setting up Q-jet for supercharger use?

[32fdcoupe]

what needs to be done on a Q-jet to run on a 355 sbc with all forged internals and a weiand 142 blower that makes 6-8 psi boost,compression ratio 8-1,AFR aluminum L98 heads 75cc combustion chambers,195cc intake runners,2.05 in/1.60 ex valves,hyd roller cam in dur @.050 213/ex dur @ .050 217,valve lift with 1.6 rockers in .517/ex .528,lobe separation 114,I have your book and have redone a handful of basic rebuilds with great success,but never built one for blower use,so any help is greatly appreciated, I will be using carb #17081206,had a Holley 750 mech on it with an adapter to mount on the speadbore blower configuration,so why not get rid of the adapter and Holley and bolt a properly set up Q-jet right on the blower right?   

[Cliff Ruggles]

The factory routed vacuum to the power piston externally thru the baseplate on turbo carburetors, and use a valve in the line leading to the PP.  This was done to keep from pressurizing the carburetor bowl when under boost.

The carb can also be set up to run straight off the jets, which eliminates the power piston.  I've set up a good number of carbs for boosted applications in this manner with perfect success.....Cliff

[32fdcoupe]

ok,so it sounds like running straight off the jets is the simplest way to proceed,what jets would you recommend?I would think they would be a lot smaller than the 76 jets in there now as the metering rods would be gone,anything to plug for the PP vacuum signal?looking at doing reciepe #2 modifications,any further suggestions would be greatly appreciated as I  would need to order the parts from you,Thank You in advance for your help and printing a easy to follow book!

[Cliff Ruggles]

I'll look at everything you are doing and spec out the jets and also supply a plug for the power piston hole.  We're here 8am-4pm, M-F EST...tks...Cliff

[32fdcoupe]

sounds good cliff,a little more info on engine build a vehicle,5.7 H beam rods,3.48 stroke,-10cc reverse dome pistons,car is fiberglass body 32 Ford on a custom TCI chassis,2650 lbs with me and a full tank of fuel,TH350 trans with a shift kit,narrowed 9 inch 3.70 gears with 31x16.5-15 mickey Thompson sportsmans,if you need any more info please feel free to ask,I know your suggestions will be a good base line to start and may need some final tuning and adjustments.   

[Cliff Ruggles]

I can provide a good base-line based on carburetor number and application.  LOTS of variables with pull-thru boosted applications, so there will be a learning curve on the other end of the deal in most cases.

Cam choice looks good, wide LSA and little overlap is best for what you are doing........Cliff

[32fdcoupe]

Agreed, I trust and value your opion and experience, figured I would get a few sets of jets above and below your recommendation, same with secondary hangers and rods.It took me several months to get my 76 Trans-Am 468 Pontiac to idle like a computer car,haul the mail and melt the goodyears without hesitation, but like I said never done a Q-jet for a blower application, but I'm not afraid to tackle it, just hated to see that holley sitting on a spreadbore to squarebore adapter on top of the blower! And I like to see the perplexed look on the Q-jet haters when I can run circles around them and idles perfectly!