Humor the GM guy

[Anonymous]

Actually I'm not a gm guy but I'm modifing a GMC truck. What I have is a very well running 2.8v6 s15 with low mileage. It has a varajet carb on it that is working well enough to give me mid 20's gas mileage. However the truck couldn't pull the skin of an onion. I think it's rated at 105hp or something. I have a t3 lying in the garage that is in good working condition that I'd like to setup to blowthru the varajet. I'm going to run about 5-7 psi to start with but I'm having trouble with how I'll deal with the secondary enrichment. The carb will be taken apart, rebuilt with all shafts sealed and the vents plugged. The secondary is progressive with erichment occurring with the airvalve opening which is controlled by the opening on the secondary. What effect will boost have on the airvalve if the secondary throttle plate isn't open? Will the powervalve cause fuel to build up on the secondary before it's open which will then cause a big bog when the throttle is opened enough to allow the fuel into the intake? Has anyone used a carb that operates like this in a blow thru setup? In Hugh Mcginnis's book he states that the secondary airvalve should be referenced to boost, any ideas on that? I have a few ideas but I'm not sure on what would work or it's been done before.

Bernard

 

[Anonymous]

I am thinking you might need to build a box around the carb.

It has been 15 years since I messed with those ('86 Celebrity 2.8) I don't remember enough about them to make any recommendations.

Unless you are really up on carbs and are practically a "guru" I wouldn't try to mod that carb. But if you are a whiz, then go for it!

 

[Anonymous]

Just trow that varajet awy and adapt a holley 2 barrel to the manifold and save you a lot of headaches

Other than that it's just the usual, Upgrade the fuel pump and get a boost referenced fuel press. regulator you can use a mallory (erhh don't have the P/N so the boys can help me here) and tune the power valve and jets.

With the holley you don't need to build a box around the carb just get a good bonnet.

Hope this helps