My pv flutters when it 1st opens getting the lean pop. I want to block off the stock vacum port. Convert to a brpv then plumb a boost referenced mallory 4309 regulator to the pv cavity to open the brpv by fuel pressure. I know it can't be this simple,what am I missing?

 

You need a solenoid (switched on/off by Hobbs switch in the hat) to control fuel pressure being applied to the PV cavity instead of an extra regulator.

 

Like this?

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That is exactly what I was looking for. More info please. What is the Mallory set to? Does that setup work better than the solenoid/ hobbs settup you had?

 

https://www.theturboforums.com/smf/carburetor-boost-tech-questions/cane-power-valve-actuation/

 

It did not work for me. The reg was set at 11psi, but it would not seal well. It would go rich under light excel. A different type valve would probably work great, but my Mallory reg did not work for me. The Hobb/solenoid combo is very consistent. I believe with the right valve it would be a great set up. I just did not feel like messing with finding a suitable valve.

 

Thanks for the help.

 

Keep us posted if you try it. Success or failure can inspire new ideas.

 

Sorry for resurrecting this old thread, but I'm curious about a couple of things. First.....Brian - are you still "crutching" your BRPV's with solenoid-activated fuel pressure? The reason I ask is because I've been reading a lot of archived posts about others (like Blown385) needing 25+ psi to fully open theirs and, obviously, the pressure differential between boost/bowl pressure and needle/seat-friendly fuel pressure is only gonna be 5-7psi in most cases.

Anyway, I like your overall strategy, especially the feature of using the "bleed" hole between the PV cavity and the fuel bowls to not only bleed off pressure when it's not needed for crutching the PV, but also to augment the needle and seats by adding fuel to the bowls during boost! But, if the 5-7psi f/pres isn't sufficient to fully open the PV's in your most recent iteration......then it's a moot point. Which brings me to my second question: WHAT IF......you used a ganged pair of "dead-head" FPR's (like THIS), with one set to 30-40psi for PV activation and the other set to 5-7psi, to keep the bowls filled?

I'm suggesting "dead-head" FPR's for this proposal, because it allows the use of just one f/pump - whereas the use of by-pass FPR's would not allow two different f/pressures.......since - as pointed out to me several months ago by Cat Herder - the pressure everywhere in the system (except the return line) is the same. Therefore, if by-pass regulators were an absolute necessity, two separate f/pumps would be required to supply the two different pressures.

BTW - I'm not trying to reinvent the wheel, since I consider air-pump/CO² "crutching" to be a brilliant strategy. I'm just throwing this out there as a possible alternative and - as said - it gives the added bonus of providing a secondary path for fuel to be added to the bowls under boost.

C'ya - RAY

 

Sorry for such a late reply. The Hobbs switch and solenoid cane system works great with only fuel pressure. The crutch doesn't need any more pressure over the max boost than the cane. I believe blown385 uses more than 25psi to keep his open since he runs over 20psi intake pressure. The way I do it the pressure rises with boost. If I ran 22psi boost, I would have nearly 30psi on the pv. If boost gets out of hand the pv is more likely to stay open using fuel pressure because it will compensate. Using air pressure also can be hard on baseplate gaskets since the pressure differential is higher at at lower boost during transition. I only have heard of one person having trouble, but there may be more.