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Strange power valve
Posted: Sat Nov 16, 2019 4:59 am
by Calypso
Anyone know what this is?
Stampings 12 & C-8
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Re: Strange power valve
Posted: Sat Nov 16, 2019 5:21 am
by mt-engines
2 stage power valve
Re: Strange power valve
Posted: Sat Nov 16, 2019 6:51 am
by mag2555
I would not trust those 2 stage valve for long in performance usage !
Re: Strange power valve
Posted: Sat Nov 16, 2019 9:31 am
by rebelrouser
yep two stage power valves, have not seen one for a long time, back in the late 70's I worked at a Chevy dealer, back then the dump trucks still had gas engines, 366 and 427 big blocks. Used to overhaul a lot of the dump truck holly carbs with a governor, and they all had two stage power valves similar to those in the pictures.
Re: Strange power valve
Posted: Sat Nov 16, 2019 1:12 pm
by engineguyBill
The Holley two-stage power valve was also supposed to be able to withstand diaphram damage due to backfire much better than the original design power valve. Not sure if they are successful in this or not, BUT the two stage PV is not suitable for high performance applications.
Re: Strange power valve
Posted: Sat Nov 16, 2019 2:32 pm
by Walter R. Malik
2 stage power valve would not blow-out as easy however, when wide open could not pass enough fuel to supply more than 2/.062" PVCR's.
The first stage would open at about a drop to 10 to 12 inches of vacuum and supply about only 2 jet sizes of extra fuel so mileage could increase and emissions would be less on the road because using slightly leaner main jets were possible.