Need Cad drawings for Cylinder head.

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jseng1

jseng1

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Does anyone have AutoCad drawings (prefer 2000 or earlier but would be happy with anything) for the Norton 750/850 cylinder head (ports & seats etc)?

I'm laying out some ports and re-angled seats for a lowered combustion chamber with longer valves and a more generous port radius to the seat. It would be a lot of help if someone sent the drawings to:

jim@jsmotorsport.com

I have the detailed drawing of the 650ss head (same valves) but not in Cad (see below).

thanks
Jim

Need Cad drawings for Cylinder head.
 
Didn't the last of the 650 models (Mercury) have the heads machined from the same castings as the Commando.
That would suggest the layout drawings were nearly the same, if not the same (?).

Not that this helps with your cad version of it.
Fullauto is possibly the only source of this - if he wants to give it away. !
And even then, could well have patterns cores etc done without any cad required...
 
Rohan said:
Didn't the last of the 650 models (Mercury) have the heads machined from the same castings as the Commando.
That would suggest the layout drawings were nearly the same, if not the same (?).

Not that this helps with your cad version of it.
Fullauto is possibly the only source of this - if he wants to give it away. !
And even then, could well have patterns cores etc done without any cad required...
Click to expand...

Yes the 650 SS etc is the same but the chamber is central and not offset as on the Atlas/Commando.
 
jseng1 said:
Rohan said:
Didn't the last of the 650 models (Mercury) have the heads machined from the same castings as the Commando.
That would suggest the layout drawings were nearly the same, if not the same (?).

Not that this helps with your cad version of it.
Fullauto is possibly the only source of this - if he wants to give it away. !
And even then, could well have patterns cores etc done without any cad required...
Click to expand...

Yes the 650 SS etc is the same but the chamber is central and not offset as on the Atlas/Commando.
Click to expand...

In what direction are the 750 combustion chambers offset?
 
Backwards = reverse desaxe.

The cam etc is at the front, so an enlarged bore can't expand in that direction.
So they went backwards.
 
I thought that when the gudgeon pin is offset in the piston. it is usually towards the rear ? Doesn't that create more leverage ?
 
Who said anything about an offset gudgeon pin in Commandos.
Thats a different kettle of fish....
 
Desaxe - "I thought that when the gudgeon pin is offset in the piston."

No - The cylinder not the gudgeon pin

https://en.wikipedia.org/wiki/Desaxe

But now I'm also confused with part of the thread above. There was a question about the combustion chamber being offset - not the cylinder.

I have seen the combustion chambers offset to the cylinder bore but are the latter Norton engines really desaxe. ie cylinder offset backward with respect to the crankshaft to get the larger bore without breaking into the pushrod tunnels ?
 
Overlay a dommie 500 head gasket with a 750 gasket, you can see where and how it was done.

The bore went from 66 mm to 68 mm to 73 mm to 77 mm. (500cc to 600cc to 750cc to 850 cc (828 cc)).
All the studs/bolts/dimensions at the front of the cylinders stayed fixed, and the enlargements all happened behind that.
Might be able to get a pic tomorrow.

The cylinder heads are a little more complicated (to measure/explain) which presumeably is why Jim is asking for the blueprints.
The valve angles and operating mechanism didn't enlarge (as much) as the cylinder did, so the offset became more pronounced.
 
Ok. Understand that.

But I guess I had assumed they had modified the cases (at least for the 750/850) to move the crankshaft back as well. - and hence the motor was not desaxe.

Looks like I was wrong
 
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