66 Sat
Well-Known Member
So I collected my car this morning after having custom headers installed. Engine is a 354 cu poly stroker, 10.8:1, Ross pistons, 600 Holley vac sec, manual choke wired open (have never needed it in this hot climate).
Car started fine and idled ok but after a few minutes driving I noticed a slight surging or missfire. I pulled over and checked all the plug wires were on and were not crossed over - all good. I continued driving home and car started backfiring occasionally through the exhaust at a light throttle (2,250 rpm). Once the car was fully warm it went away and was fine for the remaining 45 minutes on the freeway at 3,000rpm. I did pull off the freeway to be able to get back on from a standing start - wow, the headers have really opened up this engine - again no issues. It was also fine cruising the last few miles on a light throttle from the freeway to my house too.
Questions:
1. Is the surging/backfire because of a lean condition since the headers were fitted, made worse on a cold engine? The old manifolds were very restrictive and the engine was being strangled. If so how do I fix it?
2. Will I do any damage driving it around like this until it's fixed, bearing in mind it only seems to do it from cold (although I can't confirm this yet as I've only driven it once)?
I'm not an expert in tuning at all.
Thanks
Car started fine and idled ok but after a few minutes driving I noticed a slight surging or missfire. I pulled over and checked all the plug wires were on and were not crossed over - all good. I continued driving home and car started backfiring occasionally through the exhaust at a light throttle (2,250 rpm). Once the car was fully warm it went away and was fine for the remaining 45 minutes on the freeway at 3,000rpm. I did pull off the freeway to be able to get back on from a standing start - wow, the headers have really opened up this engine - again no issues. It was also fine cruising the last few miles on a light throttle from the freeway to my house too.
Questions:
1. Is the surging/backfire because of a lean condition since the headers were fitted, made worse on a cold engine? The old manifolds were very restrictive and the engine was being strangled. If so how do I fix it?
2. Will I do any damage driving it around like this until it's fixed, bearing in mind it only seems to do it from cold (although I can't confirm this yet as I've only driven it once)?
I'm not an expert in tuning at all.
Thanks