Backfiring.

[TJ's Chevy]

Another reason the HEI helps with that issue. More spark at the lower RPM. You can pick HEI's up for the 6 cylinders real cheap.

[hevymetl]

I forgot to add it already has HEI. Rather, Im assuming it has HEI since it has newer distributor and no points or condenser. I can live with it. Its not ridiculous loud like shots going off, just a rumble or popping with the back pressure like was mentioned. I dont think its worn valves since the motor has recently been rebuilt. I really just need to fix this exhaust leak. Its right at the first joint after the manifold. Its a 2 bolt clamp, which Im assuming has a ball and socket type connection. Im hoping I can find something that I can do a bolt on replacment fix with rather than taking it all down to weld. Does anyone know if I can just order the whole shebang? Its pretty rusted so a total replcement wouldnt be out of line. Thanks for all the replies on this, Im lovin cruisin this truck around. I went to the lumber yard the other day to pick up railings for my deck, and like 3 different dudes commented on my "work" truck.

[TJ's Chevy]

Originally Posted by hevymetl

I forgot to add it already has HEI. Rather, Im assuming it has HEI since it has newer distributor and no points or condenser. I can live with it. Its not ridiculous loud like shots going off, just a rumble or popping with the back pressure like was mentioned. I dont think its worn valves since the motor has recently been rebuilt. I really just need to fix this exhaust leak. Its right at the first joint after the manifold. Its a 2 bolt clamp, which Im assuming has a ball and socket type connection. Im hoping I can find something that I can do a bolt on replacment fix with rather than taking it all down to weld. Does anyone know if I can just order the whole shebang? Its pretty rusted so a total replcement wouldnt be out of line. Thanks for all the replies on this, Im lovin cruisin this truck around. I went to the lumber yard the other day to pick up railings for my deck, and like 3 different dudes commented on my "work" truck.

I believe exhaust leaks can also cause back firing as it allows cold air in.

[Captmatt]

My truck also backfired on deceleration. Turned out to be a exhaust manifold leak. Good quality gasket with spray on copper coating was the fix. Also check the manifold for cracks...... Good luck

[hevymetl]

Can anyone steer me in the right direction as to where I can purchase the pipe and clamp set up directly coming off the manifold? Ive been searching but everything I seem to find are ss high perf systems, or headers, or for only v8s. No one seems to have stock type replacement stuff for a 250ci 6cyl.

[jdl71]

Originally Posted by TJ's Chevy

Another reason the HEI helps with that issue. More spark at the lower RPM. You can pick HEI's up for the 6 cylinders real cheap.

Sorry for the hijack, but this might be relevant to the OP. When you changed to HEI did you also change to a hotter plug? I assume you upgraded to 8mm wires also?

[TJ's Chevy]

Originally Posted by jdl71

Sorry for the hijack, but this might be relevant to the OP. When you changed to HEI did you also change to a hotter plug? I assume you upgraded to 8mm wires also?

On my 305 V6 with a 4 barrel, I stayed with stock type NGK plugs and stock type wires and installed a pertronix. Hardly if Ever pops on deacceleration now.

On my 292 with a 600 cfm edelbrock I installed an HEI, Napa 8 mill wires and 1 step hotter on the plugs.

The 305 V6 has been burning the fuel without issue so I haven't seen the need for bigger wires or hotter plugs.

[hevymetl]

Originally Posted by jdl71

Sorry for the hijack, but this might be relevant to the OP. When you changed to HEI did you also change to a hotter plug? I assume you upgraded to 8mm wires also?

hei was done by po. Ill have to check plugs to see which ones they are. it has 8mm wires.

[gabbin]

I actually love that sound!