[Jack Gifford]

Working on re-hashing my four cylinder hemi Pontiac as a two-cylinder, after severe detonation destroyed cylinder #2. Main web #2 of the aluminum block got beat up and needed cracks TIG welded, so #2 main bore ended up out-of-round. #1 & #3 bores are okay, so I employed my pseudo-align-bore contraption to make #2 round again at .030" over, so I'll use .015" brass shim stock behind the bearing insert (the #2 main cap survived without distortion).

[steve25]

Jack I think the plasticity of Brass will not stand up to the loading .

Maybe if there big enough so they can be cut down how about two .015" feeler gauges?

[PAUL K]

Looks good Jack. Where there's a will, there's a way.

[hurryinhoosier62]

Originally Posted by Jack Gifford

Working on re-hashing my four cylinder hemi Pontiac as a two-cylinder, after severe detonation destroyed cylinder #2. Main web #2 of the aluminum block got beat up and needed cracks TIG welded, so #2 main bore ended up out-of-round. #1 & #3 bores are okay, so I employed my pseudo-align-bore contraption to make #2 round again at .030" over, so I'll use .015" brass shim stock behind the bearing insert (the #2 main cap survived without distortion).

Jack, this should work. What is the diameter of the cutter bar? The only foreseeable problem I can think of is chatter and possibly “swag” in the cutter bar.

[Jack Gifford]

The mandrel is 3/4" diameter chrome moly and does not flex. It's a precise fit in the carrier blocks- would bind if not well lubed. With such a short tool bit, no chatter cutting cast aluminum up to .004" deep- I usually only cut about .001" deep, rotating the feed screw very slowly by hand.

[hurryinhoosier62]

Originally Posted by Jack Gifford

The mandrel is 3/4" diameter chrome moly and does not flex. It's a precise fit in the carrier blocks- would bind if not well lubed. With such a short tool bit, no chatter cutting cast aluminum up to .004" deep- I usually only cut about .001" deep, rotating the feed screw very slowly by hand.

Thanks, Jack. I’m used to using a Berco BC-5 align boring machine with three different cutting bars and tool holders. Even with short bits ( carbide) and reduced feed speed (.5 inch per 100 rpm) we still had chattering problems using the 55mm bar ( roughly 1.5 inches).

[Stan Weiss]

Originally Posted by hurryinhoosier62

Thanks, Jack. I’m used to using a Berco BC-5 align boring machine with three different cutting bars and tool holders. Even with short bits ( carbide) and reduced feed speed (.5 inch per 100 rpm) we still had chattering problems using the 55mm bar ( roughly 1.5 inches).

55mm is just a little more than 2.165"

Stan