power valve

bax · Sep 13, 2009

I put a stock power valve into the motorcraft 2v carb. It was in the rebuild kit. I was tuning the idle screws and noticed the vacuum was on the low side. Bumpy cam. So I am sure I am too rich at idle, (Kinda stinks like fuel) Question is are motorcraft power valves the same a holley power valves? If not can you buy a motorcraft power-valve on a card / separately?

oleguy74 · Sep 13, 2009

what did you see as far as vac?they should be the same.value should be stamped on valve.if it is a #65 valve,it opens at 6.5 in of vac.i think stock value will probably be 65.also make sure you don't have a vac leak.also make sure gasket is seated properly on valve.

bax · Sep 13, 2009

I had 11 # at idle with a standard trans. So I think you are correct about the stock power valve being 6.5 But half of 11 would be 5.5 so the valve is open at idle causing my stinky idle. If I had put a stock cam back into it I am sure I would be good with a stock power-valve. I think I just need to find a 55 power valve and give it a try.

broncnaz · Sep 13, 2009

A 6.5 power valve should not be open when idle vacuum is 11in. You might have another issue.
I chose the power valve opening point by making sure its lower than the vaccum reading at cruise RPM's on flat ground. You want the power valve to open when the engine needs the extra fuel like when puling a hill. But 5.5 might be good for you with only 11in of vacuum at idle.

bax · Sep 13, 2009

yeah your right, the valve is not open at idle. It has # 54 jets in it. I dont think these are too big. I checked the float level and it is low if anything. It's just stinks like gas at idle. I pulled the plugs and they are not even coloring the electrode. I may have just a bit of tan color. Where is the extra gas coming from?

broncnaz · Sep 13, 2009

Unless the power valve is bad but then I would think that your plugs would be black. A power valve is about equal to 6-8 jet sizes. #54 jets should be fine it wouldnt matter at idle anyways as the idle restrictions are smaller.
Big cams do have a tendancey to have a rich exhuast smell as the exhuast valve is usually still open when the intake is opening.
If your idle changes when you turn the idle mixture screws then I would think your power valve is fine.

power valve

bax

Old Member

oleguy74

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bax

Old Member

broncnaz

Bronco Guru

bax

Old Member

broncnaz

Bronco Guru

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