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MG MGB Technical - Rebuilding questions

Hi All

Looking at a winter project. I want to build an engine so that when my current one needs to be pulled, I can drop another in and keep her on the road. I have a 67 B GT.

Questions.

Are all MGB blocks able to mount to a D type OD trans? I know there are some differences in motor mounts, so what will work for a 67 without having to change mounts?

Are there limitations to what cranks can be used with what block? I know some talk about certain B cranks being better. Which one is recommended as the strongest?

While I plan to do most of the work myself, I don't have a unlimited budget. Not looking for a racing machine, just a solid motor.
Bruce Cunha

Bruce - "Are all MGB blocks able to mount to a D type OD trans?"

Yes, if it has the proper rear mounting plate on the block. I have a 18V engine in our 66 MGB, I just stuck the rear mounting plate from the original engine on the 18V. Cheers - Dave
David DuBois

Hi Bruce

The pre 74 cranks were forged and very strong and very heavy, these are the cranks for racing and very fast road engines. The 74 on 18v engines were fitted with a cast crank. This is around 10 lbs lighter and makes for a spirited road engine. I prefer the lighter cranks for anything but track day use type engines and above.



Peter
P Burgess

Bruce-
Only the three-synchro transmission will mount the D-type overdrive unit. The engines of the Rubber Bumper models use a different engine front plate that uses the later round motor mounts. However, the two different engine front plates can be mounted onto any B Series engine.
Stephen Strange

Ok, so it appears that any block will work Would need to change the front mounts and the rear mounting plate.

Are all cranks interchangeable for the 5 main engine?

I remember some discussion on a square journal crank that some year B had. Any great advantage to look for one?
Bruce Cunha

Hi Bruce
The flat (square) cranks are 71-74 all the five bearings are interchangeable. As I said earlier all the five bearing cranks to 74 are forged steel and pretty much bullet proof. I would prefer a later cast crank in a mild road engine.
Peter
P Burgess

Thanks Pete. Your considered one of the best, so your advice is greatly appreciated. I know your heads are considered the best around, so if you do not mind, what would be your choice for year for heads?

Guess the original question should be if you were building a fairly stock MGB engine what parts would you use? Sounds like any block is ok, crank from a 75 or later.
Bruce Cunha

Hi Bruce

The 78 on UK spec head gives very good low rpm and mid rpm power, nice and torquey, they feature a rudimentary three angle seat. They are a little stifled above 4000rpm . Have the head reconned with three angle seats, remove any sharp edges mill the head to 39ccs and you are on your way.

Peter
P Burgess

This thread was discussed between 26/10/2010 and 29/10/2010

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