Hi everybody,
I would like your suggestion on what I could do to have better vacuum and idle...
The carb (7041251) is rebuild (stock) by a known rebuilder in the US.
What I know: 71 jets, 49b prim.rods, AK sec rod.
Choke work well, acceleration and cruise is ok.
Engine: 1970 455 (low comp) with headers
Cam lift is .448 INT, 456EXH, unknown duration.
Compression was 135 to 145.
Base timing 14, dwell 30
Plugs are pretty white with good gap.
What I did: Did send it back to rebuilder last year and he said that he had enriched the idle a bit
but I don't see any improvement.
Idle mixture screws are out 7-8 turns
If I put my hand over the carb, rpm rise and my vacuum is much better (14 to 18)
Checked vacuum leak with carb cleaner around intake and fitting with
all hose disconnected (PCV, brake booster, trans modulator, distributor)
No leak except a little one around secondary throttle shaft.
So I really think the carb is the problem.
Is there something I can try that wouldn't need the carb to be taken apart ?
Do you think that with today's fuel, the stock spec on that carb is wrong ?
Thanks a lot.
