Adapting a non-CCC Q-Jet for turbo....

[Freddie's Buick]

Adapting a non-CCC Q-Jet for turbo....

The Patient here is a 1980 Pontiac Q-jet from a .301-4.9L engine #17080272. Listed as a 140 HP carb type (4). The mod has to be done to the throttle plate.

Drill a new port starting with a 1/16" bit straight through until you get to the vac opening in the throttle, (3/4 depth). Step up to 3/32" to the vac opening and finish up with an 11/64" bit but only to a depth of 1/2".

I borrowed a port tube from a duel jet which is .184" diameter and fits snugly around the new 11/64" opening, (.172").

I'll keep updating as the rebuild progresses.

 

[Freddie's Buick]

The bottom of the throttle plate has a vac opening that leads to the intake manifold. This has to be epoxied shut. From now on the vac must come from an external source which is at the foot of the compressor after the turbo.


The other pics show the matching ports of the throttle plate and carburetor base. With a closer look at the bottom of the carb base which leads to the APT that controls fuel mixture. :biggrin:

 

[charlief1]

Looks like I've inspired you some Freddie.:biggrin: This really does work better with an E4ME base though. No epoxy needed to do the mods and you just need the drill bits and the tube.

 

[mat231v6]

nice info.

 

[Freddie's Buick]

.....This really does work better with an E4ME base though. No epoxy needed to do the mods and you just need the drill bits and the tube.

The E4ME is a CCC carburetor, (electronic computer controlled). As Charlie stated either one of these throttle plates would work. The difference is that the E4ME does not have any vac openings for the APT.

That would mean that drilling may have to be more precise, (if you goof-up, there's always epoxy. As opposed to a non-CCC carb which already has the opening and one can use it as a guide.

One finishes the mod by sealing the bottom of the throttle plate were the original opening exits, (epoxy).

Charlie....stop inspiring me will you. How can you sleep at nights?

 

[mat231v6]

i have a really dumb question why do you need that extra port anyway? what hooks up to it?

 

[Freddie's Buick]

No dumb questions here Mat, all are relevant.
Turbo's require a different carburetor and they are very difficult to locate unless you buy one new/rebuilt if you're lucky.

The only difference between a regular carb and a turbo carb is the plumbing.
Hence this thread I started. It shows you how to re-plumb any Q-jet to do what a turbo carb essentially does.

This mod is only for a non-computerized turbo Buick. If you have a functional ECM, (computerized), turbo Buick you don't need this set-up.
The electronic carb does not use vacuum. It uses an electronic mixture control solenoid controlled by the ECM.

Many have asked about this and I figured a few pictures tell a billion words.

As for what does the port do and were does it hook up to:

....The bottom of the throttle plate has a vac opening that leads to the intake manifold. This has to be epoxied shut. From now on the vac must come from an external source which is at the foot of the compressor after the turbo.

 

[mat231v6]

This mod is only for a non-computerized turbo Buick. If you have a functional ECM, (computerized), turbo Buick you don't need this set-up

i dont have a ECM. So this mod is for me.

Originally Posted by Freddie's Buick
....The bottom of the throttle plate has a vac opening that leads to the intake manifold. This has to be epoxied shut. From now on the vac must come from an external source which is at the foot of the compressor after the turbo.

I don’t have mine hooked up like that is that a problem? Should I fix it? If so can someone send me a diagram where the vac lines go. or some pic of where to hook it up at.

 

[charlief1]

If you haven't read it Matt, here's one I started to show the differences. I don't think Freddie will mind so that the info is on the board. It shows where the passages are in the carb. I'm also going to link his to mine so that in a search, if you find one then you have a link to the other.

http://www.turbobuick.com/forums/before-black-non-sfi-tech/296382-carb-info-turbo-design.html

 

[mat231v6]

what hooks up to that port?

 

[charlief1]

The PEVR valve Matt.