pre 70' 390 head bolt (options)

[Eazybee]

Is there any reason why you can't drill and tap the 7/16" bolt holes in a 69 or earlier AMC v8 block to fit the 70' and later 1/2" headbolts?

I've seen other options, like a bushing or shim to resize the holes in the heads to fit the smaller 7/16" bolts, but that doesn't resolve the potential problem of the weaker head bolt in a higher HP engine.

Anyone have any experience with this?

Thanks.

[jeepsr4ever]

The reason is tha bold head landing becomes to small and to reshape it requires a accurate setup. Also you may not have the right amount of material for the stresses of the torque when heated up to operating temp.

[tufcj]

I just built my 69 390 with 70 dogleg heads. I used 7/16" ARP head studs in all the holes except the 3 under the exhaust ports where I used ARP bolts (clearance probs with my headers). I also used the stepped dowels (just at the 2 corners to position the heads, no need to shim all the holes). I think it's plenty strong for the 10:1 compression, 450+ HP engine that I've built.

Bob.
tufcj

[Eazybee]

Thanks guys!