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Old 01-18-2012, 04:13 PM
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Power valve vacuum source goes to the intake manifold plenum below the blower.
Preferably with a in line one way check valve to avoid boost pressure acting on the power valve diaphram(s).

Same with the trans vac modulator, to the intake manifold under the blower with a in line check valve. A mechanical (cable acted) trans modulator is another way to work the trans shift pressure. Get one from a GM desiel van w auto trans.

The Rich idle and hot header tubes is mostly caused by a lack of initial spark advance timing at idle. Roots supercharged motors need a lot of timing at idle.

You need to shorten the mechanical advance curve to allow this.
You need a 10DEG or less timing curve.
Fix the timing curve to allow this.

If the blower motor has a fair big cam just lock out the mechanical advance curve and set the locked timing at 28-30 deg BTDC. (street Blown on pump gas, without boost timing retard)

If you are using boost retard, set the locked timing at 36deg BTDC at idle and take 6 to 8deg timing out with the boost retard box, under boost WOT

A roots supercharged motor will idle much cleaner with a generous amount of spark advance at idle. The bigger the camshaft, the more timing it will like at idle. 26deg +++ @ idle

Last edited by F-BIRD'88; 01-18-2012 at 04:21 PM.
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