your case it seems like the questionable parts might be the rings and bearings which you won't know without pulling the long block apart.

If I was on a budget just to get it back together and running again, I'd lean towards just a new cam\lifter setup that will work happily with your heads and compression ratio and call it good. I wouldn't make any major performance enhancing upgrades without going through the rest of the engine first.

The pulling and disassembly of the engine isn't much more work than you have already done and if it is all good inside, you might be able to get away with just replacing the bearings. This would also give you the chance to fix all of the leaks properly.

[Decline]

Good point..I tend to get carried away and go flying off the high board when it comes parts. More is always better right?:headspin:

I should stick to my plan for now. The engine will have to come out when I eventually ditch the TH350 for a T56 and I can worry about rebuilding it then.

Here are the 3 cams I was looking at from summit in order of mild to spicey

http://www.summitracing.com/parts/sum-k1102/overview/make/chevrolet
Duration 278/288, Lift .421/.444

http://www.summitracing.com/parts/sum-k1103/overview/make/chevrolet
Duration 288/298, Lift .444/.466

http://www.summitracing.com/parts/sum-k1105/overview/make/chevrolet
Duration 298/304, Lift .466/.487

Again, I should prbly play it safe with the 1102 but here is a supporting article in Hot Rod from 1999 where the 1103 and 1105 where dyno'd on a 350 with freshened up stock heads. If you click the pictures theres alot more info..The 1105 only produces 12.7 vaccum in the test which is a little low for my power brakes so I'm thinking the 1103 might be a good middle road
http://www.hotrod.com/how-to/engine/camshafts/