225 exhaust popping

I have a 71 CJ5 with a HEI distributor. Plug gap set at .045 and 6 degrees before TDC. The jeep runs good but I get a popping sound out of exhaust (headers) when I am cruising and let off the gas. I also have an exhaust leak that I have not been able to pin down. This is not a big problem because I use the Jeep for basicly hunting but like the rest of you I want everything to be perfect. Thanks Lee

 

If it happens when compression slowing then most likely it's the exhaust leak causing it. What happens is when you let off the throttle the throttle plates in the carb close cutting off air. When that happens for a short period of time there is still fuel flowing into the engine, more than needed. The unburned fuel ends up in the exhaust. With an exhaust leak oxygen is introduced to the exhaust system with the unburned fuel, with the heat from the exhaust, and you get ignition. Hence the popping noise. If everything else is set right, carb, timing, choke, etc., then when you fix the exhaust leak the popping should go away. Nickmil

 

Between my jeep and two others with the v6 and headers, we all get a mild pop out the passenger side exhaust at idle. Once your off idle it is not noticeable. It bothers me, but I have simple deduced that it is a natural characteristic of the odd fire v6.

I was getting popping noise upon decelerating, as well. I checked the dwell (this is before I installed an HEI) and adjusted the carb to run just a touch more rich and the problem went away. However, I'm not sure if the repair was a result of the timing or the lean carb mixture.