Rh10 head differences

Status
Not open for further replies.
D

Dkt26

Joined
Jan 17, 2012
Messages
521
Country flag
Found an rh10 head for sale yesterday that had been recoed by Kelly cork. Kelly is probably one of the most notable norton guys on the east coast of Australia so I imagine the head is in primo condition. Anyway, moving on. The guy said it was a mkiii head. They guy selling it that is. He is a Vincent man with a couple of vinnies and a norvin. Bastard!!!!
My question is do the mkiii bolt patterns and head differ from the earlier 850's?
 
According to Phil Yates the Mk3 went back to the RH4 head.
All the 850 heads interchange I thought, different port diameter / compression ratio only.
 
Haha!! Well played sir!
I don't really know a hell of a lot bout mkiii and any real differences except crankcase strengthening and shorter crank plus the put everything on the other side, oh and he electric leg!!
I asked the guy about the rh10 head head had and he looked at me like I was an alien. He said he had a mkiii norton head only.
Thought I would mention that I came across one anyway as they seem to be the desired option for most folk wanton to do some port work. This one has polished ports and to the eye, looks to be in good condition.
 
Dkt26 said:
Found an rh10 head for sale yesterday that had been recoed by Kelly cork. Kelly is probably one of the most notable norton guys on the east coast of Australia so I imagine the head is in primo condition. Anyway, moving on. The guy said it was a mkiii head. They guy selling it that is. He is a Vincent man with a couple of vinnies and a norvin. Bastard!!!!
My question is do the mkiii bolt patterns and head differ from the earlier 850's?
Click to expand...

MKIII had RH 4 head I think. If Kelly says its RH10, it's RH10 which, like the RH4, will fit any 850.
 
Dkt26 said:
Time Warp said:
To date I have had no luck finding a working contact number for Kelly Cork to look at my RH10.

This suggests all 850 heads interchange.

http://www.nortonownersclub.org/support ... tification
Click to expand...

Kelly Cork - Machining/Engineering, 7 Cedar St. Maleny. 07 5494 2648(BH)
Click to expand...

Thanks, that is the number I have tried a few times but it goes to a automatic response from Telstra.
I will try it again tomorrow, bad form to phone on a Sunday.
 
Kelly isn't selling the head. A Vincent guy is so that is where the confusion sets in however Kelly did the work on the head.
I know a few up his way so may be able to get a different number if that one doesn't work out.
I spoke to him bout 18months ago. He is a mad keen miso so he may have hit the road for a while!!
Let me know how you go and if you don't have any luck I will follow up for ya.
Maleny is only an hr or two away, dependent on the route you take!!
 
Recall reading somewhere the rh4 were more prone to cracking. Why would that be?
 
htown16 said:
Recall reading somewhere the rh4 were more prone to cracking. Why would that be?
Click to expand...

I have a RH4 head and it cracked right between the intake port to the center of the head.
When I had it on the bike it would overheat and idle bad.
I sprayed some carb cleaner to look for leaks and found the crack.
I showed up because dirt would build up in the crack and make it visible.
I still have the head. I wish it could be fixed but I don't know how that would be done.
 
htown16 said:
Recall reading somewhere the rh4 were more prone to cracking. Why would that be?
Click to expand...

1. The 850 heads have a 3/4" guide therefore a larger diameter hole than 1/2" 750. The 750 combat 32mm port has precious little head aluminum holding in the guide. With a larger 850 guide there is even less head/guide thickness on the inlet side of a 32mm RH4 then a combat 750 which tend to not be cracked.
2. An RH10 has smaller 30mm ports therefore 1mm more aluminum to hold the guide, and.... resist cracking when the gorilla at the factory sledge hammered in the guide and cracked the RH4 heads before it was even installed on the new engine. I very strongly feel this was a factory induced problem that went undetected. There are way to many cracked RH4 heads with almost zero miles to be a use problem IMO...

http://atlanticgreen.com/nhth.htm
 
dynodave said:
htown16 said:
Recall reading somewhere the rh4 were more prone to cracking. Why would that be?
Click to expand...

1. The 850 heads have a 3/4" guide therefore a larger diameter hole than 1/2" 750. The 750 combat 32mm port has precious little head aluminum holding in the guide. With a larger 850 guide there is even less head/guide thickness on the inlet side of a 32mm RH4 then a combat 750 which tend to not be cracked.
2. An RH10 has smaller 30mm ports therefore 1mm more aluminum to hold the guide, and.... resist cracking when the gorilla at the factory sledge hammered in the guide and cracked the RH4 heads before it was even installed on the new engine. I very strongly feel this was a factory induced problem that went undetected. There are way to many cracked RH4 heads with almost zero miles to be a use problem IMO...

http://atlanticgreen.com/nhth.htm
Click to expand...
True that!!
My rh4 is good however there was also issues with porosity in the casting or do I've heard.
Mine was a lucky one I think!!
I am changing it to the fullauto as my exhaust port threads are knackered. I will get them repaired properly down the track but as my wife is, well, friggin amazing she sprung for the FA for my 40th birthday.
I will keep the rh4 in the event that I build a FB framed commando or something similar. That way the rh4 can go back on my original commando
 
If you are changing from a good RH4 to a Fullauto and making no other performance mods, it will be interesting to see what the result is.

Glen
 
worntorn said:
If you are changing from a good RH4 to a Fullauto and making no other performance mods, it will be interesting to see what the result is.

Glen
Click to expand...
I absolutely agree glen. Should be very interesting.
I use standard cam, stock hepolites (20thou over) and the rh4 is rebuilt but again stock standard.
If I could afford to dyno it I would to get an actual comparison. Unfortunately I will need to do a handlebar/butt on seat sliding comparison!!!
 
Its been said most anyone can tell 10% improvement in power but not so many can tell just 5% improvement unless competing with self or others. Get a G-force type gizmo to put on bar then can do time to distance comparisons to get a sense of the new head expense.
 
Time Warp said:
According to Phil Yates the Mk3 went back to the RH4 head.
All the 850 heads interchange I thought, different port diameter / compression ratio only.
Click to expand...

The NOC link you have provided indicates there was no 1975 Commando. I might be getting a bit paranoid but I feel a serious case is being built up against MkIII owners. And I have no doubts about who is behind it.

Phil
 
The "case" had already been built Phil.
By you mate and it ain't got nothin to do with any sort of norton ever made.
Humility and in your case abstinence is the key to survival
 
Rh10 head differences


Well, that's another head ruined!
 
Status
Not open for further replies.

Similar threads

oldbeezer
  • Locked
RH10 head mod question
Replies
2
Views
1,284
oldbeezer
oldbeezer
A
  • Locked
Refitting rockers on RH10 head
Replies
2
Views
776
comnoz
comnoz
htown16
  • Locked
750 vs 850 head differences
Replies
4
Views
1,824
lcrken
lcrken
W
  • Locked
rh10 head
2
Replies
25
Views
5,399
Dances with Shrapnel
Dances with Shrapnel
M
  • Locked
RH10 head removal - modified open-end wrench?
Replies
2
Views
971
L.A.B.
L.A.B.
Back
Top