750 Crankcase Deck Height?

[TJBaker57]

Try as I might I have not been able to find any published dimension for the factory height of the crankcase deck where the cylinders mate up.

In other words how would one determine, by measurements, if a set of crankcase halves had been previously machined, altering the height of the deck?

Thought I may have found a good source in a post on October 14 2025 in this thread below. But I cannot pin down the deck height in what looks to be a factory blueprint.

Camshaft & Crankshaft Centerline Dimensions Relative to Case Deck | Norton Owners Club

www.nortonownersclub.org

 

[mdt-son]

I recollect someone asking the very same question a while back. Was it you?

Why don't you have your cases measured by CMM? One pivotal question is, how di you set a plane of reference?

- Knut

 

[TJBaker57]

I recollect someone asking the very same question a while back. Was it you?

Why don't you have your cases measured by CMM? One pivotal question is, how di you set a plane of reference?

- Knut

Nope, Not me, or at least I don't remember doing so !!

The fellow in the referenced thread used references of the camshaft and crankshaft centers. But he wasn't looking for deck height. Though he was preparing to skim the deck.

The drawing someone there sent to him gave him what he needed.

 

[Dedubyah]

If you were to assemble it, wouldn't the deck height of the pistons in the barrels give you a good idea?

 

[TJBaker57]

If you were to assemble it, wouldn't the deck height of the pistons in the barrels give you a good idea?

Perhaps it would, if you can be absolutely certain nobody had machined/altered the barrels.

 

[Fast Eddie]

Perhaps it would, if you can be absolutely certain nobody had machined/altered the barrels.

It’s very easy to measure the barrel height to confirm that.

Seeing as the actual importance of deck height is the piston position, I’d suggest assembling and measuring to be the best method, especially in the absence of specific data points to check against and a CMM to check them with.