Full Auto Update

Correction, Commando intake valves are not 1.5," they are 1.48".
Atlas and P11 intake valves are shown as 1.5"
Going back to the beginning of the Doug Hele production downdraught head with the 61 Manxman then 62 650ss, the intake valve was boosted to 1.406" size. The 600s had smaller intake valves.
When Norton increased the bore to make the 750 Atlas, they increased the intake valve size again, this time to 1.5"
When the Commando version of the engine came along, Norton reduced the intake valve size by a tiny bit to 1.48"
They kept that size for all standard Commandos, as near as I can tell.
Strange that the Commando version of the 750 with 58 bhp used slightly smaller valves than the 49 bhp Atlas 750.
Norton must have felt the intakes were a bit too large on the Atlas/P11.
This info is based on valves listings for various models shown on the Andover site.

Glen

edgefinder said:

In the interview of an old guy from the Norton factory who died last year he mentioned a law in the UK that limited 750 twins to a 1.5" intake valve.

Click to expand...

Is that a joke (serious question)?

I am quite certain that is not true. And even if it was, it doesn’t explain why it stayed the same on the 850.

Fast Eddie said:

Is that a joke (serious question)?

I am quite certain that is not true. And even if it was, it doesn’t explain why it stayed the same on the 850.

Click to expand...

Agreed - total bollocks! T140 inlet valve 1.594", exhaust 1.437".
Sort of emphasises the point that bigger valves wouldn't go amiss on a 750, let alone 850 or 920...

On the subject of re-angling, I have a 750 head which had been ported and fitted with PR inlet valves, but not re-angled.
I had to cut the seats a long way back to get rid of valve clash with a 4S cam (It originally had a 3S), so whether a good idea or not, re-angling the valves is the only solution.
Still a bit baffled as to why it's such a bad idea, but what do I know?

The 650 head has the same valve layout as the 750. The 650 std valves were 1.4 but the 650SS valves were 1.5". The valve locations and angles are the same as on the 750 except that the bore is offset (a waste of space that could use the advantage of bigger valves).

When fitting bigger valves in the head you can have valve clash so you either have to reangle them, or sink the valves deeper into the seats, or radius the lifters so there is less cam duration. All these options give more clearance between the valves but they can result in performance loss due to reduced flow (or reduced cam duration). It the case of reangled valves the valve is canted so the near side of the valve ends up deeper in the seat - this means that the short side of the port radius ends up shorter and tighter near the seat and that's not good for flow. But when you install a larger diameter valve you more than make up for this short coming and the net result is more power. The full auto head works better because the floor is raised so the short side port radius is longer - so you are already ahead with the Full Auto head.

Same thing happens when you sink the valve into the head to avoid valve clash - you tighten the short side port radius. But if you sunk the valves because you went to 1.5mm oversize valves or went to a hotter cam with 102 lobe centers (instead of 104 lobe centers using the same lobes) you may have more than made up for the shorter port radius and again the result could be more power.

Ideally you would move the valve guide without reangling it to make room for larger valves. But you have reangle if you use the same rocker arms, rocker arm and pushrod locations. And you are definitely going to get more flow with the bigger valves throughout the lift of the valve - from low lift to high lift. And that's going to increase performance from mid range to high RPM.

If you want bigger valves without reangling - well dream on. If you want more performance and efficiency with what works and what is available then go for the bigger reangled valves and enjoy it.

See port image below. Study the short side port radius near the valve seat. The HD XR 750 port is what a Full auto port would look like with reangled bigger valves and its going to give more performance throughout the mid range and higher RPM.



Note that Kibblewhite currently offers 1.5" stock size intake valves and 1.5mm oversize intake and exhaust valves. Stever Maney offers 3mm and 5mm oversize intake valves and 3mm oversize exhaust valves for stage 2 or stage 3 heads.

lcrken said:

Steve Maney's 100hp for the 1007 cc engine is crankshaft hp, obtained by using a correction factor on the measured rear wheel hp. Measured rear wheel hp, corrected to standard temperature and pressure, was 86 hp at 5056 rpm.

Ken

Click to expand...

I haven't asked Steve personally but from his website is the following, could it be a miss print?

I think the most memorable milestones were winning Daytona the first time, and getting over 100 BHP out of my 920 motor.

storm42 said:

I haven't asked Steve personally but from his website is the following, could it be a miss print?

I think the most memorable milestones were winning Daytona the first time, and getting over 100 BHP out of my 920 motor.

Click to expand...

Yes, the 100+ was from a 920, before any 1007's had been built

Seeley920 said:

Yes, the 100+ was from a 920, before any 1007's had been built

Click to expand...

Would that have been at the wheel? It seems like a very Japanese thing to do quoting crank HP without stating it. In the conversations I have had with Steve he has never come across as a cock swinger, always very matter of fact with a typical Yorkshire, I don't care if you believe me or not attitude.

storm42 said:

Would that have been at the wheel? It seems like a very Japanese thing to do quoting crank HP without stating it. In the conversations I have had with Steve he has never come across as a cock swinger, always very matter of fact with a typical Yorkshire, I don't care if you believe me or not attitude.

Click to expand...

The dyno he used was a rear-wheel reading. I can't remember whose it was offhand, but I did see the printouts at the time.

Steve has no reason to bullshit anyone, his bikes were very quick. Proof of the pudding etc

storm42 said:

I haven't asked Steve personally but from his website is the following, could it be a miss print?

I think the most memorable milestones were winning Daytona the first time, and getting over 100 BHP out of my 920 motor.

Click to expand...

No misprint. I posted what info I could on the Ron Wood, Herb Becker, and Steve Maney (1007) engines because those are the engines Jim talked about in his post. I have no doubt Steve eventually managed to make 100 hp at the crank with his 920 engines. Back in 2000 he was making over 80 hp at the rear wheel from his 920, and later 87.9 hp, which would convert to something close to 100 crankshaft hp. It's quite reasonable to assume that he had managed to coax out a few more horses in the following years. The 1007 numbers are from 2013. The difference between the 920 and 1007 is not a matter of much more maximum horsepower. The big gain is a massive hp gain in the mid-range, which translates to a lot more grunt out of corners.

FWIW, when Steve won at Daytona in 2004 he was racing with his short stroke 750 engine. He was riding with support from my team, Left Coast Racing. We were racing in the Singles classes, with Steve running his Norton in classes for twins. Between us we won races in three different classes, including Steve's win. It was a fun time for all.

This is a picture of the team at that race with their trophies. Plenty of big grins on the rider's faces.



This is picture of our pit setup, with my bikes lined up in the foreground, and Steve's bike back next to the trailer. That's Steve bending over in the trailer.



Ken

JS ENg wrote
"The 650 std valves were 1.4 but the 650SS valves were 1.5"

Not according to Atlantic Green, Andover Norton, or the N.O.C
If I use either the part number in my 650SS parts book or Andover's parts diagram to order an intake valve from Andover Norton, it gives valve diameter as 35.7 mm , which is 1.406"


Glen

Seeley920 said:

The dyno he used was a rear-wheel reading. I can't remember whose it was offhand, but I did see the printouts at the time.

Steve has no reason to bullshit anyone, his bikes were very quick. Proof of the pudding etc

Click to expand...

The Dyno charts I have from Steve for 750 and 920 engines were from Hobbsport Racing in Keighley. The 1007 charts don't have a company name on them, but I think it is likely they are also from Hobbsport. The earlier tests were done on a Dynojet 150 dyno. I don't know about the later tests. They span a 13 year period, and it's possible the dyno may have been upgraded at some point.

Ken

lcrken said:

The Dyno charts I have from Steve for 750 and 920 engines were from Hobbsport Racing in Keighley. The 1007 charts don't have a company name on them, but I think it is likely they are also from Hobbsport. The earlier tests were done on a Dynojet 150 dyno. I don't know about the later tests. They span a 13 year period, and it's possible the dyno may have been upgraded at some point.

Ken

Click to expand...

Yes, that was it

worntorn said:

JS ENg wrote
"The 650 std valves were 1.4 but the 650SS valves were 1.5"

Not according to Atlantic Green, Andover Norton, or the N.O.C
If I use either the part number in my 650SS parts book or Andover's parts diagram to order an intake valve from Andover Norton, it gives valve diameter as 35.7 mm , which is 1.406"


Glen

Click to expand...

worntorn said:

JS ENg wrote
"The 650 std valves were 1.4 but the 650SS valves were 1.5"

Not according to Atlantic Green, Andover Norton, or the N.O.C
If I use either the part number in my 650SS parts book or Andover's parts diagram to order an intake valve from Andover Norton, it gives valve diameter as 35.7 mm , which is 1.406"


Glen

Click to expand...

I depends who you want to believe. The specs below are from the Haynes Norton twins repair manual (1957 -1970). That manual doesn't even show 1.4 valves for the 650SS (only 1.5). They can be either way. I've had 650 customers who have ordered 1.4 valves and others who have ordered 1.5 valves. I suspect the later 650SS heads had the 1.5" valves.

Haynes is best ignored as a source for such things.
I have the official pre-Commando twin parts books from Norton, both early and late.
There are two inlet valves listed for the 650ss, an early and late. They differ in length but both are 1.406" in diameter.
My 1968 650ss has 1.5" inlet valves. They were at 1.406" from the factory, but then it dropped a valve and went to Herb Becker for repair. ( and an unsolicited porting job!)

Glen

There are lies, damn lies and Haynes workshop manuals!
If I'd followed their instructions on timing my Ducati I would have been drenched in oil and probably killed the motor as well.

That said, those numbers correspond to the 650 Manxman (1.406") vs the Atlas (1.5"). Can't find 650SS Data - will have to check my 650SS head next time I'm in the garage.

I send what the customers ask for. Some 650SS customers ask for 1.4 intake valves. Some ask for 1.5" intake valves. They need whatever fits the 650SS head they have on hand and I don't argue with them. Maybe like you Worntorn - they have converted to larger valves - its fine with me either way. Currently I am sending out a set with 1.406" custom black diamond intake valves (with beehive springs) to a 650SS customer.

Please - lets get this thread back on track to John's Full Auto heads.

G81 Can Cycle said:

Jim

We will first start with a standard set up. The core boxes that establish the cores for the intake passage have features that are fixed for the valve guide. once we have this running well, we might cast some heads without cores for the intake passage, thos will allow for CNC machining of the intake port (raised floor ect) and changing the intake valve angle

Click to expand...

John,
The pattern maker should be able to computer model the casting flow properties with those cores removed. Sometimes a small change may need the pour system to be modified as well to prevent turbulent flow, adjust fill speed and shrinkage, etc.

Jseng wrote
"Please - lets get this thread back on track to John's Full Auto heads."

Sure, as long as we keep the information accurate. Norton did use bigger valves when bumping to the 750cc engine. That needs to be noted, not that they made yet another mistake by using the wrong valve size, a holdover from the 650 as you indicated.

The interesting thing I learned is that they went back a bit in size with the Commando.
I would love to know why, but I'll take that up elsewhere.

Glen

G81 Can Cycle said:

Jim

We will first start with a standard set up. The core boxes that establish the cores for the intake passage have features that are fixed for the valve guide. once we have this running well, we might cast some heads without cores for the intake passage, thos will allow for CNC machining of the intake port (raised floor ect) and changing the intake valve angle

Click to expand...

John

If that happens I think it will be a welcomed option by many customers. Many have paid extra for re-angled big valves in the past and more will follow.

The FA port floor is already raised. All you have to do is tilt the guide, the valve seat along with it and match the port to the seat. If you keep the guides at 1/2" diameter then you will be offering something that has never been available before. You would be providing one of the most significant Norton head upgrades since the advent of the FA raised port floor. While you're at it your could clean up the shape of the exhaust port floor as that was a bit too rough with the original FA heads.

jseng1 said:

John

If that happens I think it will be a welcomed option by many customers. Many have paid extra for re-angled big valves in the past and more will follow.

The FA port floor is already raised. All you have to do is tilt the guide, the valve seat along with it and match the port to the seat. If you keep the guides at 1/2" diameter then you will be offering something that has never been available before. You would be providing one of the most significant Norton head upgrades since the advent of the FA raised port floor. While you're at it your could clean up the shape of the exhaust port floor as that was a bit too rough with the original FA heads.

Click to expand...

So the AMA (RH2) heads didn't have this feature?