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Old 07-17-2008, 10:02 PM
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Rich at cruise, lean at WOT

I'm doing some fine tuning of my carb. It's a 750 double pumper.

I just got a innovate wideband, and I gotta say it is awesome for carb tuning. Here's where the air/fuel mixture is at now:

Idle: 14.5
Cruise: 12.5
WOT: 13.8

The primary jets are 71, secondary jets 85

So I'd like to lean out the cruise and richen the wot. The carb has removable air bleeds, but I haven't experimented with air bleeds before. I figure the simple way to tune this carb would be to jet a bit smaller on the primaries and a bit bigger on the secondaries. Is it possible to have too much difference in jet size between the primaries and secondaries? And if so, would I be better off changing some of the air bleeds also/instead?

My targets af ratios are:
Idle: 14.5
Cruise: 14-15
WOT: 12.5-13
Do these seem reasonable?

81 Grand Prix, 355, 700r4, 8.5" 4.10
64 Oldsmobile Jetstar, all original
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