[V8Vairs] Backfire through the carb...

[Craig Nicol]

Good progress!  Don't blame the carburetor though; something is making the
mixture fire in the intake - that's not the carburetor's fault.  I view the
Edelbrock AFB very highly and as the carb of choice. Super easy to tune and
they never leak.  

Think about what could ignite the mixture in the intake.  The list includes;
crossfire in the cap or wires, wrong firing order, advanced timing, broken
valve spring, non-closing intake valve, flat exhaust cam, cam installed a
tooth off, cracked intake crossover, and probably more. Except for lean
misfire (which stays in the cylinder), the carb cannot cause an intake
backfire. 

I'd start with double checking the firing order, replacing the cap, checking
with a vacuum gauge and so-on. Have you confirmed that you have a balancer
that matches the timing cover?  There are at least two setups. Put a probe
(small screwdriver) in #1 cyl and rotate engine to TDC (according to the
probe), then see where the balancer indicates. I've had customer's cars that
backfired for each of the above reasons.  You just have to be methodical to
find the problem (and hope that you find it before you go nuts!)

Hope that helps,
Craig Nicol



  Hi:

  I switched the vacuum line to the port on the driver side. 
  The throttle response improved tremendously but, 
  still backfires...through that darn edelbrock...

  Total advance is now @ 34...

  Regards,


  Tony I.