[NeighborsComplaint]

Since all pontiac blocks of that era were factory align-honed, wouldn’t the caps always be concentric to the crankshaft centerline and centered (within OEM tolerances) on the main cap/block saddle parting line?

[hurryinhoosier62]

Originally Posted by NeighborsComplaint

Since all pontiac blocks of that era were factory align-honed, wouldn’t the caps always be concentric to the crankshaft centerline and centered (within OEM tolerances) on the main cap/block saddle parting line?

Cite your CREDIBLE sourcing that PMD align honed all the V-8 they used. Of all the virgin Pontiac blocks I have torn down I have never seen one with crosshatch on the main saddle.

[mgarblik]

I agree. I think OE blocks were just line bored, not honed. They did a pretty darn nice job too. A production line hone operation would add allot of cost to building an OE engine. A boring, cutting operation would require much less maintenance on the assembly line. (cutter vs stones). Agree with others that just installing a random, used cap from another block, even if it looks ok with plastigage is a gamble. I think you would sleep better if it was verified with a bore gauge and fixed if needed.

[NeighborsComplaint]

Originally Posted by hurryinhoosier62

Cite your CREDIBLE sourcing that PMD align honed all the V-8 they used. Of all the virgin Pontiac blocks I have torn down I have never seen one with crosshatch on the main saddle.

Check the post right below yours.

[NeighborsComplaint]

Originally Posted by hurryinhoosier62

Cite your CREDIBLE sourcing that PMD align honed all the V-8 they used. Of all the virgin Pontiac blocks I have torn down I have never seen one with crosshatch on the main saddle.

Right here on this forum, baby. Call it align boring if you prefer.


"Pontiac V8 engine blocks from the 1960s through the 1970s were align bored at the factory as part of the casting and assembly process. This means the main journal saddles were honed to a uniform size and alignment before the caps were machined, ensuring proper deck height and main bearing fitment."
Source: forums.maxperformanceinc.com."

"Factory alignment boring was standard for most Pontiac V8 blocks during this period. The block was cast at Saginaw Metal Casting Operations and then assembled at Tonawanda Engine before delivery to Pontiac Assembly."
Source: forums.maxperformanceinc.com


"The process involved honing the main saddles to a precise diameter and ensuring they were in perfect alignment. This was done before machining the caps, so the caps could be cut flat and seated without distortion."
Source: forums.maxperformanceinc.com

"If a block arrived at the factory with misalignment or out-of-size saddles, it would be align honed (a manual honing process) to correct the issue before further machining."
Source: forums.maxperformanceinc.com