Robert N

Rejetted the Holley 650 Dp primaries last weekend from 67 to 71. Took her for a quick spin and all seemed OK.

Drove her this morning. Was about 46 degrees. She was a little sluggish off the line. At 2500 RPM she bucks (fine at 2000). After running a few minutes at a given RPM range I stepped on her. There was a nothing, then launched.

Going to recheck the float as it seems like fuel shortage.

Any other thoughts?

Robert N

Floats OK. Next?

The Dude

"Bucking" at 2,500 RPM coupled with the above quote sounds like you're lean at cruise and the lean-out gets worse for a moment when you jump on it. This points me toward a couple of things.

First, the stumbling at cruise makes me think jets, but you went up 4 numbers on the primaries. Now I'm thinking vacuum leak--extra air getting into the carb at cruise somehow. Perhaps the wrong gasket on the metering block? Maybe a warped metering block? Maybe the bowl/metering block isn't torqued down correctly?

The bog when you jump on it also tells me your're lean, and getting leaner momentarily when you hit the throttle. A lot of times a bog off the line or when you goose it will happen if the shooter diameter is too small and the carb's on a single-plane intake, for example. But all you did was jet up 4 numbers so the shooters probably aren't the problem.

Look for correct re-assembly and then go back through it and check your pump linkages and levers. Maybe when you had the carb apart to re-jet it you bolluxed up the pump linkage or lever a little and it's not giving you enough shot when you goose it. Maybe one or both of your pump diaphragms are due for replacement. That's a few things to think about, anyhow. Other folks will chime in, I'm sure.

Just riffing. Good luck.


[Modified by The Dude, 11:32 AM 12/16/2002]


[Modified by The Dude, 11:40 AM 12/16/2002]

Fevre

Robert

This might help, it did for me:

https://www.corvetteforum.com/techti...=108&TopicID=3

Make sure you follow it step by step and don't skip any. :yesnod:

Robert N

Gonna start by removing and reinstalling the bowl. Might just be something really dumb.

The Dude

Yeah. Check for clogged fuel lines, clogged filter or clogs inside the metering block, too. A lean condition doesn't have to be too much extra air--it could be a fuel shortage, too. Probably something real minor. Otherwise it would have to be something that happened as a coincidence unrelated to your jet change.