C2 Engine popping noise

[Randy S.]

Gentlemen,

Re 66 327 300HP 4 speed

I recently had my distributor rebuilt and reinstalled it myself. Finally got to take it out yesterday and had a popping noise in the exhaust. Had to gently squeeze the gas to minimize the issue. maybe 30-40 pops in a 5 mile ride

When I picked up the distributor the rebuilder demonstrated the centrifugal advance in the Sun machine. I am only getting 27* instead of the specified 30*. He said not a major concern.

So I figured I did not get the wires in the correct firing order so I rechecked that today. They are correct. Base timing is 8* ( spec is 6* thought I'd make up for the "short" centrifugal advance)

Took another test drive today w/o the ignition shield installed and no issues. Runs great. Could the coil wires be shorting against the edge of the shield?

My shield has the plastic liner under the top and I have also put a few layers of duct tape in the area where the coil terminals are.

Car has been sitting during the winter months so could be bad gas too. Should in insulate the inside of the shield to prevent any misfires?

Randy

[William C.]

Re: C2 Engine popping noise

Yes, the coil wires could be shorting to the shield. It's very easy for this to happen. I always check the wires when reinstalling the shield, because it happen once to me. The plug wires could be your problem also.

[Timothy B.]

Re: C2 Engine popping noise

Randy,

Take the duct tape off as that may be your problem and drive the car again, I think the duct tape will conduct electricity.

[Donald O.]

Re: C2 Engine popping noise

Randy,
Make sure all of the plug wires are fully seated in the cap. You might have a case where a wire is being held out just enough by the end boot at the cap.

DonO

[Larry H.]

Re: C2 Engine popping noise

It is possible the distributor was rebuilt and not properly phased. GM had a specific method in building the distributor....and this issue is common as many shops do not rebuild the distributors properly phased....Have the distributor checked on a distributor machine.......by a professional.

[Donald O.]

Re: C2 Engine popping noise

It is possible the distributor was rebuilt and not properly phased. GM had a specific method in building the distributor....and this issue is common as many shops do not rebuild the distributors properly phased....Have the distributor checked on a distributor machine.......by a professional.

Please explain this "incorrectly phased" distributor.
DonO

[William C.]

Re: C2 Engine popping noise

I'd start by eliminating the obvious, take the top shield off, and reseat all the wires firmly in the cap. leave the shielding off and go for a ride. try to make it pop. If no pop replace the dist cover and try again, if popping (with just the shield properly in place) then you have narrowed the problem down to a wire shorting to the cover. Replace wires, problem fixed. Otherwise you have to dig deeper, for a problem that may not be electrical. Is timing correct? )Only "phasing" I'm aware of on a Chevy distributor is to have the rotor tip on the top aligned with the dimple on the bottom gear. (I've only worked on a few hundred over the years) Recheck timing.

[Randy S.]

Re: C2 Engine popping noise

Thanks guys for all the suggestions

Verified all the plug wires were in their sockets. Added a piece of rubber hose along the bottom back of the ignition shield to prevent the two pink coil wires from rubbing against the shield (saw no evidence)

Installed ignition shield and test drove with no popping noises.

Ignition, bad gas, carbureation who knows but no issues today.

Randy