I may be buying an IROC with no motor in it, and dropping in the LB9 from my 86 Trans Am. The IROC started out as an LG4 car, so id need to convert to a carbed setup. Id like to stick witha non-CC Q-Jet setup so the car can get decent mileage, as it will be driven everyday.


The question is: What type of carb should i be looking for? Any specific years that are better than others? Would a carb of a given year be the same in a passenger car and a truck?

2nd question: How would you go about rebuilding/upgrading an HEI distributor for better performance and mileage? Specific parts reccomendations would be apreciated.

3rd Question: What modifications would you make to the carburetor itself for better performance and mileage? Id be looking for a setup with more punch than stock, but wont kill fuel economy on a daily driven car.

Thanks a lot.
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Your best bet on a used q-jet is finding one off an engine that is about the same size. Truck or car. As long as the HEI distributer is working correctly(not broken) it should be fine--that's about as good as it gets. Q-jet is already a 'mileage' carb with the small primaries. For performance you need to do some adjusting on the secondaries(more fuel). Keep in mind that if you run it hard, it's not going to get good mileage. To make more power it takes more fuel

 

If you must get a Q-Jet get an Edelbrock Q-Jet. I've got my old Q-Jet sitting right beside my monitor(makes good paperweight). Look, if your going to get a Q-Jet you are going to have to do some searching. My Q-Jet has a vacuum diaphram so when there is manafold vacuum the diaphram closes and prevents the secondaries from opening.

Because I bent the Q-Jet I had to get a new one. I got the Edelbrock 600 CFM carb and it runs great. You can adjust the Edelbrock to littleraly give no gas, and then work your way up from there(as I did). The Edelbrock worked(roughly) right out of the box(gas was to abundant). I changed the Hg spring(to a shorter one) and connected everything right and wala! I pass emmisions.

 

there are tons of things you can do to quadrajets that will make them better suited for performance use, but i wouldnt bother, holleys are just too good. if you want to find out how to setup your quad, check out HP Books "modifying and rebuilding your quadrajet" i think thats the name. good book, good carb, just takes knowledge.
id get one off of a early 70s truck, at autozone reman'd for 100 bucks, you have to check which truck it is, but it has a warranty, and its cheap. its for a 350 half ton truck around the early 70s i believe.

adam

 

That's odd. I have a Hollet 4160 sitting in my garage holding down a stack of spare gaskets. It probably has less than ten hours run time on it. Like every other Holley I've ever played with, I can't get the intermediate fuel metering to work worth a crap. It seems that a "Transfer Circuit" was beyond the scope of Holley engineers. That's the nice thing about a ThermoQuad. You can adjust nearly every facet and phase of operation however you desire through jetting and metering rod changes.

 

OOPS! I was mistaken. The "mini anchor" is sitting on top of a box of ROCKERS on top of a stack of gaskets....

(Excuse the mess - I just moved and haven't organized.)

 

Vader, what do you have for lighting in your garage? Or is it just the white walls that make it so bright in there?

 

My guess would be that is a combination of lighting, and the flash from the camera.

 

LOL... I couldn't agree more!