sm420 question

Will a 420 bolt up to my bellhousing w/o the use of adapters? i currentlyhave a t14 to a 225.

 

I believe it will. My business partner put one in his '70 w/225 and I'm pretty certain the only adapter was to the Model 18 T-case. I know for a fact that he didn't haveto replace the input shaft, because he didn't take apart the tranny before he put it in. If you use the adapter that utilizes the "spud shaft" you don't have to do anything to the tranny. Novak Conversions has the shortest adapter plate. They have detailed info on how to do the conversion as well.

http://www.novak-adapt.com/

 

There's two bellhousings for the T-14/225 combination. One, used in '71 had the adapter between the bellhousing and the transmission cast as part of the bellhousing. The others had a removable adapter. The ones with the removable adapter will bolt right to the SM-420, just remove the adapter. Correct depth, indexing hole, etc. If yours is the cast in version then you need the earlier bellhousing without the adapter. Follow Posimoto's link to Novak's web site. TONS of good info on there. Nickmil

 

The T86 is the one that has the spacer cast into the bellhousing, right? If tht's the case the others have the removable spacer with the standard GM bolt pattern underneath, IIRC........

 

No the T-14 (see above post) although a T-86 could be bolted to the one with the cast in adapter. T-14 was standard in '71 behind the V-6 and '71 was the year they used the one piece adapter and bellhousing. Nickmil

 

I just took the 86 out of my commando and it has the seperate adaptor forsure.

Sm 420 bolted right up except for a very small clearance issue between the top of trans and bellhousing.
You just grind their a bit you will see when its going together.

I ground the bell but would do the tranny instead if I did it again.

 

my bell has no adapter that goes between the trans and the bell. no cast in adapter that i know of. the trans just mounts to the bell which is just like a standard bell nothing extra here. so do i need anything?

 

.You wont be able to see the piece cast into the bell if there was a t-14 bolted to it with no cast iron adapter it is not going to work.

 

so i have to find another bellhousing?

 

Yes.

 

what years will work?

 

I'm probably missing something here. On my 70 that had the t14 I was able to use the bell but it did require drilling out two holes to mate to the sm420. It's the original, one pc bell housing.

Maybe the 71 is different? I'm just not following this.

 

The '71 bellhousing had the adapter between the transmission and the bellhousing cast as part of the bellhousing which makes it too long for the SM-420 and most other transmissions as well. Your '70 should have had a removable adapter between the T-14 and bellhousing. In fact it had to have again because the T-14 Input shaft and front bearing retainer are too long to just use a normal stock style Buick V-6 Bellhousing.

Regarding which bell to look for, any '70 and older CJ V-6 bellhousing will work as well as many Buick Car bellhousings. Watch out for where the release arm comes out of the bellhousing as the angle/location is different on some cars and if it has a starter pocket on both sides to fit BOPC, then the driver's starter pocket can interfere with stock Ross style steering. Nickmil

 

Here is a 71 model bellhousing with a t14 behind it. Notice there is no adapter for the trans. The adapter is cast into the bellhousing.