here is the combo i am currently running sbc 355 with forged pistons trick flow g2 twisted aluminum heads custom grind cam hyd roller 225/235 dur at .050" .505 int and .530 lift with a 115 lsa headman long tubes into a custom y pipe and slp loudmout exh with magnaflow mufflers msd 6al built 700r4 with a ati 3500 stall converter put a B&M 144 on top of that ive been reading alot about power valve referencing etc etc but i have a quick fuel 750 carb i would like to use instead of spending 500 bux for a new carb. if i could get some info or technical help i would appreciate it thanks

I have a proform setup for blow thru with the hanger 18 mods. Took several hours to complete, typically a carb shop gets $200 to convert it to blow through. Mine is for sale actually, I need a 850 or 950 carb now for a different combo. You have to drill out the PVCR passages, remove the power valve blowout protector among a bunch of other changes.

this is a draw thru roots blower..............i think they are set up different from a blow thru application

oh your original post didn't state that. theturboforums.com is a good site that would have that info.

fixed it sorry lol here is a pic

how do you like your 3500rpm stall with that blower/700r4 combo? I have a th350 in my velle right now with a 3500 and 3.36 gears and considering 700r4 swap. Pro charged blow through carb was easy to mod myself. runs good/ goes 11's. I considered that blower also during my purchase of the pro charger.

If the engine pulls good vacuum at idle you don't necessarily have to convert to a boost-referenced power valve. There is no way to boost reference the QJet I use on top of my engine and it works fine.

I did testing on my engine with TWO vacuum gagues. One hooked up above the blower (at the carb) and one below the blower (manifold vacuum/boost). I found that there was a fairly consistent point at which vacuum above the blower equaled boost below the blower. That point was right around 5" of vacuum at the carb. At that point, pretty much regardless of RPM, the manifold would just start to tip into boost.

Since you want to make sure the power vavle is open (enriching the mixture) any time the engine is seeing boost, I installed a power piston spring (QJet equivalent of a Holley power valve) that would open at about 7" of vacuum. That way I knew that the mixture was being enriched any time the manifold was into boost. It's worked well on my mild combo for years now.

This won't work on a combo that pulls very little vacuum at idle/part throttle. The power valve will just be open almost all the time as you drive. But on a mild, streetable combo with a small displacement blower it's a good compromise without going to the effort and expense of boost referencing the power valve.

Is this what your looking for?

Check out this thread...
http://www.thirdgen.org/techboard/ca...ferencing.html (Carb Guru's - Manifold referencing a Power Valve Q's...)

you shouldn't need a blow thru carb if the carbs on top of the blower it won't see boost only if your runnin centrifugal chargers then you would need a blow thru cause the carb then would be pressurized