Hot Rods C4 to 351W

I'm trying to put a 1967 C4 onto a 1973 351W.
I'm finding the flex plate is to large to allow the trans to bolt on.
Is there a larger bell housing I can use or a smaller flex plate and starter to fit?
Thank you one and all for any information.

 

What tooth count do you have on the flex plate?

 

If I remember correctly there is a 157 and 164 tooth flex plate with corresponding bells

 

Sounds like you need a 157 tooth 28 oz. Imbalance flex plate. The 164 tooth is close to an inch larger in diameter.

 

The larger flex plate would be used with an AOD

 

Or C6.

 

There are 2 flavors of C4.
The small bell for 157 tooth flywheel. The bell bolts to front pump and the dipstick tube is in the case. Used on compact cars will small floor tunnels.
The big bell for 164 tooth flywheel. The bell bolt to the case with its own separate bolts. The dipstick goes to the pan. Used on full size cars and vans/trucks. Stronger bell, and usually built with more disks in the clutch pack. Less common as these vehicles usually got the FMX or C6.

It's possible to bolt a small bell to the pump of a big case/pan-fill C4. Can't put a big bell on a small C4.

There is also a rare oddball big block (429/460) pattern bell which was used behind the 351M.

The small bell held on with the pump bolts;

Also called the step case, because of the transition shape at at the bell;

The big bell mounted with 5 large bolts separate from the pump;

Called the flair case because of the shape at the bell;

 

As @RmK57 stated above, you need the smaller diameter flexplate, with proper balance to use that C4/bell.

 

Thank you. Will I need a different starter to match the smaller flex plate.

 

No, but you will need the matching sandwich plate to locate the starter correctly.