C2 - Clutch Identification Help

[Rory Riedy]

All,

Am a little confused, restoring a '68 427/390. Car was originally an automatic but converted some time ago by individuals unknown with a Muncie M-20 4 speed. Current set up is this:

Flywheel casting is #3781021, marked GM 3, B274, it measures 12 1/2" across the plate & has a 153 teeth ring gear

Bellhousing casting is #3340383, marked GM

Clutch plate & pressure plate have no markings but measures 10 1/2" across the face, with 10 spline.

Would like to get a new clutch kit from AC Delco but when I go to their site it says I need kit #381258. This kit is set up for an 11" clutch. What kit or parts do I need?

Most everything I read says that the setup I described above is for a SB setup or an L88. However I have read a few articles that says some other BB were setup with a 10 1/2" clutch.

What do the experts have to say?

Thanks a million as usual.

Triple R

[Mike McKown]

Re: C2 - Clutch Identification Help

Get a 10 1/2" clutch for a C-2. No reason it won't work well. I don't know what all those numbers you threw out mean but it's seems they are currently compatiable with the smaller clutch. Bigger is not necessarily better in this case.

If you want the larger clutch you have to change flywheel, bellhousing and starter nose and starter brace. Check to make sure if you do, in fact have the starter brace at the front of the starter to block.

[Joe Lucia (12484)]

Re: C2 - Clutch Identification Help

Rory-----

All Corvette big blocks originally used a 14" flywheel and 11" clutch EXCEPT:

1) 1965 L-78

2) 1967-69 L-88

If you want original configuration, then you'll need to change to the 14" flywheel and 11" clutch. This means changing flywheel, pressure plate, friction disc, bellhousing, and starter.

If you are not concerned with original configuration, you can just keep the 12-2/4" flywheel/10-1/2" clutch set-up you have.

While 67-69 L-88 used a special, HD friction disc, the 1965 L-78 used, basically, the same clutch set-up as 63-68 small block. So, just select the clutch for a 1968 small block (NOT a 1969 or later small block, though)and you'll have what you need. If a 65 L-78 can use the 10-1/2" clutch, a 1968 L-36 won't have any problem with it.

Do I recommend this clutch set-up for a 1968 L-36? No, I don't. However, it will work ok and it will save you a lot of part changing at this point.