Development of the Commando engine

I would be interested to know if there is a book which covers the development of the Commando engine and discusses the business relationship between Joe Craig and Bert Hopwood. I have owned several 650 Triumphs, and my 850 engine is very different in head and crankshaft design. The 500cc Domiracer which Tom Phillis raced would probably not have had similar centre of gravity to a Manx, but still a 100 MPH lap of the IOM. The 650SS seemed to be excellent. One of my friends has an Atlas with a rebalanced crank - he won a lot of races with it in the1960s.
I suggest Norton must have tried a lot of variations in engine design.

Joe Craig had nothing to do with Norton twin development and had a well known distaste for them.
The only multi cylinder projects he was involved in were:
1. AJS Porcupine development with Phil Irving (40's), and
2. Vanwall four cylinder racing car engine (an assembly of 4 Norton 500 singles) for the millionaire Tony Vanwall, (50's).

acotrel said:

I would be interested to know if there is a book which covers the development of the Commando engine and discusses the business relationship between Joe Craig and Bert Hopwood. I have owned several 650 Triumphs, and my 850 engine is very different in head and crankshaft design. The 500cc Domiracer which Tom Phillis raced would probably not have had similar centre of gravity to a Manx, but still a 100 MPH lap of the IOM. The 650SS seemed to be excellent. One of my friends has an Atlas with a rebalanced crank - he won a lot of races with it in the1960s.
I suggest Norton must have tried a lot of variations in engine design.

Click to expand...

https://www.classicmotorcycle.co.uk/norton-800cc-dohc/
A commando engine is basically a tuned up atlas engine that was put into a chassis that didn't vibrate when the dohc 800 didn't work out designed over a 6 week period so they had something new to show at the 1967 earls court bike show

baz said:

https://www.classicmotorcycle.co.uk/norton-800cc-dohc/
A commando engine is basically a tuned up atlas engine that was put into a chassis that didn't vibrate when the dohc 800 didn't work out designed over a 6 week period so they had something new to show at the 1967 earls court bike show

Click to expand...

And the Atlas is a direct descendant of the original 500 cc Model 7 twin.

I suggest that Joe Craig and Bert Hopwood might have been contemporaries. Getting the cylinder head so correct shows they knew something which Triumph did not. Their racing development history of the Manx would be interesting. I wonder what the combustion chamber shape was in the SOHC race motors. One of my mates has a Triton with a bigger than 650cc Triumph motor, and has won several historic championships with it. It has Puma cases, Nourish crank and Bonneville cylinder head. He still says he cannot beat the Nortons. - that is in the pre-1963 class. In the pre 73, class the 1100cc methanol fuelled CB750 Hondas are fast, but Nortons still give them worries.
When I built my Seeley 850, I never believed in it - now I think differently.
A thing I have noticed about genuine pre 1963 Manx Nortons, - it is almost impossible to get more trail on the steering. How would they arrive at that point ?

acotrel said:

I would be interested to know if there is a book which covers the development of the Commando engine and discusses the business relationship between Joe Craig and Bert Hopwood. I have owned several 650 Triumphs, and my 850 engine is very different in head and crankshaft design. The 500cc Domiracer which Tom Phillis raced would probably not have had similar centre of gravity to a Manx, but still a 100 MPH lap of the IOM. The 650SS seemed to be excellent. One of my friends has an Atlas with a rebalanced crank - he won a lot of races with it in the1960s.
I suggest Norton must have tried a lot of variations in engine design.

Click to expand...

Imagine how many more races your mate with the atlas could have won with a commando engine fitted !
I'm guessing this was well before the commando came out?

baz said:

Imagine how many more races your mate with the atlas could have won with a commando engine fitted !
I'm guessing this was well before the commando came out?

Click to expand...

I don't know how good the Atlas engine is. If the pistons are lighter it might be better. With the one Bob has, he fitted with MAP pistons and rods, and the balance factor is around 80%. Many years ago (1963) I watched Jack Forrest at Bathurst beat all the Manx Nortons with a 650SS. He really gave my mate the shits. Forrest was a works rider for BMW, he used to tell the other riders he was going to beat them, and then do it.
I have ridden a 1961 500cc Manx Norton - it was quicker in corners that it was slower down the straights. A Commando is probably double that. A featherbed Commando might have a problem with weight distribution. You would not know until you tried to race it. I saw one at a race meeting a few years ago. But the kids tend to ride around the bike and not fix the problems.
I usually know when I am likely to crash, from the feeling in my stomach when I am in the middle of a corner. I learned to race by crashing.

rohan
Joe Craig had something to say about the inlet manifold design of the 1st iron dommie engine. Apparently it was hopeless, and killed the performance (it was like the early BSA long stroke twins). Amending it to get the performance back, with the little alloy manifold bolted on delayed production for a few months ?, but Bert would never admit there was even a problem....

Joe Craig norton

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