Way smoother but......

Well just finished the HEI upgrade on the ol' girl and she does run a lot better but I still have some back fire issues. When I back off on the throttle quickly she sometimes starts to Pop,pop,pop and just every now and then when she is warm and I let off she will give out a small back fire. Is my mixture to lean?rich?

 

Popping in the exhaust means there's unburnt fuel in the exhaust... too rich, though the mixture will go rich momentarily if you close the throttle suddenly. What do your spark plugs look like?

There was a thread about dashpots a couple weeks ago that discussed this. If your carburetor has no dashpot, that would contribute to the popping.

 

I am missing the rod that comes out of the diaphram of the dashpot. Can a person still get that part? The dashpot I mean.

 

Maybe. Standard shows a D5-35F but lists it as a Holley app. for a 2V 6 cylinder... http://www.smpcorp.com/wmimages.asp?file=D535F.jpg&partnum=D5-35F

 

I had the same problem, it turned out the coil was bad. One new coil later and the problem is gone. You might want to check this if your mixture is OK.