dartman59
Well-Known Member
Quick Fuel 780 SS on a 408 small block. The other day, the motor "bucked" when starting--not sure what happened; I may have released the key for a microsecond and then re-engaged the starter; maybe a tad to much initial timing--and ever since then my carb's been very lean but only intermittently. I have O2 sensors in both header collectors so I get an instantaneous display of how things are running. Normally, I run on the rich side, at both idle and cruise, 12.5-13.5. When it goes lean, it's 15.5-16.5 at cruise, and about the same or even leaner at idle (makes for a rough, uneven idle and sometimes stalls when coming to a stop sign).
It'll run lean for 2-3 outings (this my daily driver), then mysteriously go back to normal. I thought for awhile that if I put it in neutral and punched it, so it went up to the rev limiter and then back down, that doing such would clear it, but I don't think that really works because it doesn't consistently make a difference. The first time I did that, I did it because I was pissed off at the situation, and much to my surprise it went back to normal after that. Probably a coincidence.
I'm stumped. Oh-when it bucked, I saw a puff of smoke come from under the hood. It didn't backfire. Thanks for any ideas and suggestions.
It'll run lean for 2-3 outings (this my daily driver), then mysteriously go back to normal. I thought for awhile that if I put it in neutral and punched it, so it went up to the rev limiter and then back down, that doing such would clear it, but I don't think that really works because it doesn't consistently make a difference. The first time I did that, I did it because I was pissed off at the situation, and much to my surprise it went back to normal after that. Probably a coincidence.
I'm stumped. Oh-when it bucked, I saw a puff of smoke come from under the hood. It didn't backfire. Thanks for any ideas and suggestions.