Backfire

[taffrail]

I have a small pop between shifts after it warms up, what should I check first, fuel or ignition.

 

[jm29henry]

Both probably running rich,but if timing is off or week spark both could cause your problem

 

[Mitch//pa]

Assuming your timing and points are both set to specs, usually running lean or retarded timing causes the little pops ,,,,,open the GAV a little more ... You can also try advancing the timing a little more...
An exhaust leak can also make pops on decel

 

[steve s]

I will break the tie and vote for running too lean.

 

[larrys40]

Assuming your timing and points are both set to specs, usually running lean or retarded timing causes the little pops ,,,,,open the GAV a little more ... You can also try advancing the timing a little more...
An exhaust leak can also make pops on decel

I agree with Mitch.. Look for all he prescribed and cracks around the exhaust and/or intake manifold as well.
One of them will solve your issue.
Larry

 

[taffrail]

The GAV and the spark didn't cure it, been getting louder , thought my hearing was coming back, I better check for leaks.
Thanks for your help guys, I'll let you know.

 

[larrys40]

I worked on a roadster recently that was doing the same thing and I had just serviced it and in looking at it the exhaust manifold was cracked underneath the intake . I believe the owner ran it and forgot to advance the spark and probably got it hot which might have promoted the crack quicker . It's in my winter service list and know that will cure the problem.
Check it all out and look for manifold issues, leaks, etc
Keep us posted
Larry Shepard