my carb is backfiring through the carb but not at idle or under hard acceleration just at any speed or acceleration over 70mph so i dunno if its timing or fuel any input

i have new fuel pump jsut a couple months old and a new fuel filter and all that good stuff so i am thinking carb jets or timing but i need some help to identify my problem

 

is the timing advanced to far ?

 

Occassional backfire usually means a bad plug, bad plug wire, or a valve that is sticking.

 

Firing back through the carb is usually a lean condition. A test from the old days was to run-up to around 4000 rpm in first and back-off the gas to see if you had that problem.

 

well i will try timing and plugs

 

sounds like your timing is retarded OR your accelorator pump isnt allowing enough fuel in..

take off the air filter and, without the car runing, look into the carb and push the gas alittle you should see it squirt into the venturi a nice even stream of fuel in BOLTH venturis, if only one is squriting or it seems to have air in it you have an accelorator pump problem.


JOSH

 

i actually retarded the timing about 2 degrees (running about 8 now) and i have noticed a major improvementi can go about 80-85 no prob now and i just rebuild the car about 2 months ago btw and it worked hunky dory past 100 with my old cam now that i have this new one i am having the problems

 

Check the ground wire inside the distributor. I had the same exact problem in my '71 F-250...

It would idle rough, cruise rough; the only time it would run 'smooth' was under hard acceleration.

Just open up your distributor cap and look for a little black wire.

 

i am using a ds2 dizzy with a msd box to power it it idles pretty decent and accelerates ok but anything after those speeds it no power and backfires through the carb i think i am gunna rejet my secondaries larger and see how that goes cause i have a feeling that might have something to do with it