Surprises re: "Stock" 81 engine/carb

[Voodoo81]

Was getting really upset about rough starting requiring carb/choke spray. Read a lot of the posts and I decided to have my carb rebuilt here in tucson. I've read the warnings about having any person do it, but this guy assured me that he's done lots of quadrajets, and I know a couple people with quadrajets who've had good experiences with him.

I checked the 107 number on the carb and wrote it down on my hand - unfortunately, I've washed my hand and don't have the carb in front of me. But the number was for a 1978 truck. Apparently the choke for that particular engine is in the intake manifold (?) and I don't have a choke. Additionally, the carburetor guy said that the ECM wiring to the ignition was nonexistent.

My options were to replace with (what I've read) an inferior aftermarket, or rebuild this carb - he's able to put an electric choke on it.

Here's the question: Will this rebuilt carb work ok for this motor (still don't know what it is) and for the crate ZZ4 or ZZ383 I'm planning on putting in if it's tuned appropriately?

I'm also planning on getting rid of the sediment in the gas tank. Should I pay $225 for him to drop/clean/reinstall it or should I just get a new one?

Thanks
John

 

[Hib Halverson]

As for the carb, it's tough to know what that carb comes from without the full number.

There is no question that the tuning of a late 70s QJ is going to be far different than the "good guy" Quadrajets of the late 60s, early 70s. While it is possible that that carb may have some significant hardware differences which could make tuning for a street high-performance application somewhat difficult, you're only choice, short of getting an older QJ, is to assume there are no significant differences other than tuning. If you initially tune the carb to run with a stock L48 which has had its electronic controls removed and are sucessful in doing so, then "retuning" for a ZZ4 or ZZ383 will be simple.

As for the choke issue, the 78 truck used a choke which relied on a bi-metalic coil mounted on the "choke stove" recess in the intake manifold. This recess was just above the exhause crossover so, as the exhaust warmed, the bi-metallic spring uncoiled and opened the choke.

I believe the 81 Corvette used an electric choke.

I would not assume that all aftermarket Quadrajet type carbs are inferior. You may be able to rebuild then retun your 78 truck emissions carb to work on what's, basically, a non-emissions sreet high performance engine. On the other hand, it may be more cost-effective to buy an Edelbrock quadrajet "clone" as they will be tuned right out of the box for a performance applcation.

As for sediment in the fuel tank, before I'd make the decision about cleaning out the existing tank or replacing it, I'd pull the tank and inspect it. If the problem is simply sediment, I'd clean and reinstall. However, if the problem is any rust and/or degradation of the tank's rubber interior coating, I'd replace the tank. In addtion, if the bladder is dissolving or there's rust/sediment, you will need to flush the rest of the fuel system.

Lastly, if the original electronic engine controls have been removed from that car and if the State of Arizona has any kind of exhaust emissions controls I/M program, depending on how Arizona's I/M program is structured, you may have a problem with registering the car with that system removed. Again, I'm not familiar with the specifics of any I/M program in Arizona, but there are states (California, Maryland, New York, etc) where removal of engine controls qualifies as tampering with emissions equipment and vehicles having emissions equipment which has been tampered with are difficult to register unless all the OE emissions controls are present and working.

 

[Voodoo81]

Hib:

Thanks for the advice. My car is registered as a classic/collectible and does not require further emissions testing in AZ.

I think I'll pursue the rebuild option with the electric choke and see what happens. I'll keep you posted.

john