The Stovebolt Site Forums The Shop Area Engine Shop High idle + exhaust popping

I could use some help troubleshooting:

Just brought home a '64 c10 on Friday night. It is idling at about 2,000 rpm and there is a popping sound that is most notable at the exhaust pipes. The popping sound isn't all that regular (as in every 1 second). Usually the popping starts after it has been idling for a minute or two.

The engine has a Edlebrock 1406 Performer Carb, 600 cfm, four barrel. Its been raining here since I bought the truck, so I know it is a small block chevy V8, but can't get in there to find the block number to be totally sure whether it is a 350 or 327.

There have been two or three times when the planets have aligned and the engine hits that sweet spot of 800 - 900 rpms and stays there for a bit ... no popping sound then.

I'll admit to being totally green here. I've downloaded the carb manual and have done on-line research. Here's my list of top contenders:

Vacuum leak; choke needs adjusting; timing belt needs adjusting; spark plugs; ignition cables. There are other options here I've read about that sound a lot more serious.

I'll bring the truck to a shop if I have to (when I can get the $$), but would really appreciate any thoughts on how to approach this and what it might be.

First start and check if the choke is not adjusted properly. Is the carb idle screw set too high? Then look for vacuum leaks. Whatever you do, don't start replacing parts. Sounds like something is out of adjustment to idle that high.

Choke, including all linkages; idle speed and mixture adjustments; ignition timing and distributor condition, including advance mechanisms; vacuum leak(s); cap, plugs and wires are easy and cheap. There is no timing belt.

cm

First check to see if the choke is going off. With the air cleaner off start the engine. If it has an electric choke use a test light to see if you have curent to the wire on the choke & the ground wire is hooked up. The butterfly on the choke should gradually open as the engine warms up till it is straight up & down. You need to familiarize yourself with the adjustments on this carb. They are basicaly simple. There is an adjustment on the drivers side fro the idle speed & one on the pass. side for the fast idle when the choke is on.

I had a problem with my 1406 until I realised that the linkage return spring ( mounted to the rear of carb.)was holding the choke linkage from dropping down after warm up. Thus I could not idle down with the fast idle screw. Just my 2 cents.
Al

Thanks for the pointers ... very, very helpful. With this info and a knowledgeable buddy coming by to drool over the truck and work with me, hopefully we'll get this figured out.

This website is pretty awesome. Good community of people here.

Having the same issue's today trying to break in my 57 235. Looking at swapping the 12V coil out with another one just for process of elimintaion.So far changed out new point's/plugs/condensor/wires & all on a dual Fenton intake with BC carbs. If that doesn't work looking at removing duals and installing single carb just to break motor in.

Good luck!

A very lean condition will cause the above problem...!!???

Dual carb setup will idle higher.

Got it fixed. The electric choke wasn't wired up properly. With that, and a little adjusting, the idle is perfect.

However, there is still the occasional popping sound from the exhaust. I'm thinking that is caused by the fact that the exhaust pipes are pretty short ... they only come out to a bit past the rear of the cab, with the muffler sitting directly under the cab. I'm considering having them extended, but will need to figure out just how much farther.

Thanks to everyone that posted and I hope this helps others.