dowel pin for trans on this 76 360 was missing and noticed a crack, not quite all the way through the starter side of block.

could V it out, weld and surface back of block.

its a stock re-build job for a friend, will most likely need boring.......maybe its cheaper to get another block.

Thoughts??

getting another block is a good idea, but considering where the crack is I would try to fix it. start by drilling a small hole (1/8 or 3/16) at each end of crack so it will stop spreading. grind out and fill with nickel rod or you could possibly braze it with a torch. just grind weld down flush with the block surface (check with a straight edge). just make sure weld is not sticking up. should be fine.

If it needs no machine work, it's worth a try fixing it. If it needs boring, I'd look for another block. Just my

The dowel just positions the trans, the bolts hold it secure. I'd put the dowel in and leave the thing alone. It likely cracked because some moron used a 1/2" dowel in a .496 hole. Use the correct size dowel and it will be just fine. Once the trans is bolted up there is no strain on the dowels.

Mark this day on your calendars, guys! Today I actually agree with Stanton.
The dowels are there to get the transmission centered on assembly.

Use it, no fixing required. Be sure to torque the bellhousing bolts to spec.

R.

Since the crack extends into the threads it's possible that the threaded hole will open up a little when the bolt is torqued, I'd install a Heli-coil in the threaded hole and run it.

The dowel is a critical part not only for alignment but also for torque restraint...ever see those GM one-size-fits-all thin plate adapters to swap transmissions...the dowels and two bolts are that are used for torque restraint?

Quote:

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why not use roll or spring pins

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Because they probably cost the factory more than a dowel did.

Aftermarket ... when's the last time you saw a roll pin with an offset ?!?!?

In reality, a roll pin could probably be safely used. They're spring steel so they're plenty strong. They are in a "shear" situation so could probably easily take the stress although I don't believe there is any.

If all the bolts on the trans to engine are tight, the trans is held in alignment primarily through the friction of the two mating surfaces - that friction created by the torque of the aforementioned bolts. The pins provide minimal support (if any) once the trans is bolted up.

Argue it all you want, this is my opinion and I'm sticking to it.