Question: Clutch & Flywheel Size for 1969 427/390?

[fine69]

Hi Everybody,

It's been a while since I've posted - busy life.

So here's my question: What size clutch, flywheel, and damper do I need for a 427/390? I see there are 10.4" and 11" clutches.

I pulled the 350 out of the Vette and installed it in the Camaro. Since I blew 2nd gear in the transmission, I went ahead and also kept the Muncie attached (for now, anyway).

I plan to re-use the bellhousing that came with the original Corvette 350.

I have the 427 back from the machine shop; magnafluxed; it had to be bored +.040 and aligned. I have it home for painting. The next step is to return it to the shop for balancing. I believe they will need the entire rotating assembly - including the torsion damper, flywheel with the clutch pressure plate attached.

Any info is appreciated!

Thank you.

Ralph

 

[JohnZ]

So here's my question: What size clutch, flywheel, and damper do I need for a 427/390? I see there are 10.4" and 11" clutches.

I plan to re-use the bellhousing that came with the original Corvette 350.

The '69 427/390 used a 168-tooth flywheel and 11" clutch, and a 7"-diameter harmonic damper (solid-lifter cars used the 8" damper).

The '69 350 also used a 168-tooth flywheel and 11" clutch, and a 621 bellhousing that will work with either engine.

 

[fine69]

The '69 427/390 used a 168-tooth flywheel and 11" clutch, and a 7"-diameter harmonic damper (solid-lifter cars used the 8" damper).

The '69 350 also used a 168-tooth flywheel and 11" clutch, and a 621 bellhousing that will work with either engine.

John,

Thank you - very helpful info as always! I can now order a new clutch. Since I'm going pretty much stock with the rebuild, I'm ordering a Sachs as I understand they're pretty good.

Progress has been slow... but had a perfect evening.... got home painted the final coat on the engine/heads/pan w/an HVLP gun... great weather, so no bugs to screw up the finish... and now CAPS HOCKEY!

Thanks again John!

Ralph

 

[orlandjoe]

My expirience with a 454 and the 11 inch clutch required the bigger bellhousing which has a bulge around the starter opening. The 10.4 inch clutch is ok for the 350 bellhousing which has a straight line down the starter side. So I guess I'm saying the 10.4 is ok for the 427 with the 350 bellhosing.

 

[JohnZ]

My expirience with a 454 and the 11 inch clutch required the bigger bellhousing which has a bulge around the starter opening. The 10.4 inch clutch is ok for the 350 bellhousing which has a straight line down the starter side. So I guess I'm saying the 10.4 is ok for the 427 with the 350 bellhosing.

The last Corvette that used the small "403" bellhousing, 153-tooth flywheel and 10.5" clutch was the '68 327 small-block (except for L-88's and '70-'72 ZR-1 and ZR-2). All big-block Corvettes (except L-88/ZR-2) and all small-blocks from '69-up used the "big" 621 bellhousing with a 168-tooth flywheel and 11" clutch.