Mercruiser 3.7 Build, 1970 Cj5? Part 2, Fab And Adapting!

Open header!

 

Replaced power valve in carb with a new one for a slight imrovement.
After searching many post on carb, I decided to drill 2 1/8 holes in butterfly,
Big improvement, plugs starting to grey not blk. About all I can do until install in spring.

 

I got about 2hrs on the desktop with the boys asleep and a binder of part drawings printed and some readings off of Novak and advance adapters web sites. That said it looks like the crank sits 1" further from the Transmission than a gen 1 sbc. Can you get a measurement from the bellhousing to block mating surface to the end of the crank where the pilot bushing sits flush to and can you show a picture of this being measured. I think this is .25" into the block. On a sbc I am finding the crank extends past the bellhousing mounting surface by .75"

 

From the deepest part of the pilot hole.

6-7/8

 

From the crank flange face where flywheel bolts.

almost 6-1/4

 

6-1/4 crank flange face.

Thanks a bunch for your help!

 

Need more pics, or questions, just let me know?

 

Those pics actually flywheel, not crank face.

 

Ok for that dimension I got 5-1/8 on my 85 4.3 now this is the only year 4.3 with a 2 PC rear main like the pre 86 350s so this might not be an ideal comparison.
This is taken with the ruler on the same surface of the flywheel and the edge against the bellhousing index hole. It's just a lot tougher to measure since my engine is in the jeep and my Transmissions are on the bench.

Sm465 and t90 by Joe with a jeep, on Flickr

I have a lot of pics loaded and will be sorting them into short T-90a, T90j, and sm465. I have to look at the bearing retainers to tell.

I haven't gotten a good drawing on the PC finished but I can say to run the t-90c you will need to turn a index ring to go from the 5.125"index of the bellhousing to the nose of the t-90c (I didn't think to measure that when I was out there)
Without a spacer or adapter there around .25" more room for your pilot bushing plus the difference from flywheel to pilot bushing between my 4.3 and the mercruiser.
Then there is the clutch... With the t90c indexed into the Chevy bellhousing both release arm balls are available to use. But nothing is cut and dry to bolt in. Best option I see is to have a throwout bearing holder turned that will space the Chevy release bearing forward (roughly 1") and centered on the t-90c nose.

If this direction sounds good it would require a machine shop to make the pilot bushing that is longer than normal with a shoulder. The release bearing holder and the indexing ring.