Merlin DOHC Progress (2018)

I've done some work on a yamaha bike that was a parallel twin with a double overhead cam. It drove it's cams with a gear on the crankshaft centrally located between the cylinders with a chain that linked the cams above to the crank below. How do you plan on driving the overhead cams on the norton I wonder?? Bevel gear drive? chain drive ? something on the timing side off the crank gear? something else??
 
I've done some work on a yamaha bike that was a parallel twin with a double overhead cam. It drove it's cams with a gear on the crankshaft centrally located between the cylinders with a chain that linked the cams above to the crank below. How do you plan on driving the overhead cams on the norton I wonder?? Bevel gear drive? chain drive ? something on the timing side off the crank gear? something else??


Like a G50 Matchless ? - might work. With the original 4 valve Ducati heads which were on Kevin McGee's bike in Australia, the belt drives used to give a lot of trouble.
 
Won't the height of the motor be a problem when you come to install it into a frame ?
 
Good question, measuring the height of a spare RH4 head and comparing it to the drawing the Merlin is quarter of an inch taller. I don't know what frame i will put it in, the originals were used in sidecarcross frames.
 
1/4”... is that all? I expect much more than that to make space for the cams?
 
Good question, measuring the height of a spare RH4 head and comparing it to the drawing the Merlin is quarter of an inch taller. I don't know what frame i will put it in, the originals were used in sidecarcross frames.

There was mention in a MCW article in 1980 on the Merlin bout one being used in a stock frame, but no pictures were included. This is a snip from the article.

Merlin DOHC Progress (2018)


Ken
 
A friend and I have recently acquired the Merlin DOHC engine mentioned in the article above. It is pretty tired looking but complete and apparently ran really well back in the day. I know this is an old thread, but is there still interest in these engines and does it have any value? Dobba99, are you still working on this project? It would be great to know more about the engine. We acquired it as part of a job lot of other spares and are not sure whether to restore it or sell it on. We also have the bike the engine was originally fitted in; it currently has the shell of a turbo charged 850 motor in it and some great chassis upgrades (Astralite wheels, Spondon front end etc). Unfortunately we are new to Nortons but know more about BSA triples and twins so would appreciate any info. Thanks.
 
A friend and I have recently acquired the Merlin DOHC engine mentioned in the article above. It is pretty tired looking but complete and apparently ran really well back in the day. I know this is an old thread, but is there still interest in these engines and does it have any value? Dobba99, are you still working on this project? It would be great to know more about the engine. We acquired it as part of a job lot of other spares and are not sure whether to restore it or sell it on. We also have the bike the engine was originally fitted in; it currently has the shell of a turbo charged 850 motor in it and some great chassis upgrades (Astralite wheels, Spondon front end etc). Unfortunately we are new to Nortons but know more about BSA triples and twins so would appreciate any info. Thanks.
Could you post some pictures?? I think it has to be of interest to a lot of people on this forum, Thanks for your post. Chuck.
 
Yes, I will post some later this week. The engine is off having a special crank nut turned up but should be back in a few days.
 
I like the name.... My advanced gearhead buddy nicknamed my Triumph Rocket III "Merlin" for me. Stating that: "it sounds like a V-12 and flat-ass disappears from my Harley"
 
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I reckon just take a right hand cylinder head off of a Honda st1100 and bolt it on a 750 commando barrel
Use a dummy extended camshaft with a pulley on the drive side of the engine
Just drill some extra holes in the barrel to hold the head ,it already has 73mm combustion chambers
Then weld fins on the head or fit a small rad and water pump and bobs your uncle
Allen Milliyard would have that done in a morning!!
 

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A friend and I have recently acquired the Merlin DOHC engine mentioned in the article above. It is pretty tired looking but complete and apparently ran really well back in the day. I know this is an old thread, but is there still interest in these engines and does it have any value? Dobba99, are you still working on this project? It would be great to know more about the engine. We acquired it as part of a job lot of other spares and are not sure whether to restore it or sell it on. We also have the bike the engine was originally fitted in; it currently has the shell of a turbo charged 850 motor in it and some great chassis upgrades (Astralite wheels, Spondon front end etc). Unfortunately we are new to Nortons but know more about BSA triples and twins so would appreciate any info. Thanks.
Hello Bsamat
Yes, i still am progressing the Merlin. Sorry for not posting any updates on it for a while but last years (2019) major purchase was for the valves (got three complete sets made just to bring the price down to a sane level!) This year progress has been halted due to personal issues and the fact that I,m getting made redundant next year.
I'm extremely interested in the fact that one of these engines has resurfaced. Any chance of a look see at it? to see one in the metal would be great. Cam profiles, port shapes, everything like this is very useful. PM me please.
Regards
Peter
 
Glad you two have linked up. Well pleased. Brilliant project Dobba.
Bsamat love to hear about the rest of your find? Finally using my Astralites after buying them for my T160 "when I was a lad"
 
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