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Full aouto head

Classic Norton Commando Motorcycles.

Full aouto head

Postby Swetune » Fri Aug 11, 2017 2:30 am

Any one that have a 850 Full auto used or new head for sale?

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Re: Full aouto head

Postby Fullauto » Fri Aug 11, 2017 3:36 am

Yep! Me. In a few weeks. See you PM.
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Re: Full aouto head

Postby norton73 » Fri Aug 11, 2017 7:16 am

Hmmmm...I wonder if I can sneak one with a Comnoz port job past the wife...
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Re: Full aouto head

Postby gortnipper » Sat Aug 12, 2017 1:42 am

norton73 wrote:Hmmmm...I wonder if I can sneak one with a Comnoz port job past the wife...



comnoz wrote:So now that I identified a problem with my prior velocity readings and corrected them -here is the flow tests with the 1.5mm oversize intake and a little work in the valve guide and bowl area.

Nice improvement for a steetbike running a .400 lift cam.

Flow
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Velocity
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Re: Full aouto head

Postby trident sam » Sat Aug 12, 2017 3:55 am

norton73 wrote:Hmmmm...I wonder if I can sneak one with a Comnoz port job past the wife...


That would be easy for me.
The only head I couldn't sneak past my missus would be George Clooneys :shock:

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Re: Full aouto head

Postby Swetune » Sat Aug 12, 2017 7:12 am

Fullauto wrote:Yep! Me. In a few weeks. See you PM.


Ok PM sent

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Re: Full aouto head

Postby Swetune » Sat Aug 12, 2017 7:15 am

norton73 wrote:Hmmmm...I wonder if I can sneak one with a Comnoz port job past the wife...


That would be interesting on the short stroke...
Comparing my Maney stage II porting to the Fullauto with Comnoz porting on the dyno.
The stage II 750 now has 72 Rear wheel Hp unfortunately just 3 runs on dyno as ignition broke down so didn't get to set advance and the right jetting

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Re: Full aouto head

Postby acotrel » Sat Aug 12, 2017 2:08 pm

With fitting the head to a short stroke motor, it is not simply a matter of one plus one equals two. If the head is designed to give max in a rev-range from 4 to 7, you might not get the result you might expect when you run it at much higher revs - the inlet ports might need to be larger, then other things change. From long-stroke to short-stroke, the mindset is different.
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Re: Full aouto head

Postby Swetune » Sat Aug 12, 2017 2:39 pm

acotrel wrote:With fitting the head to a short stroke motor, it is not simply a matter of one plus one equals two. If the head is designed to give max in a rev-range from 4 to 7, you might not get the result you might expect when you run it at much higher revs - the inlet ports might need to be larger, then other things change. From long-stroke to short-stroke, the mindset is different.


It has been shown a lot of times from tuners that there are different ways to go to flow a head. Both smaller valves or with larger valves port size and flow/ velocity. Axtell got som great figure with his std valve size. However the porting in respect to some areas should always be similar except for size of the port depending on carburetor bore size valve size and bowl area.
The full auto head will be thoroughly evaluated in regards to short stroke power band, cams, bore size and maybe even I would keep smaller size of valves as this might actually be beneficial. The Maney stage II is a good port job that can be done better but still the 750 short stroke with that head leaves 72 rear wheel Hp without any mods from my std setting 28 deg advance and 300 main jets . It will be interesting to see what the full auto with much better port geometry and matched combustion chamber would do on the dyno with the same bottom end, carbs and exhaust.

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Re: Full aouto head

Postby Fast Eddie » Sun Aug 13, 2017 2:09 am

Swetune wrote:
acotrel wrote:With fitting the head to a short stroke motor, it is not simply a matter of one plus one equals two. If the head is designed to give max in a rev-range from 4 to 7, you might not get the result you might expect when you run it at much higher revs - the inlet ports might need to be larger, then other things change. From long-stroke to short-stroke, the mindset is different.


It has been shown a lot of times from tuners that there are different ways to go to flow a head. Both smaller valves or with larger valves port size and flow/ velocity. Axtell got som great figure with his std valve size. However the porting in respect to some areas should always be similar except for size of the port depending on carburetor bore size valve size and bowl area.
The full auto head will be thoroughly evaluated in regards to short stroke power band, cams, bore size and maybe even I would keep smaller size of valves as this might actually be beneficial. The Maney stage II is a good port job that can be done better but still the 750 short stroke with that head leaves 72 rear wheel Hp without any mods from my std setting 28 deg advance and 300 main jets . It will be interesting to see what the full auto with much better port geometry and matched combustion chamber would do on the dyno with the same bottom end, carbs and exhaust.


Indeed that will be VERY interesting to see the effect of the FA head with all other parameters remaining the same.

I did that with the Comnoz head job on my RH10 head and was staggered to see a 9bhp gain and much healthier curve everywhere from 3000rpm onwards.

Please keep us all posted.
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Re: Full aouto head

Postby Brooking 850 » Sun Aug 13, 2017 2:41 am

Nigel, what was the end output of your RH10 head and did Jim put in oversize Vv's?
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Re: Full aouto head

Postby Fast Eddie » Sun Aug 13, 2017 3:52 am

Brooking 850 wrote:Nigel, what was the end output of your RH10 head and did Jim put in oversize Vv's?
Regards mike


Details are in this thread Mike: engine-build-prep-t18461-165.html?hilit=Cylinder%20head%20testing%20Dyno

'Befroe' spec of bike was: JS1 cam/ follower/ spring kit, JS rods and pistons at 10.5:1 CR, nice squish (forget exact measurment), 35mm FCRs, cNw manaiflod, Tri spark, cNw coils and leads. Standard RH10 head and valves.

'After' spec is: as above plus, followers ground to 7/8th radius instead of 1 1/8, 3mm OS re-angled inlet valves, 1.5mm OS exhaust valves, Comnoz port job, Comnoz valve springs.

Actual peak figure was 64.6bhp @ 6300 rpm, with a very flat power graph from 6000 to 7000.

There was significantly more power from 3000 upwards.

I was very surprised by this to be frank, the improvement way exceeded my expectations.
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Re: Full aouto head

Postby nortonspeed » Sun Aug 13, 2017 4:23 am

Fast Eddie wrote:
Swetune wrote:
acotrel wrote:With fitting the head to a short stroke motor, it is not simply a matter of one plus one equals two. If the head is designed to give max in a rev-range from 4 to 7, you might not get the result you might expect when you run it at much higher revs - the inlet ports might need to be larger, then other things change. From long-stroke to short-stroke, the mindset is different.


It has been shown a lot of times from tuners that there are different ways to go to flow a head. Both smaller valves or with larger valves port size and flow/ velocity. Axtell got som great figure with his std valve size. However the porting in respect to some areas should always be similar except for size of the port depending on carburetor bore size valve size and bowl area.
The full auto head will be thoroughly evaluated in regards to short stroke power band, cams, bore size and maybe even I would keep smaller size of valves as this might actually be beneficial. The Maney stage II is a good port job that can be done better but still the 750 short stroke with that head leaves 72 rear wheel Hp without any mods from my std setting 28 deg advance and 300 main jets . It will be interesting to see what the full auto with much better port geometry and matched combustion chamber would do on the dyno with the same bottom end, carbs and exhaust.


Indeed that will be VERY interesting to see the effect of the FA head with all other parameters remaining the same.

I did that with the Comnoz head job on my RH10 head and was staggered to see a 9bhp gain and much healthier curve everywhere from 3000rpm onwards.

Please keep us all posted.



The factory short stroke 750 engine with RH7 head and Omega domed high compression pistons is a perfect match regarding the shape of the combustion chamber hemisphere (without squish band). As a matter of fact the shape of the RH7 head hemisphere in combination with the domed pistons work like squish. Using the Full Auto head (or any other Commando head with a squish band) in combination with Omega shaped piston heads will not work because the gasses will be trapped in the outer space between hemishere and domed part of the piston. So this combination will either need machining the head (reshape the squish band) or another shaped piston head so that the gasses will be squished towards the centre in stead of (partly) getting trapped :!:
Last edited by nortonspeed on Sun Aug 13, 2017 6:07 am, edited 1 time in total.
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Re: Full aouto head

Postby grandpaul » Sun Aug 13, 2017 5:51 am

Fast Eddie wrote:'After' spec is: as above plus, followers ground to 7/8th radius instead of 1 1/8...

7/8" radius on the follower faces????

That's smaller than a roller lifter, isn't it?
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Re: Full aouto head

Postby Fast Eddie » Sun Aug 13, 2017 12:45 pm

grandpaul wrote:
Fast Eddie wrote:'After' spec is: as above plus, followers ground to 7/8th radius instead of 1 1/8...

7/8" radius on the follower faces????

That's smaller than a roller lifter, isn't it?


Don't know about roller lifters.

Remember we are talking JS1 cam kit here, therefore BSA lifters.
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