Another 8-valve attempt.

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RoadScholar said:
I think the Drouin proved the point that the head and cam(s) can produce more power than the bottom end can tolerate. So, you say you like look of an engine that has spit-in-your-eyes power adders? I applaud the engineering and craftsmanship that goes into such projects and the challenges that the builder overcomes; a good mix of art and science, and, if ridden with great restraint will provide the builder with years of satisfaction and a high sense of achievement.

I have no idea how much reliability the Westlake 8 valve head cost the pre oil-in-the-frame Triumphs, and there was a similar short lived 8 valve head offered from the factory for oil in frame Triumphs. Anyone have any comments about these.

My son built an '03 twin cam, supercharged Mustang Cobra form 390 HP to 720 HP, it didn't last long.

Your Norton won't last long either if you ask too much from a stock bottom end.

Best.
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Regarding the 8 valve top end for Triumph twins. I have always fancied fitting one to my TR7, but was told by Neil Beadling years ago that if attempting to extract more than around 65 HP from a unit motor the crankcases would start to crack. I was at the time looking at a 750 race engine on his bench which had had extensive strengthening/welding carried out. Even the Meriden attempt had a beefier crank.
I think most of these seriously modified engines are just exercises in engineering. For more power with reliability just buy a modern bike.
 
Matchless said:
Regarding the 8 valve top end for Triumph twins. I have always fancied fitting one to my TR7, but was told by Neil Beadling years ago that if attempting to extract more than around 65 HP from a unit motor the crankcases would start to crack. I was at the time looking at a 750 race engine on his bench which had had extensive strengthening/welding carried out. Even the Meriden attempt had a beefier crank.
I think most of these seriously modified engines are just exercises in engineering. For more power with reliability just buy a modern bike.
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Calling Fast Eddie....he once owned this one.
Another 8-valve attempt.
 
Ok Cab...

8 valves are an advantage mainly cos they allow higher flow WITH much higher velocity, so it’s a win-win. But you also get a better combustion chamber shape, the ability for bigger / better designed ports, correspondingly bigger cams and carbs, etc. In other words, it allows a complete redesign of the engine!

Yes it’s true, fitting an 8 valve top end to a stock Triumph bottom end can be a quick way of finding the weak link. Then when you fix that you’ll probably find the next, etc! Funnily enough I’ve actually heard idiots blame Edward Turner for this, like he shudda designed his bikes to withstand having their output doubled 50-60 years after being made!

Having said that, the original Rickman kit was only 686cc. Add in poorly timed cams, poorly set up carbs and poor exhaust pipes and it’s quite possible that many put out less power than stock, they’re probably the ones that lasted best!

I put a lot of miles on the TSS pictured above, about 30k ish I think. And it got freakin thrashed, it would frequently rev off of the dail, which goes up to 8k, but eventually the crank cases split through the drive side main bearing. Interestingly the rest of the bottom end was really good, cams and even big ends all near perfect. The TSS crank and rods is much stronger than the stock twin crank. Had Triumph survived, they were ready with stronger cases and a sorted top end. Seriously, the TSS was a knatts cock away from being an absolute cracker. But the one above has some serious engineering in it inc nickasil barrels, bronze skulls in the head, etc, etc so should be pretty bomb proof.

Cracking through the primary side main bearing is common ish. Often they will crack the timing side crank case through the cam bush centre line. Mainly only on race bikes though.

The simplified history of the Weslake / Nourish is that it started out as a top end kit for Triumphs, but broken rods, cranks and cases eventually lead to a complete engine being offered.

But anything is doable. Unit Triumph cases can have weld added in strategic places, billet cranks, splined gearbox mainshafts, etc and you've got a bottom end that’ll handle 900+cc and 84+rwhp with absolute reliability. I know cos I dunnit. But I was racing it. For a road bike there are cheaper and easier ways of achieving this ... along the lines of the advice from Matchless above...!

I‘m still saving a space in the shed for that TSS to come back home...
 
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Anyone who has studied the Commando lower ends more than just reading forum/fecebook posts, and listening to unsubstantiated stories, will have seen more per-capita blown Commando bottoms ends than both Triumph & BSA big wins COMBINED. That's significant beyond it's face, because of the sheer numbers of Triumphs & BSAs out there, as compared to the narrow production year range of Commandos.

Even beefy cases and better cranks can only go so far. It takes SERIOUS money to spin Commandos up (and, by then, they aren't REALLY "Commandos" any more), where they stay in one piece.
 
Dave Nourish told me when I was building up my original 8 valve Rickman 686 that I would; find it easier to start, that it did better miles per gallon, that it would pull all the way through the rev range, make 6 to 8 bhp more & be as reliable. What I found riding it was it had no flat spots, it pulled even in the wrong gear! I think I told you the story of the clutch washer going at Mallory. I couldnt change gear or find nuetral. I got soaked stripping it down ( no van in those days. I used to take the front wheel off the bike & push it on the rear wheel into my estate car. Me & my son slept in the car once the bike & tools were out) I couldnt find a spare. I put a crank shim in to see if I could get out on track. Anyway it didnt work. Found myself unable to come back down the box. In the wet around Mallory hairpin in 4th running down from the bus stop one arm on the tank waiting for it to pick up. Full bore into Gerrards thankfully no Edwinas. I had a blast! laughing at myself wondering what people were thinking. And I didnt finish last! Came off track to be stopped by the sound man. Couldnt find neutral, got pulled & had to have my wrist smacked by the clerk of the course.
All in all I think Dave was correct. The problem with the 8 valve is it went through 8500 revs before you could change up. I also found on the back straight at Snetterton that flat out in top it would start to pick up revs again & pull again through 9000 & It made speed. I remember the ghostly silence as I held my breather & thought it's bound to go bang
 
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Found this pic in a number of the Classic Bike Magazine from 1985, a Commando with a 1000cc Nourish motor. Is there any Norton bits in that at all? The crank case doesn´t look like Norton in any way.

Another 8-valve attempt.
 
They don't look like Norton cases because they are Nourish cases !

That’s a complete Nourish engine.

With todays availability of TTI boxes and the cNw electric leg and belt drive kit, that would make such an awesome bike!
 
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Chris said:
Dave Nourish told me when I was building up my original 8 valve Rickman 686 that I would; find it easier to start, that it did better miles per gallon, that it would pull all the way through the rev range, make 6 to 8 bhp more & be as reliable. What I found riding it was it had no flat spots, it pulled even in the wrong gear! I think I told you the story of the clutch washer going at Mallory. I couldnt change gear or find nuetral. I got soaked stripping it down ( no van in those days. I used to take the front wheel off the bike & push it on the rear wheel into my estate car. Me & my son slept in the car once the bike & tools were out) I couldnt find a spare. I put a crank shim in to see if I could get out on track. Anyway it didnt work. Found myself unable to come back down the box. In the wet around Mallory hairpin in 4th running down from the bus stop one arm on the tank waiting for it to pick up. Full bore into Gerrards thankfully no Edwinas. I had a blast! laughing at myself wondering what people were thinking. And I didnt finish last! Came of track to be stopped by the sound man. Couldnt find neutral, got pulled & had to have my wrist smacked by the clerk of the course.
All in all I think Dave was correct. The problem with the 8 valve is it went through 8500 revs before you could change up. I also found on the back straight at Snetterton that flat out in top it would start to pick up revs again & pull again through 9000 & It made speed. I remember the ghostly silence as I held my breather & thought it's bound to go bang
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Yup, 9,000rpm is gonna find the weak link in a Triumph eventually !
 
I found the photos: not Saab, but it was a Jim Comstock racer with one-piece VW diesel crank and many other mods too.
 
grandpaul said:
Anyone who has studied the Commando lower ends more than just reading forum/fecebook posts, and listening to unsubstantiated stories, will have seen more per-capita blown Commando bottoms ends than both Triumph & BSA big wins COMBINED. That's significant beyond it's face, because of the sheer numbers of Triumphs & BSAs out there, as compared to the narrow production year range of Commandos.

Even beefy cases and better cranks can only go so far. It takes SERIOUS money to spin Commandos up (and, by then, they aren't REALLY "Commandos" any more), where they stay in one piece.
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This is why the only Norton parts in my 920 Commando are the oil pump, timing gears & the rockers. I've broken two Norton cranks & split one drive side case. The second of those crank breakages very nearly cost me a serious accident.
 
Matchless said:
This is why the only Norton parts in my 920 Commando are the oil pump, timing gears & the rockers. I've broken two Norton cranks & split one drive side case. The second of those crank breakages very nearly cost me a serious accident.
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True, plus a cylinder head in my case lol. My friend Rob always says your no faster! Your just buying reliability. In the early 70s he broke a crank coming over the line at Lydden between the bearing & the primary drive. He also once broke the top off the crankcase & finished with the barrels moving with the pistons. Everytime I've had a major blow up I've been hurt. I'll take the reliability.
 
Matchless said:
The second of those crank breakages very nearly cost me a serious accident.
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Oh, my... I didn't even mention THAT aspect.

Even worse, the poor sap following the hapless rider who splits his cases on the track, ending up in hospital (or worse), when it had nothing whatsoever to do with HIM!!!
 
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The worst iron flywheel damage I ever saw was at a vintage race meeting at Cadwell in the early/mid eighties. One of the blokes racing a Featherbed ES2 failed to show up one or two laps from the finish. When he did arrive back in the paddock it was in the back of the breakdown wagon. The flywheels had gone bang in a big way, disintegrating the crankcases & leaving the top end of the motor hanging on the head steady. The bottom rails of the frame were also bent. He as far as I remember was uninjured.
 
Hello everybody,

very interesting subject, im for obvious reasons no norton expert but i would assume i´d have a fairly decent understanding of gas exchange and combustion in 4t engines.

So here are some of my points for whom it may interest:

1. sleeve or rotary valve would be very interesting but from my research on the subject most of the designs are either somewhat prone to seizing, leaking or other assorted problems while at least the sleeve engines used in airplanes and cars i´d reckon would have some troubles for the high rpm usage in bikes.
Only design would be the one that was used on daimler test WW2 fighter engines with rotary discs and functioning seals.
Unfortunately kind of hard to find good pictures on the DVL engine in whoses development also bensinger and wankel were to my knowledge involved.

2. i would not see why a 4v head would raise the rev range higher than on a 2v engine, given that for obvious reasons one would need to account for the gas speeds and correct valve timing.
Up to this day im still amazed that nobody every continued on the idea of a suitable 4 valve head for a commando as i know that the triumph/weslake/nourish heads despite (imho) some of their few shortcomings prove to work quite well.

3. Regarding the 4v trumpet heads:
personally i worked about 10 years ago on a couple of them and the flownumbers did not leave too much impressed due to for my understanding following facts:

Intake ports could be still raised by a good amount (with modern springs maybe even more)
port shape could be updated (which i did) with a whole lot wider short side turn and a less harsh short side turn.

Flow numbers where regarding to my memory somewhat higher than on a 2v engine but did not show that much gain in comparison which one would assume in a comparison between 2v and 4v.

my conclusion would be that a more modern design even of a 3-4V pushrod valve head should be doable and could prove an improvement if port shape would be updated and intake valve closure would take account of the different needs of a 4v pushrod engine.

Regarding the broken cranks and cases im inclined to think that with more efficient combustion less ignition advance could be used thus less strain would be transmitted to the crank case, but as said im no expert on limey bottom ends, although i was always amazed that one hears very rarely on squish area equipped norton combustion chambers.

kind greetings and happy new year

Christian
 
Matchless said:
The worst iron flywheel damage I ever saw was at a vintage race meeting at Cadwell in the early/mid eighties. One of the blokes racing a Featherbed ES2 failed to show up one or two laps from the finish. When he did arrive back in the paddock it was in the back of the breakdown wagon. The flywheels had gone bang in a big way, disintegrating the crankcases & leaving the top end of the motor hanging on the head steady. The bottom rails of the frame were also bent. He as far as I remember was uninjured.
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I think that might of been Mark Gunson riding Shane Lockley`s bike...Ooops. I was marshaling when he came coasting by with the front pipe dragging on the track. I picked up one of the pieces of shrapnel that accompanied him along the track, it was a bit of barrel fin with section of bore still attached. i think it also bent a top frame rail and put a hole in the bottom of the tank. "Thanks for the lend of the bike but it doesn`t rev like my Yam!"
When a Norton went bang at Mallory the other year, a large piece of flywheel landed on the shithouse roof. If it had of hit someone it could of easily killed them. You really shouldn`t use a standard flywheel in a race engine!
 
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