Backfire.....
Thread Starter
Race Director
Joined: May 2004
Posts: 11,920
Likes: 2
Backfire.....
Something I want to throw out there to you guys....
Vortech s/c carb blow through) 540BBC with Dart Pro 1 aluminum heads.
Running probably 5 lbs boost.
When the car is cold it backfires every 5-10 seconds out the driver's side side exhaust. When the temp gets to 200 degrees the backfire disappears completely.
I don't have a choke. I use a 220 GPH fuel pump regulated to 6-7 psi.
A/F ratio (bung in passenger side) stays between 12-14 idle....I should double check that statement though. I believe (as far as I remember) that it goes to 15 on the highway.
Does this has anything to do with the 345cc heads or is it a plug issue.
I don't understand why it only backfires when the car is cold....
Vortech s/c carb blow through) 540BBC with Dart Pro 1 aluminum heads.
Running probably 5 lbs boost.
When the car is cold it backfires every 5-10 seconds out the driver's side side exhaust. When the temp gets to 200 degrees the backfire disappears completely.
I don't have a choke. I use a 220 GPH fuel pump regulated to 6-7 psi.
A/F ratio (bung in passenger side) stays between 12-14 idle....I should double check that statement though. I believe (as far as I remember) that it goes to 15 on the highway.
Does this has anything to do with the 345cc heads or is it a plug issue.
I don't understand why it only backfires when the car is cold....
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
That's usually a sign of a lean condition: When the engine is cold, it needs a richer mixture to run correctly. Since you don't have a choke or other enrichment for the cold condition, the engine will run lean, and you'll get some popping in the exhaust until the engine reaches normal operating temp.
Lars
Lars
