Holley Secondary power valve ?????

[swinger340]

Advantages and disadvantages? My HP 750 came equipped with one OOTB on primary and secondary blocks, but I have always blocked the secondary PV in the past. For a mostly street driven 416 I'm trying to decide if I want to try one out on the secondary block or not. I have already done a jet swap to 76p/84s and am on the edge of putting a 50cc accelerator on the secondary side. I have only dealt with single power valve carbs in the past, so I'm leaning towards blocking it off. Anyone have a good reason as to why I should use one or not? If 2 are run should they be the same sizes or set in stages? Im kinda shooting in the dark until I get it fired up, I'm guessing vacuum may be 12-14 so I temporarily started w/ a 6.5 on the front block. Any advice and or experiences welcome.

 

[ssba]

Can't think of a single good reason for the carb user to use one on the secondary side.
Not the most dependable part in the the world for certain. Good for manufacturer selling the part.
Tune the secondary side with the jet that your engine likes. They are a must on the primary side. Not as nice of a enrichment design as the tapered metering rods in the carters, but I still only use holleys on my mopars. Great carbs.
You've been doing it correct plugging them based on what has worked for me.

 

[swinger340]

Can't think of a single good reason for the carb user to use one on the secondary side.
Not the most dependable part in the the world for certain. Good for manufacturer selling the part.
Tune the secondary side with the jet that your engine likes. They are a must on the primary side. Not as nice of a enrichment design as the tapered metering rods in the carters, but I still only use holleys on my mopars. Great carbs.
You've been doing it correct plugging them based on what has worked for me.

I have always plugged them and fattened the secondary jets. Has always worked good for me in the past. Current 750 on my 340 has 2nd block PV plugged and runs fine. Nice crisp throttle response w 70/82 jets and a 6.5 PV on primary side. Did have slight hesitation and a quick dead spot as soon as secondaries started to open, till I put the 82s in secondary side, and went little bigger on the secondary squirters.

 

[67Dart273]

Regardless that PVs could fail, seems to me that by the time the secondaries started to open AT ALL you would already "fer sure" be into the PV, therefore it's not needed.

 

[dwire67]

Block off the secondary Power valve, up it six jets size is the rule of thumb.
I would block it off put 86's or 88 jets in it, change the squiter to a 35 or 37 and put the hollow squirter screw in it. This has always worked on the carbs I do.
I have Race carb hand built by Barry Grant and I had on engine that was Dyno'd on Ray Bartons Dyno and then ran the engine with the Carb I built and the BG car only made 5 more HP than the one I did.

 

[70aarcuda]

block it off....but measure the channel diameter...calculate the area...of channel...then calculate area of jet in secondary...add them together...then work it backwards to find the diameter of the total area ...compare diameter to holley jets...

or jet up about 8 jet sizes ...