750/850 head interchangeability

Found an RH10 head in the wild, only have 750 cdos… can they be modified (easily I guess, anything can be made to do anything with enough elbow grease I suppose) to use on a 750 or should I just trade it down the line? Does the bore being 4mm wider on the 850 negate the premise?

Changes over the years


*The following 850 Norton Heavy Twinheads have an even wider bolt pattern than both the earlier 750 head bolt pattern or the 500-600-650 series. The C-C head stud spacing, for the holes forward from the spark plugs, has grown to 7-1/4" for all 850 heads..

RH10 is the best head, but making it fit a 750 needs some work. Best to sell it on and with the loot buy a 750 head.

kommando said:

Changes over the years

norton heavy twins heads

*The following 850 Norton Heavy Twinheads have an even wider bolt pattern than both the earlier 750 head bolt pattern or the 500-600-650 series. The C-C head stud spacing, for the holes forward from the spark plugs, has grown to 7-1/4" for all 850 heads..

RH10 is the best head, but making it fit a 750 needs some work. Best to sell it on and with the loot buy a 750 head.

Click to expand...

Good to know- thanks for the speedy reply! I’ll trade er on to my 850 guys-

When Steve Maney, and other tuners wanted to create a full race head they would often choose a good 750 head even for a 77mm (850) or 81mm (920) bore engine.

In principle it's fairly easy for a skilled machinist to relocate the 4 outer bolt holes further outward and re machine the swish band as required.

I imagine it's harder to move things inward, the principle would be the same, the harder parts would be the swish band which would require welding and then remachining.