Rebuilding my M20B25

[Driftit 1967]

Well I am about to start rebuilding my 325's motor. She has been great but the camshaft and lifters are now worn out. She has been driven the way a 325 should all its life.

But I am just wondering if there is any tips I can get when rebuilding the motor to get a few basic gains. I am not really keen on spending money on tuning and having the ecu chipped though.

I just want a strong motor that is smooth and enjoys a good track day.

Of course I will be replacing most things with brand new items and be getting the head and block checked by the pros.

I did look at going 2.7 or 2.8 but by the looks of things the ecu would need to be chipped and tuned. And the parts are hard to come by.

[BM WORLD 1265]

Well I am about to start rebuilding my 325's motor. She has been great but the camshaft and lifters are now worn out. She has been driven the way a 325 should all its life.

But I am just wondering if there is any tips I can get when rebuilding the motor to get a few basic gains. I am not really keen on spending money on tuning and having the ecu chipped though.

I just want a strong motor that is smooth and enjoys a good track day.

Of course I will be replacing most things with brand new items and be getting the head and block checked by the pros.

I did look at going 2.7 or 2.8 but by the looks of things the ecu would need to be chipped and tuned. And the parts are hard to come by.

just use a ecu from a M30B30 its close enough with a bit of playing with the spring tension in the AFM

[Jeddy 0]

Have you read this? M20B25 Rebuild

m20_head_rebuild.doc

Edited October 7, 2008 by jeddy

[Eagle 1535]

Are you just doing head rebuild or the bottom end too?. Personally Id just do the usual valve grind, port and polish and head skim and leave it at that, after all its only an M20. You could do a 272 Cam but depends on how much you want to spend.

[Driftit 1967]

Will be rebuilding bottom end too. After a few conversations with some people yesterday I think I will just rebuild the motor back to stock.

Then if I want something more powerful build up another motor.

And cheers for that head rebuild guide. Much better than the bently book which seems to focus more on the M40 motor.

[Eagle 1535]

I used the my E34 Bentley manual and that was pretty good. They don't seem to cover bottom end thou but prob figure that out easy enough when i cbf doing it . GL anyway, least its easy to work on.