quick clutch size question: is a 70 350 11 inches?

Some background: I'm retrofitting a 71 Buick 350 engine from a 71 Skylark into my 64 Special. I'm also converting the 64 Special to a manual 4 speed. So, I purchased a flywheel from NAPA for a 71 Skylark with a 350. I also purchased the clutch kit for 71 Skylark with 350 BUT kit has the fine-spline clutch. I'm retrofitting a coarse-spline Saginaw 4 speed. So I returned the 71 clutch kit and thought I was smart to order a 68 Skylark 6 cylinder 3 speed clutch kit because that would assure the coarse spline clutch. It was, but I think the 68 parts are a 10.5" clutch, while my flywheel is an 11" clutch (the 68 pressure plate mounting holes' bolt circle was too small for my 71 flywheel).

Just want to see/confirm that if I instead order the clutch kit for a 1970 Skylark with a 350 I'll get the coarse spline clutch and the proper 11" clutch size (sorry but I don't recall if the NAPA had the details of the clutch diameter on their computers). So I'd like to know if my plan would work.

Nothing fancy or high power with my car it's only a stock skylark 4 barrel motor so I'm not looking for Centerforce or other stronger aftermarket parts.

Thanks for any help.

 

I just measured the 68 clutch and pressure plate: they are 10.5 inches. The flywheel mounting bolt circle for the 6 bolts is considerably bigger. I checked my NAPA receipt and it says 1971 Buick Skylark 5.7L
part# BK_600-5151

Only thing I can think of is that maybe in 1971 when GM converted all manual transmissions to the fine spline input and output shafts, they also converted all V8's(small and big) to the 11 inch clutch size.

 

Thanks I'll see what my flywheel measures. Now I'm considering returning my 11" flywheel, because I've already buggered up my pilot bushing which came with the clutch kit (includes clutch disk, pressure plate, throw out bearing, and pilot bushing) and I'd feel bad returning that. Last night I tried out the bronze pilot bushing, and after some strong hammer blows I stopped myself (been reading all the threads regarding this). I was only able to insert it about .23 inches then took it out and said "lets change plans". My 71 Skylark 350 crank is drilled for the bushing, but I think the bushing itself is a little oversized on O.D. as we know. The NAPA bushing does not attract a magnet (good news) and it does slip over my Saginaw input shaft smoothly. Here's how the NAPA bushing measures out of the box:

O.D. 1.0965 inches
I.D. .589 inches
length: .756

I plan to clean up the hole in the crank just to knock off the surface rust, then measure it, and then establish a target O.D. on my bushing to be about 0.0005" smaller then that. Then I'll have my bushing turned down.

I'll talk to NAPA today to see if a 1970 Skylark 350 flywheel is 10.5" or 11". I'll probably swap flywheels I'm thinking.

 

I was under the impression that all small-block bucks were 10.4" (or 10.5" depending on who's measuring) except the early 70's 350 Jeep, which was 11" . My '70 350 was 10.4" .

 

Thanks Scott.

UPDATE: I worked with the store manager of my NAPA (very helpful guy) and we walked thru the issue. Turns out he had a new paper catalog from their new flywheel supplier, and when we found the correct 10.5" flywheel part number in that paper catalog and plugged it into the NAPA computer, low and behold there it was, the correct flywheel. Obviously the computer system needs to be updated. I'll know more later today when I do my exchange as far as part numbers. Cost I think was still around $220.00 for the flywheel. I explained how I wanted to buy a separate pilot bushing since I had buggered-up the one that came with my clutch kit (from hammering on it and scratching the I.D. while removing it). I mentioned how I will need to turn the O.D. to fit the Buick crank and he said he wanted to get to the reason why his part won't fit out of the package properly, so we'll see if we can make any headway with that too.

 

[HR][/HR]sad to report none of Napa's suppliers provide this flywheel. Even the books listed the chevrolet style part number. Next question : are the Buick pressure plates and clutch disk unique also? Or will my chevrolet parts work?

 

Yeah I was thinking to myself I've never heard of a mainstream vendor supplying an off-the-shelf flywheel for a 350 or 455.

The answer to your question is: clutches are not Buick-specific. Almost any clutch made for a GM application will work.

 

Good news, thanks Scott. Yeah, the ironic thing is that I originally went into the NAPA looking ONLY for a pilot bushing, and when the store person said "looks like we have the flywheel for that model too...." and I said Really?? Well how much? Then the ball got rolling....but turns out they over-reached and assumed the same Chevrolet parts interchange with the Buick parts.

 

I bought a SBB flywheel and it has the hole pattern for the 11" clutch also, and I think the wheel is OEM. So Buick must have used an 11" at some point with the small blocks. Anybody have a clue what year that was and what model?

Jim

 

Yes. Used on Jeeps (Grand Wagoneer? )in the early 70s with the 350 SBB. That is a HEAVY flywheel though, like 50 lbs vs the stock 35 lbs

 

So, it would take longer to spin up but it wouldn't bog down. Just what a Jeep needed.

 

The pilot bearing will give you some trouble i think.

 

Why so? You talking Jeep or Buick in general?

 

Buick, not the same as the rest size wise

 

I know Chevy is different but I was under the impression that B-O-P were all the same. My info is based on this chart from AutoGear.

http://www.autogear.net/wp-content/uploads/2015/03/pilot_bushing_chart.pdf

 

The crank may or may not be the proper size and depth. As in the notes below #4

 

That is only listed for the extended pilot bushings, not the standard one.