Hey guys. I have a 400 in my 79 that I'm rebuilding and I have a backfire issue. When easing into the accelerator, everything is fine. But when you romp into it, when the four barrels open, it pops really loud. I checked to see if my distributor was advancing but I found that the c clip was gone and the arm wasn't attached. I fixed that and it still pops. Wondering if I can get some ideas from y'all!

~Payton K.

 

Sounds like you are not getting enough fuel discharge from the accelerator pump. Did you rebuild the carb? If you did, then it should be a simple linkage adjustment to get more stroke. If you didn't rebuild the carb, now might be a good time. You used to be able to buy the plunger by itself, but I'm guessing now you have to buy a complete kit. Good luck.

 

I didn't think too much about the carb because it is fairly new. But I had the thought run through my head. I'll have to look and see what I can find out. Thanks!

 

Well, I think I got things figured out. My vacuum pot on my distributor wouldn't hold a vacuum. I change out pots and re-timed everything. When timed 10º advanced, you could wrap it all the way up. But when I shut it off and started it it kind of struggled. I hope now its just a matter of getting things timed right.

 

try setting teh timing @ 6* BTDC