Need A Electric Quadrajet Expert

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Oct 20, 2006 | 11:35 PM

jayr

Thread Starter

Instructor

Joined: Dec 2005

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From: Burlington WI

Need A Electric Quadrajet Expert

Not sure if this the right forum to ask this question as the 81 corvette
was the only year that used a electric carb. I am going to rebuild my
carb as I thing the float is soaked and purchased another from ebay from a
1985 305 engine. This one has a gray plastic cap for mixture solenoid
and mine on the car has a blue cap. As I only going to run this 85 carb
while I am rebuilding the original, is there any difference between the two or will I have to make adjustments if there is. I know many other
GM models ran the electric carb thru the late 80's. I suspect the rods
have a different number ,but only use the ebay carb for moving it around in storage.

Oct 21, 2006 | 08:48 AM

Dalannex

Safety Car

Joined: Mar 2000

Posts: 4,078

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From: Northeast South Dakota

There could very well be difference. There is another "electronic" q-jet out there that was used in many 85-86 trucks, and possibly other applications as well. It is not the same as the E4ME. The difference is clear if you take the top off. I think looking at the top you can see the difference too, but don't remember for sure. The E4ME has a mixture control solenoid that constantly opens and closes the primaries by pulling them down in their seats for a specified amount of time. The leaner you need to be the longer the primaries spend in the down position. This length of "on time" of the mixture control solenoid is how the carb meters the correct amount of fuel. The other carb that I have seen on trucks has a kind of secondary accerlerator pump chamber that has a solenoid plunger in it and when you step on it or when it decides it needs more fuel it energizes this plunger and puts more gas into the engine. This particular carb I am not too sure of.

-Justin

Oct 21, 2006 | 09:53 AM

tracdogg2

Drifting

Joined: Jul 2002

Posts: 1,995

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From: Garland Texas

Justin,
You are close on your description. The solenoid on the truck carb allows a bigger shot of shot of fuel when the engine is cold. Once it's warmed up the solenoid restricts the shot from the pump. The solenoid is controlled by a temp sensor. The ESC has no control over it.
Mike

Oct 21, 2006 | 10:18 AM

Ganey

Race Director

Joined: Apr 1999

Posts: 11,520

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From: CORVETTE 77 385 C.I. TEXAS

I checked the sec. rods on a 86 SS 305 el. Q-J & as I recall they were same as used on some 350s. If you were going to run the car w/ it the sec. rods & hanger would be easy to change from top. Obviously one should also check the primary rods & jets, though the el. solenoid may make up for a small difference.

Oct 21, 2006 | 10:30 AM

Dalannex

Safety Car

Joined: Mar 2000

Posts: 4,078

Likes: 27

From: Northeast South Dakota

As long as you know the secondary rods and hanger are the same (which like Ganey said, is easy to check from the top) I wouldn't worry too much about the primaries from the start. You can check to see if the primaries are relatively close or not with an analog dwell meter on the dwell lead of the wiring harness. If you are getting a real long on time you could assume that the jets are too big, a real short on time and they're too small. I would guess that they are close enough that nobody would notice a difference.

-Justin

Oct 21, 2006 | 11:35 AM

a1sensei

Melting Slicks

Joined: Mar 2006

Posts: 2,465

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From: Orange Park Fl

You should be fine. I heard someone once say that there is a difference between the blue and black connector carbs, but my '81 came stock with black, and I know a lot (like yours) came with blue. I've been working on them for a while and they seem identical. The primary rods and jets are not an issue, the mixture control solenoid compensates the A/F ratio automatically (It's a beautiful thing). I'm not even sure they made different size primary rod and jets for these carbs. The half dozen or so that I've rebuilt have all been the same. God bless, Sensei

Oct 21, 2006 | 11:49 AM

tracdogg2

Drifting

Joined: Jul 2002

Posts: 1,995

Likes: 110

From: Garland Texas

If your carb has a three terminal plug on the left front then it is a CCC carb from a car. This is the tps terminal. If it doesn't have this then it is a truck carb.
Mike

Last edited by tracdogg2; Oct 21, 2006 at 11:51 AM.

Oct 21, 2006 | 05:32 PM

jayr

Thread Starter

Instructor

Joined: Dec 2005

Posts: 196

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From: Burlington WI

Thanks for the infro guys. This is a great forum for a guy that is continuing wrenching on the C3's. I own a 87 wide body with a ZR1
rear deck but somehow it just does not turn me on like the C3's. The
Doug Nash Overdrive is kind of neat in the 87, but the body style just
is not there like the shark. Jayr