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Choosing a powervalve

977 views 7 replies 5 participants last post by  406MOUSE 
#1 ·
How should I go about choosing a power valve?
 
#3 ·
I checked the vacuum with the car in gear and it was bouncing around between 6 and 7 inches. If I have a 6.5 power valve is that ok or do I need to go a lower? If is bouncing between 6 and 7 inches is there a possibility that my power valve is open when it is idling.
 
#5 · (Edited)
406MOUSE said:
I checked the vacuum with the car in gear and it was bouncing around between 6 and 7 inches. If I have a 6.5 power valve is that ok or do I need to go a lower? If is bouncing between 6 and 7 inches is there a possibility that my power valve is open when it is idling.
What are the engine and cam specs?

I would be looking closely at the whole deal to see if I could get the idle vacuum up from where it is- 6 to 7 in Hg is in the range of a pretty "big" cam, duration and overlap-wise. So unless the cam IS big, there could well be ways to increase the idle vacuum and the idle quality and off idle response along w/it.
 
#6 ·
As Cobalt kind of eluded too, make sure your carb and ignition is properly tuned before reading your idle vacuum. That is a prett low vacuum, not too bad, and there are a lot worse out there, but with that low of a vacuum I'd maybe go with even a 3.5". If it is however more around 10" then a 4.5" would be fine, perhaps too small but it will help fuel economy.
 
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