Offy tripple for '70 and later head


Well-known member
I obtained an offy tripple adapter for the '70 and later heads. As I look at it I have a feeling it will not work on my '80 big log Fairmont head exactly as the instructions say. Does anyone have any experience with putting one of these on the big log heads.

Aaron Martin
How about some details on the problem. Is the shape of the offy different than the log?

It seems by the time one would machine enough material off for two flat spots on each end of the log to get the center of the offy adapter to mate to the log carb mount, one would machine all the way through the top of the log. To solve this I would just make an aluminum spacer to take up the space between the offy adapter center carb port and the center carb mount on the log. I just want to make sure I am not overlooking anything. I think the smaller log heads had a carb mount that projected higher from the log than the later large log head.
As far as I know the only mod to the intake log that is required is to match drill the end ports for the additional carbs. I've never seen the bottom surface of the offie. Dosn't it use oring?


The Offy manifold will ONLY work on the flat-topped log manifold. If you have a hexagonal log manifold, you'll never get a large enough flat surface for the o-rings to seal.

This is what your pad should look like.


This is what the manifold should look like for a 1969 "M" head and newer.


Hope this helps. Do you had the installation directions for your manifold?
I have a flat topped log, but it is the large log (1980). I am not sure how different it is from the earlier '70 and later small log heads in size. I am sure the offy unit will work but I think it may take some other modifications. I have the instructions which shows them putting it on a Maverick head.