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Head flow testing.

Classic Norton Commando Motorcycles.

Head flow testing.

Postby comnoz » Fri Feb 04, 2011 10:08 pm

I would like to build up a database of flowtests on modified Norton heads. The tests would be done on one intake port and be from 0 to .450 lift and would include a single velocity measurement measured central in the port 3/4 inch in front of the guide.
If anyone has a modified head setting around that you are curious about and want to get it to me I will test it and pay the return freight. [domestic only] I will post the results here for all to see. It would need to be disassembled and I would need 2 valves. No springs or hardware. Jim
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Re: Head flow testing.

Postby hobot » Fri Feb 04, 2011 11:17 pm

Well if someone knew what they were doing I've a somewhat modified CHO head with Dreer K/W 6mm valves in factory dia. What may qualify it as modified, it had its ports cast and they were described as 'hogged out' compared to other 750 heads. I'm told this is early Combat hand ported at factory before casting refined. Ken Canaga has it now and itching to finish and get it out for more projects.
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Re: Head flow testing.

Postby rvich » Sat Feb 05, 2011 7:59 am

I have been modifying my head a few brain cells at a time for years. But that probably doesn't make it unique in this crowd.
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Re: Head flow testing.

Postby Bill G » Sun Feb 06, 2011 12:42 pm

Jim
I have a RH4 that T C's shop modified for hot street use in the late 70's. Is this the type of thing you are looking to test? Do the rockers need to come out too?
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Re: Head flow testing.

Postby comnoz » Sun Feb 06, 2011 1:17 pm

Bill, Yes I would love to see what TC was doing back then. The RH intake rocker would need to be removed along with the 3 studs at the head gasket surface. I can pull the rocker spindle if you don't have a puller. Jim
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Re: Head flow testing.

Postby Bill G » Sun Feb 06, 2011 1:35 pm

I'll send it out. Probably later this week or early next. I'll email you when its on its way. I am curious too.
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Re: Head flow testing.

Postby lcrken » Sun Feb 06, 2011 1:46 pm

Jim,

I have Stage 2 and Stage 3 Maney heads that I can send. I have a couple Axtell heads, but the standard one is on an engine, and the short stroke one is waiting for new seats and guides. If this is going to be a long term project, I can eventually get them to you. I also have one of the factory short stroke race heads on a 920 engine that I will eventually have apart, and could send to you then. Also a slightly cleaned up stock short stroke head that I can send as soon as I disassemble it.

Just a bare head with an intake valve, right?

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Re: Head flow testing.

Postby comnoz » Sun Feb 06, 2011 2:28 pm

lcrken wrote:Jim,

I have Stage 2 and Stage 3 Maney heads that I can send. I have a couple Axtell heads, but the standard one is on an engine, and the short stroke one is waiting for new seats and guides. If this is going to be a long term project, I can eventually get them to you. I also have one of the factory short stroke race heads on a 920 engine that I will eventually have apart, and could send to you then. Also a slightly cleaned up stock short stroke head that I can send as soon as I disassemble it.

Just a bare head with an intake valve, right?

Ken


Ken, I will keep doing this for as long as I can. I will just do the RH intake port unless I see something that catches my eye and want to do some more checking. I would need 1 intake valve and one exhaust valve. The rocker arm for the RH intake will need to come out so my valve lifter will fit. I will fit my own lightweight spring on that intake. Jim
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Re: Head flow testing.

Postby Rohan » Sun Feb 06, 2011 3:06 pm

Any chance of a pic or 2 of these short stroke heads ?
If they are not on the secret list....

Combustion chamber and down the ports shots could be interesting.
Are they far different, if at all, from roadgoing heads ?

I seem to recall the racers asking for a extra 1/2" height on the inlet valve side of things on new heads, if at all possile, to give more downdraft ports. So short stroke heads have this ??

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Re: Head flow testing.

Postby lcrken » Sun Feb 06, 2011 9:10 pm

Rohan wrote:Any chance of a pic or 2 of these short stroke heads ?
If they are not on the secret list....

Combustion chamber and down the ports shots could be interesting.
Are they far different, if at all, from roadgoing heads ?

I seem to recall the racers asking for a extra 1/2" height on the inlet valve side of things on new heads, if at all possile, to give more downdraft ports. So short stroke heads have this ??


I have some pics of the heads, but I'll try to take some better ones and post them later. The short stroke heads used the same castings as standard heads, and the intake ports were in the same location as standard. The main difference was valve size and combustion chamber shape. The factory changed the angle on the intakes from the stock 28 degrees from vertica to 26.5 degrees to let them fit larger intake valves. The production short stroke had had the same size exhaust valve as standard, but a larger 1.625" intake. The other change was to machine the combustion chamber to a full hemi shape with no squish bands. The intake and exhaust ports were the same as standard heads, except for the difference at short side radius and the seat to accomodate the larger intake. There was also a race kit head, but I don't have any info on it. The factory race heads had even larger intake valves, as well as larger exhaust valves. The one I have from one of the factory flat track racers has 1.696" intake and 1.370" exhaust, but it was modified by the race shop, so I don't think those are necessarily the sizes on the race kit heads.

This is a shot of the combusion chamber or a production RH7 short stroke head, but with non-stock black diamond valves fitted. This is the head from the 750 engine I ran in my featherbed racer at Bonneville.

Image

These are pictures of a short stroke head I got from Ron Wood. It had been modified by Axtell, and was from one of Ron's flat track bikes. It needed some repairs in the stud thread areas, and still needs new intake valve seats, which I plan to get to this year. The extra cooling fins were added by Ron and Axe. The valve guides and oil return fitting are also Axtell's, not factory. The spark plug and cylinder head inserts are also not factory. Valve sizes are very close to those in the factory race head I mentioned above.

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Re: Head flow testing.

Postby lcrken » Sun Feb 06, 2011 9:27 pm

I found one more. This is a pic of the head from the factory flat track racer. It's now on the 920 engine in our streamliner. I use a flat top piston with the 920, so you don't see the clean area that you see on the other heads, which are used on 750 engines where I use a dome on the piston that is carefully shaped to provide a squish area between it and the combustion chamber

Image

This pic shows the shape of the pistons for the 750 engines, and you can see the curved area on the side of the dome that provices the squish clearance.

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Re: Head flow testing.

Postby hobot » Mon Feb 07, 2011 2:22 pm

What is the thingagig under/between the intake ports?
The hemi dome piston squish bands have enough area to put in Singh Grooves, whether it'd matter or not.

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Re: Head flow testing.

Postby swooshdave » Mon Feb 07, 2011 4:31 pm

hobot wrote:What is the thingagig under/between the intake ports?
The hemi dome piston squish bands have enough area to put in Singh Grooves, whether it'd matter or not.


I bet it's a breather. Or extra oil drain, but I think a breather.
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Re: Head flow testing.

Postby comnoz » Mon Feb 07, 2011 4:56 pm

swooshdave wrote:
hobot wrote:What is the thingagig under/between the intake ports?
The hemi dome piston squish bands have enough area to put in Singh Grooves, whether it'd matter or not.


I bet it's a breather. Or extra oil drain, but I think a breather.


It is an oil drain. When the ports are enlarged that much you cut into the stock oil return and it must be blocked off. Jim
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Re: Head flow testing.

Postby lcrken » Mon Feb 07, 2011 5:07 pm

comnoz wrote:It is an oil drain. When the ports are enlarged that much you cut into the stock oil return and it must be blocked off. Jim


Correctamundo. Same sort of mods on some of the Maney heads. The other short stroke heads I posted pictures of don't need it because they kept the stock 32 mm port diameter.

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