Thread: Can I tune out this bog?

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Hi Denny,

Manifold vac is low (~5") at idle with 6.5" power valve. I just got a longer hose for my gauge today and was going to see what the cruise and mild acceleration vac are tomorrow. I've heard a couple different stories... the holley performance tuning book I'm reading says to pick power valve 1-2" less than vacuum under normal/mild acceleration, but I've read elsewhere to pick it below idle vac...

Is it not true a lean bog usually means power valve opens too late, or pump shot is too small?

Erik suggested I go to a 3.5 valve based on my low idle vac (thanks Erik!) but now I'm not sure what to do... maybe it will be clearer when I see vac under "normal" driving conditions.

Do you think it's worthwhile to fiddle with the pump shot for this problem?

I still have the stock nozzles for this carb even though the jets are 4 sizes bigger (and usually, you jet down about 3 sizes from sea level to Denver)

Thanks,

Chris