Bent Pushrod

[Pierre J.]

I removed one of the heads on my '56 today to have one of the plug thread fixed. When I removed the intake, I found that one pushrod on the other side of the engine was bent (exhaust #4). The engine only has about 200 miles on it since rebuild, what caused this pushrod bending problem? The valve and piston appear to be OK.
Thanks for the help,

Pierre G. Joly #34410

[James F.]

Re: Bent Pushrod

Pierre,
I really don't know. However I have a theory regarding a Chevy 6cyl I have that had been shut off and engine sat dormant several years. Eventually, I started it up and shortly thereafter determined that #6 exhaust pushrod was bent. My theory is that the "shock" of the stater turning over the engine (after sitting for years) and possibly the engine immmediately began to run, bent the pushrod. From that point on any engine I leave untouched for several years, I turn over several revolutions by hand before attempting to stard. Do check that the bent pushrod didn't pull the rocker arm stud slightly out of the head. Regards,

[Clem Z.]

the intake manifold bolt

is in line with that pushrod and someone could have put in to long a bolt and bent the pushrod. i have seen that done more than once

[Wayne P.]

Re: the intake manifold bolt

You sure you didn't over rev it? Maybe it was adjusted too tight. Either could cause it to bend.

[Robert W.]

Re: the intake manifold bolt

Had a friend who purchased new GM push rods but the ones he received and installed was slighly longer than stock and bent several after a short test run. Might want to check that since the motor was just redone.

[Joe L.]

Re: the intake manifold bolt

Robert-----

That's a very good possibility. The original pushrod used for 1956 Corvette engines was 7.78" in overall length. Most subsequent Chevrolet small blocks used the same length push rod, too, but that doesn't mean that's what was installed in this engine. The current GM replacement pushrod which meets the original length specs, but is configured differently than the original, is GM #14095256. Many aftermarket push rods of the above-referenced length are also available.

[Doug Flaten]

Re: Bent Pushrod

Last year, I was getting my 65 Lincoln ready to move. I fired it up, and it sounded like a diesel, and had no power. I pulled the valve covers and rockers, and found that 7 of the 8 exhaust push rods had bent. The car had been sitting for a year and rarely used prior to that. I have wondered if it siezed or jumped timing. I know it had not been over-reved

[Clem Z.]

sometimes a valve

will have the stem rust to the valve guide in the open position and if the piston hits the valve it can bend the valve or push rod. that is why i recommend you back off all the valve adjustments so all the valves are closed durring long term storage. i always bump my corvette engines over several time a week durring winter storage to prevent this problem.

[Doug Flaten]

Re: sometimes a valve

Thanks Clem, I was having trouble justifying to myself that all of the valves could have stuck. But I could believe rust as a cause in this engine, because it used to get quite a bit of condensation buildup in the oil.

[roy braatz]

Re: the intake manifold bolt

You may also have your lifters ajusted down to many turns,I ajust mine ONE turn only.

[Joe L.]

Re: the intake manifold bolt

Roy-----

If the engine is as-original and someone adjusted the valves even one turn down, that would definitely cause a problem since all 1956 Corvette engines originally used solid lifters.

[Pierre J.]

Re: the intake manifold bolt

I had a closer look at the bent pushrod and it has a few dent' at the upper end where it goes through the head.. I think the situation described above by Clem's posting is actually what happened, the intake bolt at that location (exhaust #4) did hit the pushrod and caused the problem. These were the correct reproduction bolts and I assumed they were the right length. I have some bolt cutting to do, thanks for the info Clem.

Pierre G. Joly #34410.