MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB GT V8 Factory Originals Technical - 3.4 TDC?

Will the DOHC 3.4 GM fit in an MGB? I haven't seen much at all about this excellent engine, and assume it must be space considerations.

I was wondering if it is possible to fit it, perhaps under an MGC style bonnet?
Bill Spohn

Interesting question Bill. I had the opportunity to take a close look at a DOHC in the salvage yard a couple of weeks ago and it appears to be about the same height as the 3.4 pushrod engine, but a bit wider at the sides of the heads (Obviously). Steering shaft clearance might be an issue, but hood clearance shouldn't be a problem as Bill Guzmann fits the pushrod engines under the hood without problem. There might be some issues with clearance for the water pump as it looks to be side mounted. The plumbing for the upper radiator hose comes out the 'rear' of the engine instead of the 'front' as it would be mounted in a RWD chassis, but the intake should be symetrical, so might be able to reverse that.
Bill Young

Bill S,
I have considered it.... I have a new 3.4L TDC sitting in the crate in the shed.... But alas, no time. Maybe you need a TDC for a project. I dont have time to reinvent the wheel right now and that motor is somewhat of a more limited quantity, therefore, I plan to stick to my OHV 3.4L motors.

I have measured the overalls and think it could be done, but dont have the manifold to say total height. Probably need a bump in the front but boy would it scream. Doesnt the MGA allow for more room above the motor? What about your Jamacan?

-BMC.
BMC Brian McCullough

The engine is an interesting one, Brian.

It is high tech but they built it to have only moderate output because the automatic transaxles they mated it to were of limited torque capacity. Almost no after market stuff is available, but the potential is there.

If you take the engine as is, slap a turbo on it at 10 psi boost and do nothing else, you end up with about 315 BHP! If you start in and modify it for turbo, the result could be....interesting.

Unfortunately (or fortunately for my wallet), there is absolutely no way that engine would fit under the bonnet on the Jamaican!

It takes up more space and weighs more than a pushrod, but I think the payback in output in modified form would be well worth it.
Bill Spohn

Bill,
Your right. they were designed as a 275 BHP motor (or so the story goes) and continued to snap the FWD automatics of the time. I am told that by placing a set of correctly timed exhaust cams in place of the intake cams does wonders as well. This one has 210 BHP and 230 Tq in stock form. They boosted the later ones up to 215 BHP.

In the mean time this brand new 3.4L DOHC crate motor just sits in its package. Maybe the Jamaican needs a alteration to the bonnet...

How soon do you need me to get those measurements. :-)

-BMC.
BMC Brian McCullough

Hey - as this is my favourite engine of all http://www.rhodo.citymax.com/i/non-rhodo/MGA_engine_compt.jpg

and this is probably my second fave
http://www.rhodo.citymax.com/i/non-rhodo/renginejpeg.jpg

you can imagine how I'd love to use one of the TDC engines in the Jamaican - but then I'd have to change the rear axle, and I'd have this big jeezly bulge in the bonnet - I am darned sure that the height exceeds that of the Camaro pushrod.

Bill Spohn

What do you have for clearance right now and did you end up using that 3.4L SFI manifold or the Fiero manifold?

From what I see, and according to intake heights i understand, the 3.4L TDOHC is not that much taller. I dont remember exact numbers at this moment though but the intake flows a different direction and they had to get it to fit below the bonnet of the standard GM cars that were not going to have a bulge. Might be a couple of inches, but it seems like it wasn't that much. I can always measure the motor, but dont have an intake so i would have to ask some people again to measure the intake for me.

Yup, I dont think the rear axle would take this but I think you should switch to a tube type MGB rear axle anyways. Much stronger and I think it could just be bolted in.

-BMC.
BMC Brian McCullough

I used the SFI intake and I have 1/4" clearance.....

I'll see how the banjo diff holds up and switch if need be.

Of course if an MGC diff cam along I'd probably jump at it.....
Bill Spohn

This thread was discussed between 22/05/2006 and 30/05/2006

MG MGB GT V8 Factory Originals Technical index

This thread is from the archives. Join the live MG MGB GT V8 Factory Originals Technical BBS now