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MG MGB GT V8 Factory Originals Technical - GM V6 into a '77

I'm planning the installation of a GM V-6 into a sturdy 1977 MGB. I would like to use the 3.4L but with carburetion rather than fuel injection.

Can this be done?

Should I get 2.8L heads and will they bolt onto the 3.4?

Chuck Edwards
Charles Edwards

Chris, check out Bill Guzman's web site. He has the GM 60 degree V6 down to an art.
Bill Young

We have a GM 3.4 crate engine in our MGA. It is intended to swap into early S10's so it has the cast iron heads for the carb route. It works very well.
James Wiebe

For general information.
The cast iron head 60 degree V6 comes in 2.8, 3.1, 3.4
all blocks are the same as well as the heads.
The diference is in the bore and stroke.
The manifold to use is the Edelbrock manifold which is listed under the Jeep section.
This manifold is a two piece, the botton piece and the top where the carb bolt to it. The top paret is cut down 2 inches or buy ine of the CNC top sections from Garret or from CCE this is needed to fit everything under the hood. A 1/2 inch phelonic spacer is added to keep the carb cool.
The exhaust manifolds from the swap kit flow very nicely, thus requiring the carb to be rejeted. The carb to use is the Holley list #8007 390 cfm This carb comes with 51 or 52 jets and it's calibrated for the samll V8 As mention the exhaust flows very nicely and the jets have to be change from 51 or 52 to a 58-59 on the 2.8 and 3.1 60-62 on the 3.4 This are only a starting point, the V6 like lots of advance timing.
A 3.4 with a recalibrated carb and the correct timing it will develop 200 + hp and over 200 lb of torque, this is on a crate engine that comes with a factory performance cam (crane specs) The secondary vacuum spring must be tune to work properly. Trial and error or dyno time is require, a good starting point is the a yellow spring or the stock one which is silver.
Bill Guzman

Hi Charles,
Heads- all cast iron heads are the same for intake/exhaust. At some point, the 2.8 received a larger valve upgrade.

There are several styles of fuel injection and even more carb versions.

Stock S10 2 barrel manifold with stock carb or change the carb out for a weber unit.

There was also years ago a 4 barrel made by Offenhauser if i remember correctly, but these are hard to find.

Then there is the easy to find 4 barrel two piece high rise Edelbrock manifold that you can stick a 390 cfm on with good results.

I have even heard of some guys producing variations of these as well.

A carbed motor should use a distributor from a 1982-1985 S10, Camaro, Firebird, Jeep Cherokee, or some of the FWD GM 2.8L V6 cars from 1980-1985- make sure to get the coil and wires between the two to save a few dollars later.

If you get a crate motor, plan to also get a "core" motor for the starter, alternator, pullies and so on.

You will need a flywheel, there are several that work, but usually most people use what came with the motor- pending it was a manual...

HTOB (hydraulic throw out bearing) we sell a good unit that fits any GM T5 and have sold lots of them- our own kit that we have our own instructions and hardware since the supplier still produces the wrong hardware and incomplete instructions.

Gearbox- I recommend a V6 Camaro T5. You will not be happy with 1st gear and the overdrive will not be as 'good as it could be', but the Camaro V8 T5 still has poor ratios when you consider where 4th gear is in the overall picture and where the power come on in the V6 and the torque is so wide of a band. By recommending this, i am saying that you will save money now and be able to upgrade to a better rear axle sometime in the future. You will probably still be ok with the system as is..

If you never plan to upgrade the rear axle, then spend the extra money and get the V8 T5.

Basically, for a V6, you do not need the close ratio gearbox (V8 T5), and it is not as good a system unless you are building a high and peaky torque motor- porting heads, over 10.0 to 1 and so on.

Driveshaft- there are alot of companies that fabricate this. We do it, but any driveshaft/ u joint specialist can do it.

Suspension- nothing needed. You drop a few pounds. You will probably find that the late model car with how high it stands is FAR better to be lowered down for a lower centre of gravity.

Brakes? We dont need no.... You only need to upgrade if you are going to drive harder. Just make sure your stock brakes are working Properly.

Hope that gives an idea of other things to look for..
BMC Brian McCullough


Thank you. That's a lot of great information.
Charles Edwards

This thread was discussed between 26/08/2005 and 29/08/2005

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