MGA MGA overdrive - that is the question

[ronzet]

Gentlemen,

Thanks for all of the sagely advice....

Bill, the disk brakes are somewhere on the 'to do' list...

I do have a new wrinkle in the transmission arena that I will post on a different thread rather than hijacking this one...

 

[billspohn]

To the original poster - as long as you swap over the rear engine plate to the MGA engine you should be fine using the B box. Don't forget about that driveshaft spacer.

Steve - as you know, you and I are in complete agreement on the utilty of using the 3 main MGB in an MGA! The 1622 bored out to MGB can get a tad dodgy on cylinder wall thickness and the crank isn't as strong as the 3 main B, although it is significantly stronger than the one used in the 1500/1600. I'm sure there must be 3 main B engines out there - for years people were tossing them away.

 

[Steve_S]

I've always been under the belief that the 1622 and 1800 blocks were nearly identical, and no difference in the cylinders themselves other than bore. Are you saying the 1622 has less metal between cylinder bores?

 

[billspohn]

I've always been under the belief that the 1622 and 1800 blocks were nearly identical, and no difference in the cylinders themselves other than bore. Are you saying the 1622 has less metal between cylinder bores?

Yes - recast block, and larger main bearing diameter.
Just as in the 1600 the cylinders were siamesed but were not in the 1500 which gave theoretically better cooling. They were pretty good at modifying the casting cores to suit the required bore size and did not specify the same wall thickness for different capacities.

Not that they were by any means using thinwall casting techniques. You can bore out 1588 to 1762 (as done on competition Twin Cams (and of course the 1798 can be hogged out to 1950 (or more, but I draw the line at 1950 as wall variances can cause serious problems)