Hold down clamp

[Tom Goldman]

The MSD 7905 hold down clamp is the strongest Chevy type clamp I've found.
It's made for holding magneto's which are notoriously difficult to keep from moving.
I used to silicone the base gasket, but I've since machined an O-ring groove in the collar and it works great, no vacuume leaks and it's a lot easier to phase the distributer.