'71 Commando Cylinder Head Casting
- Thread starter wot
- Start date
- Status
SteveBorland
VIP MEMBER
- Joined
- Nov 15, 2010
- Messages
- 782
Have a look at http://atlanticgreen.com/nhth.htm
- Joined
- Apr 1, 2012
- Messages
- 71
Steve, thanks for the link. Looks like my head is a 69-70 Commando not a 71. Head is supposed to be a Hemmings big valve, I have photos taken during assembly which show the casting number. Bike is totally assembled, so I'll pull the carbs and manifolds off to see what the ports are. Motor has very few hours, built during restoration of the bike. Also 0.020 over bore, superblend bearings. Will get build notes, paperwork, receipts which should tell more.
- Joined
- May 28, 2003
- Messages
- 2,590
wot
68-69-70
Such a shame the heads get sent off for "ricky racer" prep and often do not do what was hoped for. Long time ago: A local club member had a combat head sent to Hemmings for the treatment... possibly pioneered by dunstall. I have a Dunstall head exactly like that on the engine table, just behind me.
The friend and I were both at a club open track session at NHIS. He had the big bucks hemmings head and I temporarily had a std 1971 RH1(28.5mm) head on my combat (cam) bottom end. We would come out of a turn and I would pull away while he was building rpm it would finally make power and catch up and go by me. Without a close ratio box the normal wide ratio hurt him but not me. He was not staying "on the boil". If he had the close ratio box I would have had no chance...
Going to race it, then fine. On the road I'd rather have a RH1 than a RH3 combat "big port". Hemmings big valve on a street bike seems to me for bragging rights only...IMO
good luck
68-69-70
Such a shame the heads get sent off for "ricky racer" prep and often do not do what was hoped for. Long time ago: A local club member had a combat head sent to Hemmings for the treatment... possibly pioneered by dunstall. I have a Dunstall head exactly like that on the engine table, just behind me.
The friend and I were both at a club open track session at NHIS. He had the big bucks hemmings head and I temporarily had a std 1971 RH1(28.5mm) head on my combat (cam) bottom end. We would come out of a turn and I would pull away while he was building rpm it would finally make power and catch up and go by me. Without a close ratio box the normal wide ratio hurt him but not me. He was not staying "on the boil". If he had the close ratio box I would have had no chance...
Going to race it, then fine. On the road I'd rather have a RH1 than a RH3 combat "big port". Hemmings big valve on a street bike seems to me for bragging rights only...IMO
good luck
baz
VIP MEMBER
- Joined
- May 26, 2010
- Messages
- 7,326
George Meszlenyi of Mez porting told me that he did most of the Mick hemmings big valve big port heads so it doesn't surprise me
He was big port mad and compression mad and twin plug mad with triple plugs in some of his Ducati heads although he did give up with that and went back to two plugs
He's sadly no longer with us ,his tuning seemed to me as I'm a complete layman to be all about very top end tuning
He built an engine for a triumph Saxon that did well at Daytona in the mid 90s
- Joined
- May 28, 2003
- Messages
- 2,590
baz
yes heard of mez. Wonderful to be able to do this kind of work for the right application. For a street NHT it's seems so over the top for a street bike. Even for a race bike that need SO much additional work to make it stay together like nourish cranks carillo rods, beehive springs on skinny 7mm? stemmed valves. It's not even a norton any more... I raced an MGB in the 70's and won our club championship 2 years. I built the car chassis and engine always myself alone. Pit crewed in the 90's for 3 vintages racing team 2 norton and 1 BSA. I even got my beginners drivers certificate.
I quickly found I'm a better engineer tuner mechanic
than rider...
A friend is trying to get me to drag race my norton with him this summer. before 2017 I was almost 190 lbs, but now I'm 165lbs and again fit in my leather suit.
Another friend in our NENO club races a nitrous hayabusa maybe I should challenge him to a grudge match...LOL
https://www.nedragway.com/
yes heard of mez. Wonderful to be able to do this kind of work for the right application. For a street NHT it's seems so over the top for a street bike. Even for a race bike that need SO much additional work to make it stay together like nourish cranks carillo rods, beehive springs on skinny 7mm? stemmed valves. It's not even a norton any more... I raced an MGB in the 70's and won our club championship 2 years. I built the car chassis and engine always myself alone. Pit crewed in the 90's for 3 vintages racing team 2 norton and 1 BSA. I even got my beginners drivers certificate.
I quickly found I'm a better engineer tuner mechanic
than rider...A friend is trying to get me to drag race my norton with him this summer. before 2017 I was almost 190 lbs, but now I'm 165lbs and again fit in my leather suit.
Another friend in our NENO club races a nitrous hayabusa maybe I should challenge him to a grudge match...LOL
https://www.nedragway.com/
- Status