so i just got a 1978 Camaro Type LT with the origional 350 in it but it's backfiring/popping thru the carb, is this a relatively easy fix? i have a video here: Help! holley 4150 popping/backfire thru carb - YouTube

 

Timing is off. Try timing it again

 

okay I'll see what happens

 

Just make sure cylinder 1 is at tdc and the dist is pointing to it. Now you have your base you can adjust from there

 

Loosen the distributor clamp slightly, so you can adjust the distributor. Mark the shaft to the intake location before turning it. Then start the engine and bring the rpm's up to where it begins to pop back. Turn the distributor slightly either way until it stops popping. Then tighten the hold down clamp, and test drive it. Be sure to check starting also, to make sure it starts easily too.

 

Was this with a hot engine? I see the choke butterfly is almost all the way closed.
It should be straight up and down when warm, otherwise it will cause the engine to sputter......kinda like it is now!

 

when I opened the choke all the way it idled way better! but when I was giving it gas, it was still popping. is it a bad carb intake combo?

 

I tried this, didn't seem to help, I also live in Colorado, would altitude have any effect on this popping?

 

Do you know how to check your float levels?

 

no, I'm new with hollies, or carbs in general, but I would like to know how to.