Hot engine troubles

[Second Series]

This is a ‘47 Chevy 2nd series with a ’54 235, SM420, and 3.73 diff. I have a few issues to work out. It is hard to start after it has run awhile. If I drive somewhere and shut it off. If I don’t touch the gas pedal, I can tap the floor starter and it starts right up, but if I even look at the gas pedal it won’t start. I had the carb rebuilt awhile back, but that didn’t affect the hot start issue. I have been reading about similar problems, and realized that I may not have the Ballast resistor bypass so I’ll try that unless anyone has any ideas what else I could check.
If I drive around awhile and stop/start it a few times the engine sounds like a popcorn popper. The engine was originally solid lifters, but it now has hydraulic lifters/camshaft. This is the second engine I’ve had installed and the camshaft and hydraulic lifters came from the first engine. When the first engine was running, I abused the lifters by not adjusting the rocker arms after replacing the head. I replaced a couple bent pushrods and some lifters in engine number one. (That engine was done when a valve broke off.) I found a replacement engine and the mechanic found a crack in the cam gear, so he took the camshaft and lifters from my first engine. He mentioned that some of the lifters looked partially collapsed, but since he was out in the boonies and didn’t want to drive to town for new lifters. The engine ran fine for a while, just rattled a bit. After a few years, I had a mechanic adjust the rockers and it sounded better, but the popping when hot started. He suggested a bent distributor shaft, so I replaced it with no change. My suspicion is that there is a collapsed lifter that when the oil gets hot, that lifter expands causing a valve to not seat and I get to hear that cylinder firing. The only way I’ll know is if I pull out the lifters and check. What else do you think could cause this popping when hot issue?

[Valarius_Starchaser]

I once had a similar sound in a 454 that I had come with a 65 impala I bought guy swore it was a fresh cam install but I heard a "popping" sound when it got warmed up then I broke down and found a pushrod or two loose and 4 rounded cam lobes and atleast half a dozen mushroomed lifters.

Not sure how reputable the guy is that put that first engine cam in is but if it was me I would have at the time got all new lifters

1. take of the cover and see if any push rods are loose
2. If they are check valve lash to see if they simply needed adjusted
3. Try and remove the suspect lifters if the problem continues if they are mushroomed no way to get them out from the top very easily

Best of Luck

[Coupeguy2001]

It sounds to me like your valves just need adjusting.
Sort of sounds like they might have slowly gotten tighter over time if the adjusting nuts weren't tight..
the popping through the carb sounds like an intake valve hanging open, and when the cylinder fires, it blows back through the partially open valve, and blows up through the carb.

It has been my experience that you cannot use lifters in a different engine due to the manufacturing tolerances when the engines were machined.
Especially engines that old where everything was set up by hand, with no computers or robots doing the work.
My advice to you is find out if you have a flat lobe on the cam, You might be able to get an inexpensive depth micrometer(dial Indicator) from harbor freight.
then do a compression check.
For the lobe check,
1. take the coil wire out of the distributor,
2. then take the rocker cover off,
3. use magnets and some cheap angle iron screwed to the rocker cover hold down holes. make it like an erector set kinda
4. set up a depth micrometer over the individual rockers and find out how far they move by slowly hand cranking the engine with a socket on the crank hub on the front.
5. do all the intakes, then do all the exhaust.

I don't know what your cam spec's are, so just go by rule of thumb. All intakes move the same amount, and all exhaust will move the same amount.

6. after you determine that you determine that the cam and lifter elationship is ok, then do a compression check.
1. take all the plug wires off, and use masking tape to number the wires, front is 1, last is 6.
2. then unscrew all the spark plugs.
Check them, and make sure they all look the same.
The ones that have a lot of carbon on them, or smell like gas are your suspect cylinders.
Any that are super clean indicate that you might have a bad head gasket, or cracked head, letting in some water, cleaning the cylinder as it fires.
3. scrrew in the compression tester to the first cylinder, and crank the engine 3 revolutions.
4. do the same for all the cylinders.
5. write down on a piece of paper what the compression is.
If they are all within 5 PSI, you have a healthy engine.
If they are off by 15, you may have a leaking valve.
IF the rockers are screwed down too tight, you can get a leak that way.

Ok, if all seems ok, then you have to start looking for other things.
Do all this and get back to us.
I have checked lifters on 6's with a feeler gauge, and set them at .030 as a baseline.
thirty thousandths isn't too tight and not too loose for a test.
After all of this, put the spark plugs back into the engine, and hook up all the wires.
try starting it, and see what you get if all seems fine.

[Second Series]

Hey thanks, I'll try to find some time this winter to tear into it. I don't drive this much anymore, but I'd like to. I'll post when I get to it.