ok i cannont find anywhere what the factory setting are for the mixture screws. can anyone shed some light on that?
also does the power valve use a standard jet for adjusting? i read that you should increase the size of the powervalve and was wondering if a jet kit will be all that i need to do that.
TIA

 

Bottom out the screws, then turn them out 1.5 turns on each side to start.

Grab a vacuum gauge to set highest vacuum once the idle speed and timing
has been adjusted properly.

The power valve is set according to manifold vacuum at idle. Use a
power valve that is 2 in./hg. lower than the manifold pressure at idle.

 

so i should tune it for vaccume and not for air/fuel? i have a wideband and i know with tpi it liked to run a bit rich.

ok powervalve math. so i read the vaccume at idle and go 2 in less what does the /hg mean?
i appoligze for not being too mechanicly informed

 

Vacuum will be the true test. AFR monitors don't tell you how the engine
is running, they just throw out a ratio.

No worries. In./Hg. is the scale on most vacuum gauges. It's "Inches of
Mercury".

You might also see KPa on some gauges. If that's the case, you'll have to
convert the values. Power valves from Holley are rated in In./Hg.

 

thanks so much. ill have to hook up the guage here in a bit and post again.

So while turning the screws i am looking for when i get the best vaccume, and i supose i will see it drop off and know ive gone to far. then when that is done take that number minus 2 and thats the power valve i need?

once all that is done, will changing the jet sizes make me need to re do all of this?
finnaly added sig maybe it will help

 

The motor will either begin to shake, or the vacuum will drop if you're out
of the sweet spot.

You may have different settings for each side depending on the carb
calibration and fuel distribution to all cylinders on the left and right banks.


Correct. You don't NEED to change the power valve unless it's too close
to the guage reading, or over the guage reading value.

If you read 10 in./hg. on the gauge and you have a 6.5 power valve
that's fine. You can install an 8 power valve to dial in the enrichment
circuit, but that's for fine tuning and power tuning purposes.

No. Those are independent ciruicts for the most part.