HOLLEY blown power valve??

[RECHRGD]

I've got a Holley 750 double pumper on the 440 that's about 5 years old (20K miles) that came with the blow out protection for the power valve.  At the end of this season it just started running really rich without any change in adjustments.  wet black plugs, stinky exhaust, etc..  It sure seems like a power valve.  Do they fail very often even with the blow out protection?  Maybe I should just buy a complete kit and do a rebuild on the whole thing.  That would be a new experience for me.  Thanks, Bob

[Runner]

hi bob.   ive only seen a couple bad power valves, i think they get blamed for alot of other carb problems.  get a good kit and go for it. i prefur to use the holley kits and while the holley strip kits are nice, they cost way to much because they come with enough stuff to rebiuld a couple carbs.  no need to pay for needle and seats for side pivot bowls.      make sure your air bleeds arent pluged.

[RECHRGD]

Thanks, Mike.  I'll just pick-up a kit and see how talented I am.  Bob

[Runner]

if you get in a jam,  dont think twice about giving me a call, or if you really get in a jam, though it in a box and come on down and we can get it back together.

[RECHRGD]

Thanks Mike!  I doubt if I'll be driving down there though.  By the time I paid for the diesel for my pick-up, I could probably just buy a new carb.   
.

[Chryco Psycho]

often you just need a new PV & gasket & it will fix it , I doubt you need to rebuild it , retighten the bowl a couple of times with the new gasket

[RECHRGD]

OK, Now that the holidays are over I finally made it out to the shop.  The power valve looks fine.  Is there anyway to tell if it's bad?  It seems to move freely with only the springs resistance and seems to seat OK.  The diapham looks OK, but no way to tell for sure.  Thanks, Bob

[Runner]

this sounds nasty but suck on the end of it  and see if it leaks. 

[Chryco Psycho]

I agree
could be just the gasket between the metering block & body was leaking , was it wet in the vacuum port inthe main carb body when you disassembled it ?

[RECHRGD]

OK, if I suck on the diaphram side, I get alot of resistance, but it does seem to leak and there's no movement of the valve.  If I do the valve end, it seems tight.  I'm just going to assume that it's bad.  I'll replace the gasket also.  I'm glad nobody took pictures of me performing this test proceedure.    Thanks, Bob

[8WHEELER]

  The good old ''suck'' test, done it many times, it should not bleed down on the non plunger side
while holding a vacuum. The plunger on the other side should suck in and stay there as long as the
vacuum is applied, sounds like a bad valve at least, yes a new gasket is wise, unless you are using the
new reusable gaskets they are very good.

Dan

[Chryco Psycho]

if the valve is not moving replace the PV

[RECHRGD]

OK, today I go to the local speed shop and try to buy the power valve and gaskets that I'm after.  The price for the parts was more than a total rebuild kit.  I buy the rebuild kit and bring it home and discover that there are three power valves.  The instructions show a power valve in both the primary and secondary sides. the carb came from the factory with only a power valve  in the primary side and just a plug on the secondary side.  I'm confused and dismayed. 
do I just replace the 6.5 valve in the primary side or what?  Thanks, Bob

[Runner]

bob,  some holleys have the valves front and rear.   just replace the front one.   just out of curiosity did you try your local shucks?   they have 6.5 valves on the shelf for around 10 bucks i believe. i also try to always use genuine holley parts. 

[RECHRGD]

Mike, The valve was not that expensive.  The gaskets and washers I was after added up to around forty dollars when the valve was included.  The rebuild kit was around $43.00, so it was a no brainer to me.  Bob

[Chryco Psycho]

jsut repalce the front PV
here are you buying parts , a pair of agskets should be 6-8$ & a PV is 8-10$

[RECHRGD]

Neil, I also wanted to replace the small washers for the bowl bolts (.  They came only in a package of about 20 for a give away price of $19.00.  That was the deal breaker.  This was at the 'General Store' in beautiful downtown Spokane Washington.  Bob

[Chryco Psycho]

makes sense now !!