VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 Running rough

Hello all, I just got my engine back together after rebuild & am having issue getting it to run smooth; I have set the timing but no matter where I set it, it is not correct. Using a vaccum gauge it will not run in the green margin ( 18 to 20 pds; I believe I somehow mixed up the lifters & pushrods; could this be the problem & if so will it eventually break itself in? Thx for your advise. Oldgzr

What is the compression reading on each cylinder? If you don't have a gauge, does you thumb get pushed off the spark plug hole when you turn the engine over? All with the same result? Have to push hard with your thumb to overcome 30-70 psig.

Are the valves adjusted properly. Mixing of the push rods and other valve train parts makes little difference as the final valve adjustment is what counts.
Timing has little effect on in a smooth idle. Vacuum leaks and valve adjustment a large effect.

Thx chevgene for your reply; I have adjusted the valves a couple of times (1/2 turn down ) also I sprayed brake cleaner on intake ports & aroung carburator with no result; It does seem like vaccum leak but haven’t been able to locate it at this point.

1/2 turn down?

What model engine is this?

I assume it is a 1933-1936 .

No, I neglected to say it is a 1958- 235 cu

The truck is a 1936; It has headers on it & the original intake.

If the engine is a 1958 and from a passenger car it will or would of had hydraulic lifters. They are adjusted 1 1/2 turns down from where they just stop clicking while adjusting with the engine running. Try backing off all adjustment to where they all click slightly and see if the idle is still rough. If it is the problem is not in the valve train.
Was a new camshaft installed?

When asking questions you have to be as specific as possible so that we will understand your question totally and that you will get the correct answer. Without mentioning that your engine is actually a 1958 replacement then we assumed that the engine in your 1936 vehicle is a 1936 engine, therefore, the answers posted will be based on that assumption.

No, It’s the same camshaft that was in the engine before the rebuild.

Sorry, I’m old & missing some brain cells.
😄

Ya, if you are in the old car hobby then you have to be missing some brain cells. I have that same problem as well.

All the cylinders are 153-155 compression.

Is the 235 engine from a car or truck?
If from a truck solid lifters must be used with the truck engine. If hydraulic lifters are used the idle will be very rough.
Another problem is an intake manifold to head vacuum leak due to mispositioned pilot rings for the intake ports.