The Stovebolt Site Forums The Shop Area Engine Shop 1955 235

Hello everyone, haven't been on here in a while. My bad. Got a question for everyone. My 235 c.i.d. has an idle problem. It misses at idle. I can remove the #5&6 plug wires at idle and it won't change the r.p.m.'s of the engine. I can raise the r.p.m.'s and it doesn't miss. Of course the plug wires are back on. Can't figure this on out. As usual any help will be appreciated.

Possible worn distributor parts.

You probably have a vacuum leak at the intake gasket on the5-6 ports.

The dist. is fairly new, doesn't mean it isn't worn but I have not thought about a leak on the intake gasket. See, as always this site is the best. Thank you so much Woodswarrior and Wrenchbender RET. Now I'll check both and see if it helps. By the way, once the engine gets some RPM's on it it runs great. Just thought I'd throw that in. Again, thank you very much. Steven

What you describe is classic for a vacuum leak. Don't forget to also check the vacuum wiper motor and hose.
Carl

Didn't get to check it yesterday, had to "mow de lawn." That's French for cut the grass. Believe me we have a lot of grass. Just about an all day affair! I'm going to go over all the vacuum connections hopefully today. Thanks for the input.

Made a vacuum check today using W-D40. Didn't find any leaks. I think W-D40 will make the engine rpm raise if it is a leak. Right? / Wrong?

Squirting any liquid around a suspected leak should make the engine operate "differently" if there is a leak. A combustible material (propane for example) will increase the speed if there is a leak. An oil may smooth out the engine, but not increase the speed if there is a leak. Kinda' depends on whether the engine is already rich or lean.

I mentioned the distributor issue because I ran into it with a 4 cylinder engine with a worn cap and rotor. It would not idle properly, but smoothed right out when speed picked up. In fact it smoothed out when you pushed the distributor cap sideways. May have even had a slightly worn distributor, but the new cap and rotor fixed it.

UNLIT propane torch is the ticket for finding vacuum leaks.

Could also be a badly worn cam gear/cam gear retaining plate. This happened to me about 35 years ago. It will cause the cam (at idle only) to wander in and out. Sounds odd, I know, but it will happen and when it does it changes your timing enough to make the engine miss and idle roughly. This disappears at rpm higher than about 7 or 800. The frustrating thing is there is no easy way to fix this and you can check about 10 things before you finally find it. Good luck.
Jon

Thanks a lot guys. I've got some things to think about now. The bad part or maybe the good part is the engine runs great after it is above idle. Oh well, I've got work to do now. Again, thank you so much. Steven