The Stovebolt Site Forums The Shop Area Engine Shop 235 engine making a popping noise, help please

I have a 235 in a 55 truck. When the engine is running at idle it will make a popping noise, not a steady popping noise but a pooping noise every few seconds or so. Sounds like the engine is missing a step or something. I figured it may be a valve trying to stick?? The engine sat up for about 6 years or so. I have put a new carb, fuel pump, fuel lines, and cleaned the fuel tank. It also has a new coil, dist cap, rotor button, plugs, and plug wires. It only makes the popping noise at idle and it sounds like it is comming out of the exhaust pipe. When I rev the engine up it does not make the popping noise. What other things can cause this to happen??. Thanks for any help on this.

Might pull the valve cover and look for a bent push rod. Could be a valve stuck, bending the push rod.

great thanks for the help. I was also thinking that the timing may be a little off so I will check that out today.

wasn't the timming, I will go ahead and pull the valvr cover and check it out

if you have a vacuum gage plug it into the wiper connection on the intake and start the engine. post your findings.

This is what a bent push rod sounds like.

....video.click...

The noise continues upon acceleration, not just at idel.

after replacing bent push rod
...video.click...
Good Luck

Mine did this same thing for the longest time. I replaced the intake and exhaust manifold gaskets and new exhaust (Old was rusted out). it helped a lot. But what helped the most was running 89 to 91 octain. The 87 was making it pop like crazy at idle. But if I gave it any gas the popping was gone. Try this and see if it helps. I rebuilt the carb, new fuel tank and pump, set the valves a 1000 times and this was all that really helped.

A compression test is probably in order. I would think that would show a burnt valve. Is it possible an exhaust valve is simply set too tight?

Thanks to everyone for all the help. I think I have figured out the problem. The wire that goes into the distribitor is loose on the inside and shorting out at the points. I had the cap off yesterday and I had forgotten to remove the battery cable. I was checking the connections to the coil and noticed that the wire in the distribitor was arcing when I shook the wire. I had changed everything out but one thing, the points. So I put the cap back on cranked the truck up and fiddled with the wire and the popping went away. But I'am sure it will act up again so I'am going to put one of those Pertronix electronic igintions in it. I ordered one the other day. The part number was 1168 for 54 to 62 6 cylinder trucks. I have heard some really good things about them so hopefully I will get the points problem took care of. Other then that the engine runs real good, cranks up no problem. And thank you very much Dad550 for the videos on how a bent push rod sounds. That really helped a bunch to rule out a bent push rod. The popping sounds more like the engine is out of time a little. But it does not back fire through the carb. There is no rythum to the pop noise. The engine will run and make a sporatic light pop noise through the exhaust. And thank you 51 Ashton for the tip. But I have already plugged the vaccum at the exhaust manifold. I changed over to electric wipers instaed of the vaccum ones.