87Formula4bbl

Ok, I've spent numerous hours searching the internet for ANY info regarding a blow-thru qjet/setup, and can find absolutely nothing. I'm trying to research this because I'm thinking of possibly SC'ing my 350. I really like Saturn5's setup, how he has two m90's mounted over the valve covers, and (not to steal his idea but) I was tossing the idea of doing the same with a single m90, but right now my problem is my carb. I want to retain the cc Qjet/dist, I kind of like it and its cheap(er) to have/maintain.
I figure I'll be using a low profile carb hat, to begin with, and I can get those easily enough. Mounting the m90, I think, would not be a problem.

Soo....does anyone have any info on how I might go about doing this, or ANYTHING about this?

BTW, I would just spend ~$2000 and get the $1500 manifold-mounted (weiand I think) blower and cowl hood and get 'er done, but I've got Vortec heads so that eliminates that possibility.

So any takers?

five7kid

iTrader: (14)

Supercharging just may be what it takes to find the limits of the CC system's capabilities.

As in, something short of what is needed.

Chickenman35

Turbochargers by Hugh Macinnes would be a good starting point. Amazon.com has several copies:

Turbochargers bt Hugh MacInnes

Pretty good reference book. Covers Turbocharging but all mods necessary for Forced induction also included. Lots of other books as well.

Blowing through a Carburator Airhorn can get pretty complicated. You have to air seal the throttle shafts, boost reference the fuel bowls, fuel pump or regulator and power valve.

A much better method is to build an air tight box for the whole Carb assembly. Then you only have to reference the fuel pressure to boost pressure. You may have to boost reference the Power valve as well...but I can't remember. Aeroquip bulkhead fitting through box for fuel and an aftermarket throttle cable like a Lokar and Bob's your Uncle.

A friend of mine has a 300HP Turbocharged Datsun 510.
2000CC L20B motor running a Weber downdraft carb. He's very experienced and has been running a boxed carb for many, many years. It's a much better way to go than just blowing through the airhorn.

87Formula4bbl

I think building a box sounds like a LOT better idea. I think with a box you'd only have to boost reference the fuel pressure correct? Air pressure inside carb would be equal to 'outside carb' (but still in box), so it woudlnt make a difference. Buying a box is out of the question, I think they are quite expensive? Anyhow, this is supposed to be a DIY project, and building one doesnt seem too hard.

As far as fuel metering, fattening up the secondaries and setting the rich/lean stop higher, and richening the idle screws should compensate for the more air. Not sure if it would be within the qjet's boundaries but I know you could richen it up this way, and still have the computer regulate the primaries.

five-7, are you saying that it is nearly impossible or that the qjet cannot be compatable or would not be a good choice to use?

AnotherfastIROC

Right now I am gong to appologize for bringing this board back from the dead, but were you ever sucessful in using a CC carb in a blow through manner? I am debating on this myself and right now it's between a roots 142 and a centrifugal blower.