2 Bent Pushrods in 350 SBC

[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]

Originally Posted by 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.

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