sm420?


I searched, hopefully this is the right forum for my newbie question.
I have an sm420 that I ran with my 2.5L in a YJ, am now putting in a 350. I went back and got the bellhousing out of the same truck I got the 420 from. It's a 63 Chev or GMC. The bellhousing index hole is larger then the bearing retainer on the 420, I thought that can't be, must have had a 465 or something in it at one time. Well a couple of weeks ago while picking up an axle I found another 420 in an industrial rig of some sort, same larger bellhousing hole then the tranny bearing retainer.
Question is am I nuts? Can anyone else confirm what I saw, if you put the bellhousing against the tranny and push it up it seems to line up fine but I have heard clearances of .003" runout for lining all this stuff up to the crank?

Should I say fawk it and have a machine shop make up a ring to match the two, or has anyone else seen what I'm talking about?
I did do a search, and one guy is running it that way, but what I was wondering is if this is in fact the way they came from the factory?

One other question I got the forged clutch arm and the little spring clip that holds it to the pivot ball is screwed up, can you get the clip or do you have to get a whole new arm?

Thanks!

David

I run an sm420 behind my small block. I am using a swap meet bellhousing. I think it is out of an 80's passenger car. The tranny fit fine, within the .003 you stated. If I were you I would get a set of cheapo calipiers, measure the bearing retainer and find a matching bellhousing.

BTW I ran into this on a 440 w/ an A 833 tranny in my old '70 Roadrunner and just bolted it in. I never had a problem with the tranny or clutch.

what bh did u use to the 2.5l??

The BH is out of a 86 S-10 with a 2.8 V6 and a 5-speed

dmoulton: Do you still have the BH and all the Stuff for the clutch?

Originally posted by CITY WORK
The BH is out of a 86 S-10 with a 2.8 V6 and a 5-speed

wait who are you? your not dmoutlon.........
or you are just guessing cuz thats what has been done b4?

Done B4:flipoff2:

http://www.jeeptech.com/convtrans/sm420yj/

yeah thanks, know all about it already. I wanted to know what he was running, if it was something different.

Yeah, that's my junk in the link given, pretty much explains it.
My little internet claim to fame (and no I'm not the first to do it).

Nasvik has the parts, or most of them.

David

[The bellhousing index hole is larger then the bearing retainer on the 420

As long as it fits over it's OK, the bolt pattern will keep it lined up...but you have to have a sealed bearing in the front of the tranny otherwise the oil will run out on steep declines..or when upside down :)..most rebuild kits have sealed bearings that come with them.

Question is am I nuts? :rasta


One other question I got the forged clutch arm and the little spring clip that holds it to the pivot ball is screwed up, can you get the clip or do you have to get a whole new arm?

Just go to the GM dealer and tell them you have the old clutch arm for a SM420 and you want the retainer clip....it's like $2

The 420's did come from the factory with a smaller input bearing retainer diameter. I have seen the rings you can buy to align them. My 420 is bolted to an aftermarket formed steel bellhousing & block saver. The bellhousing has the larger size hole, so the trans is aligned only by the four 1/2" bellhousing bolts. For what it's worth, I have had three different engines and three different 420's in there while swapping/trying different combos, and the alignment has never been an issue or caused a problem. Always the same bellhousing.

Originally posted by dmoulton

Nasvik has the parts, or most of them.


Welcome to the Dark Side, David. :flipoff2:

Hey - do I need to think about any of this? :D

Paul

No paul, it fits your bell like a glove ;)

Thanks for all the replies!

David :vader2:

I'm using A 1980 corvette Bell on my 350/420 combo....it has the small hole, it's aluminum,it will house a 12" clutch and 168 tooth flywheel.
Napa should have your clutch parts (pivot ball and clip)hanging on the wall by the counter.