backfire through carb?

[1BAD68]

My just rebuilt 390 stroker runs great but when I give it a full throttle snap on the pedal it goes POW! through the carb with about a 10" yellowish white flame.
I would think a backfire through the carb would be from the timing too far advanced but its at 10 degrees at idle.
I have a Edelbrock 600 and it didnt do this before the rebuild, any suggestions?

[69chargerR/T]

Its probably to lean, the eddy 600 I think is now to small for your 390 stroker. A lot of guys on this site me included are not fans of the eddy carbs I'd get a holley carb for it, maybe a 700 or 750 cfm. Maybe some other guys will chime in on a cfm recommendations

                                                                                             Alan 

[John_Kunkel]

I agree that the pop is the result of a lean condition but not because the carb is too small.

Have you checked the accelerator pump for proper operation? IMHO the Carter/Edelbrock has a lousy pump shot even when working at its best.

[69chargerR/T]

1BAD68, what are you running for a cam in your stroker, 10* of timing may not be enough it may want more timing like 12* to 15*.

                                                                                Alan

[tan top]

sounds like it is lean

[1BAD68]

1BAD68, what are you running for a cam in your stroker, 10* of timing may not be enough it may want more timing like 12* to 15*.

                                                                                Alan

its a CompCams 269 duration/440 lift
I'm thinking it may be lean also, I had to turn the mixture screws out a ways when I broke it in.

[ChgrSteve67]

I had a similar problem with my Charger and it was because it was not getting enough timing at WOT.
I have been told and set mine to 36 to 38 degrees @2500 rpm + and the problem went away.

Check you timing, your vacuum advance and mechanical advance. Maybe something is a miss there.


Steve (Still fighting problems with my FI system)

[resq302]

I ran into a similar problem like that with my dads el camino.  The freshly rebuilt carb was leaking interally and puddling up raw fuel in the intake.  It would run ok until you floored it and then you got a fireball out of the top of the carb when it back fired.  Taught me to never be in front of the car when I was doing that type of work again as it hit the under side of the hood and rolled outwards towards me.  Lost all of my go-tee, moustache, nose hair, and singed the hair on my eye brows and front of my head pretty good.  Pretty much one of those life experiences that I will never forget.  Neither will my wife as this was a month before our wedding.   Mind you, this would have been REALLY bad if I had been looking down the carb when I was revving up the throttle manually.