Flywheel

[3macs1]

Even if it did fit. What would the starter snout look like. You would be lucky to get the busHing in not much more.

[BARN FIND]

[ QUOTE ]
The "621" measures 16 3/4" and the "403" is 16 1/4" That 1/2" is why the 11" flywheel will work only in the 621 & 444 bellhousing. Kim

[/ QUOTE ]

OK...I spoke too soon saying it would fit, the flywheel #3791021 is a 153 tooth wheel and is a smaller diameter than the 168 tooth wheels which came with both 10.5 and 11 inch PP's. Which BH does the L78 that started this post have?

[firstgenaddict]

The starter snout for the smaller beelhousing has the straight across bolt pattern like a Monza with a V8 or the 67-69 Z28.
The snout for the larger flywheel has the staggered pattern... we just went through this with the Black 69 Rs/Z when we put the motor back in with the stock sized flywheel in it

[YENKO DEUCE REGISTRY]

What I want to do is put a 10.5" setup on a BB with a 403 BH. I thought the starter opening in the BH was the same size?

[3macs1]

Hi Marlin:
I for one would not use a 10 1/2 inch clutch behind a l-78 but everyone has their own way of doing things.Those doing it with no problems please chime in.I guess I just like my feet too much and would worry maybe not justified with a 10.5 taking on all of that HP, but that is me.
Here is the differences in the openings for the starter.
621

403



I agree with james on the starter snouts but remember the 403 using a very small end cast iron snout with the cross bolt pattern which is not common.Might be with you z-28 boys but I had a hell of a time finding one when I used this combo on a 292 chevy.
Hope the pictures help.

[YENKO DEUCE REGISTRY]

I thought the L88 'vettes used a 10.5" setup?

[L78steve]

I believe you can use the 10.5/403 set-up on the big block.But the problem will be a shorter clutch life.I used a 10.5 on a torquey 350 and went through clutches rather quickley.I then changed to a 11" set up and it solved that problem.

[Kim_Howie]

I Think the ZL-1 also used the 403

[3macs1]

[ QUOTE ]
I thought the L88 'vettes used a 10.5" setup?

[/ QUOTE ]

The one I have out of a 69 L-88 is a 621 11". There may have been some applications for the 403 with a BBC in 65/66 but I remember 99% of 403's being installed with small blocks vetts and z-28 and the BBC getting the 621's.

[YENKO DEUCE REGISTRY]

Can someone decode this part # for me? 3791021 I'm told it's a 10.5" flywheel applicable for a #403 bellhousing.....