Backfiring

[Guest Anonymous]

I just put a new Edelbrock 600cfm (1405) carb on my '71 Z. I have a 350 with a few bolt on mods. It definitely feels faster than it was with the old Holley, but when I start to get on it more it backfires. It also appears to be running rich. If I lean it out should the backfiring go away?

Thanks,

Nick 350Z

[Modern Motorsports Ltd]

Nick, is it backfiring/popping at the intake? Or in your exhaust? Backfiring/popping when you're getting into it is typically IME timing. I troubleshot this for quite a while once as a mild timing change of 2-3 degrees didn't change it at all...turned out it wanted another 6 or so. If it pops in the intake when you back off of it then it's commonly lean (that's how I'd set primaries on my qjet, 1/4 turn out past 'pop';^)). Just turn your dizzy a bit to advance it and try it...if improved turn a bit more, (if not a larger amount)...if all solved then pull the timing gun and see where you're at and make sure total advance isn't too high (ie. max of 38, with 36 more common). The first adjustments take a couple minutes max just rolling and then stomping on it to see and backing out and adjusting againg...and don't run it up high in the rpm, you're just testing full load at lower rpm's, ie. change from no load to full load and making sure timing is OK.

 

good luck

[Guest Anonymous]

It was backfiring out the exhaust. Weird thing is, this morning it stopped doing it. It's running pretty good now, but I still think it is rich. You can see some gas coming out the exhaust, so I guess it's pretty obviously rich. It definitely still runs better than the Holley did, though. I can't wait to get it tuned and enact my revenge on that supercharged truck.

Nick

'71 350Z