Adapting a Later Bell to an Earlier Block?

[SoCar72]

So, the bolt pattern changed from the early 4-main blocks into the later 7-main blocks. As I understand, both share the same lower bolt bosses, but the uppers moved, with the dual pattern being the cross-over for a few years. The bells and flywheels grew with the change, but didn't share the dual pattern, only using one or the other.

Has anyone ever adapted a larger bell to a smaller block?

I read an old post of a guy who adapted a SBF blow-proof to his L6 with a custom built block plate/motor mount plate.

Considering that the large and small bells share a couple bolting points, would it stand to reason that a custom block plate could adapt the two? Perhaps the plate flathead bolts to the block with studs attached for the upper bell holes. The plate would likely need to be thicker than stock for bolting and rigidity compensation, which may require shimming the flywheel and drawing special attention to the starter mount to compensate for offset.

Any thoughts or heckles?

 

[aribert]

I would caution against "shimming" a flywheel. Flywheels are piloted to the crank. A flywheel has a tremendous ammount of mass that is just waiting to maim your legs/feet where it to let go and punch thru the floorpan. You would be much better off with a conversion plate AFTER the bellhousing.

 

[SoCar72]

That is a very good point. The cast aluminum bell would only slow an exploding flywheel-clutch assembly should it come apart. A pro drag racer back in the day lost his feet due to such an explosion, back when the drivers rode over the rear axle.

With such an adapter, the intent would be to keep the offset to an extreme minimum with the hopes of avoiding a shim. Though I wouldn't expect the shim more than maybe an 1/8". If an adapter is needed behind the bell, such as a T-5 conversion, perhaps thickness could be subtracted to help maintain an acceptable pilot depth without adversely affecting the clutch disc spline engagement and release bearing travel.

Thank you for the input.

 

[65andonly18]

Ive wandering about this as well, modern drivelines sounds like it has a kit that works for 65's which would be the earlier block. If there is any other way or place i would love to see one.