FullAuto heads back in production

Alan L said:

Hi,
what performance/ reliability increases can we reason expect from the new head over original?
Alan

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Form what I'm reading:

Reliability:

1. It's a less porous and stronger grade of alloy, 356, not RR53B. (hopefully this will mean less likelihood of exhaust retaining nut threads stripping)

2. There are thread inserts for the 3 studs, making these stronger

3. the valve seats are upgraded

Performance:

1. The valves are standard size but the ports flow better, apparently it is not possible to get the same amount of flow without altered valve angles and a lot of stuffing round on stock heads.

2. More precise machining means both combustion chambers and all ports should be mirror images of each other


The cost for me means while my stock head's still going strong, no leaks, no detectable valve recession etc, I'll stick with that until it does have problems.

There appears to be very little negative comment online, nd much positive, that I could find, apart from one report of tappet cover stud holes needing to be tapped deeper, easily fixed.

seattle##gs said:

does anyone make tapered wrist pins for Norton? That would make the piston assembly a little bit lighter, anything helps. If you are balancing your crank. JS makes tapered pins for his own pistons but not for the regular pistons.
I called Ro-Dy a while back and he said he was retiring.

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marinatlas said:

RGM LIGHTWEIGHT GUDGEON PIN, 750 TWINS

050206 RGM NORTON GUDGEON PIN

www.rgmnorton.co.uk

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STD 750 = 68 G vs 61 G ( lightweight one ) same for 850 72 G vs 65

Very good...thanks.

Satan's Aardvark said:

.........

Performance:

1. The valves are standard size but the ports flow better, apparently it is not possible to get the same amount of flow without altered valve angles and a lot of stuffing round on stock heads.

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I don't think you have grasped the valve re-angle argument.....

With standard valves sizes you don't need to re-angle the valves, standard or Fullauto. The re-angle is to accommodate those valves, and in most cases compromises flow to some degree! The hope is that by working the port and using the bigger valves, you improve overall flow figures. But it isn't the re-angle that in itself delivers flow.

I am running a race engine with an Australian made Fullauto with standard valve sizes and standard valve angle. As a package, it works very well, delivers good mid-range, is free revving and is very easy to ride for the 'average' rider (me!).

However, it is a short stroke 750, and is about the limit of development for a Commando motor with standard valves.

Most automatically go to a larger valve, personally I am glad I didn't. On the other hand, I am running a larger carb bore and longer inlet manifold than most!

With a Fullauto port design (courtesy of Jim Comstock) you get better flow rates. Of course, it can be improved, pretty much anything can, until you go too far!

If I chose to build an 850 or larger motor I would expect to use larger valves. To use larger valves, you need to re-angle the valves, primarily to avoid valve clash.

The benefits of an American made Fullauto can be judged against two standards. Against a Standard Head, and against an Australian made Fullauto.

The Australian product was good and far better than an old original head on all counts, but as we have seen, with fresh investment it has been improved.

The US (STS) product adds, as you note, better materials, better machining processes and thereby better tolerances. I am sure the development hasn't finished.

But today, the product is a great basis for a long lasting road motor and a good race motor, even without modification.

Even better for a race motor will be an STS Fullauto head delivered with valves, ports and angles designed for them....I suspect that will come in time.

(And I expect even then someone will buy one and then further modify it, sometimes tuners can't help themselves.)

But if you are building a bike for road use or anyone less than a proven race winning rider, don't wait.

Satan's Aardvark said:

Form what I'm reading:

(Snip)

Technical Details on the New FullAuto Commando Cylinder Head from STS, in the US.

I had an opportunity to visit Special Tool Solutions in Jacksonville, Florida USA, and have a look at their new-version Full-Auto cylinder heads for Norton Commando motorcycles and tour the facility where they're made.. I was amazed at the design and quality of construction of these heads...

www.accessnorton.com

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As I was recently taken to task for discussing Norton performance parts in a thread about Norton performance parts, I take it kindly that you're referring to my original post. I worked closely with the management at STS to put together what I hope is a useful and comprehensive review of the details of the STS head (one of which I own and am enthusiastic about adding to my engine build in progress).
With kind regards, B H
(Norton factory, Wolverhamton, 1972 - 1974
Norton-Triumph distributors, California 1975 - 1976
Norton Rotary Project, Shenston, 1976 - 1978.)