Head flow testing.

The Sandy Bandit (Cliff Majhor) would often say that Dick Mann could win a motorcycle race on a pogo stick.[/quote]

I don't find that hard to believe. He definitely gave me a riding lesson.

Well I did a full competition port job on a Fullauto head today. Stock valves and 30mm port area. Reworked the bowl and guide area.
The light green line is the Maney stage three. Huge everywhere.
The dark green line is the Maney stage 2 with 1.615 valve and 33 mm port ,
The blue line is the fullauto with stock 1.5 valve and 30 mm port
The yellow line is the out of the box Fullauto.
The port velocity on the modified Fullauto is almost double the Maney stage 2.



Interesting phenomena- a MAP 36 mm manifold flows 10 cfm more when the manifold is moved to the left 1/2 bolt hole than it does when the bores are matched. Wild turbulence going on there.

Interesting phenomena- a MAP 36 mm manifold flows 10 cfm more when the manifold is moved to the left 1/2 bolt hole than it does when the bores are matched. Wild turbulence going on there.

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Ms Peel had a lip in 32 mm manifold mating to 30 mm head plus intruding crude gasket. I attribute a significant part of Peels spunk to this trip up and plan to experiment with it again on factory Combat Trixie. I also attribute extra spunk to the smaller faster ports than CHO head. This touches on Viktor Schauberger turbulent flow discoveries. Keep playing and may discover more.
http://discaircraft.greyfalcon.us/Vikto ... berger.htm

Really old school wonder to contrast with today.
To the Nth degree SV head details and way more.
http://rapidhare.blogspot.com/search/label/-Technical

Flowed a couple more heads this evening.
I did a nice stock RH4 and a stage 2 modified head by a well known tuner.
The modified head started life as an RH10 and has stock valves and 35mm ports. Here is what it looked like.



Here is the graph, and yes I flowed it multiple times because I though there must be something wrong.
The green line is the big port modified head.
The yellow line is the stock RH4
The red line is a competition flowed fullauto with stock valves
The blue line is a ported fullauto with .060 oversize intake - it's going on my bike
The white line is the Maney stage two with .115 oversize intake valve and 35mm port



And here is the velocity graph
The blue line is the competition Fullauto
The blue-green line is the stock head
The red line is the Maney stage 2
The green line is the stage 2 that I just tested. Glad I didn't buy it.

So you've tested a few heads now, what are your recommendations for:

Regular street
Fast Street
Racing

If you say Full Auto for all three we know you're biased. :mrgreen:

swooshdave said:

So you've tested a few heads now, what are your recommendations for:

Regular street
Fast Street
Racing

If you say Full Auto for all three we know you're biased. :mrgreen:

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No I would say a Maney stage 3 unless you are under 1000cc. Then I like the Fullauto more all the time. Of course I could be biased. :wink:

Hi Comnoz,
the green big port modified head has the big valve guides inside, so far I know has the fullaouto ½ inch valve guides.
I never saw the intake of the fullauto, maybe you can post a pic ? THANKS!
Christian

Christian said:

Hi Comnoz,
the green big port modified head has the big valve guides inside, so far I know has the fullaouto ½ inch valve guides.
I never saw the intake of the fullauto, maybe you can post a pic ? THANKS!
Christian

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Here are some pictures of the ports on the fullauto head. It's hard to show the shape of the port very well.

What sort of valve shapes have been tested as flowing best. I remember hearing that Axtell preferred nail-head valves and not tulip shaped ones in his Norton heads.....

Norton heads do not flow well with tuliped valves. They are designed for heads with more downdaft in the port. Kibblewhite valves will outflow the stock Norton valves. Jim

Jim, are you interested in in a Dreer / Baisley 880 head? I've got one sitting on the shelf. I can pull the valves, it has no rockers or studs installed yet.

[quote="grandpaul"]Jim, are you interested in in a Dreer / Baisley 880 head? I've got one sitting on the shelf. I can pull the valves, it has no rockers or studs installed yet.[/quote]



Yes I would be very interested. Jim

beng said:

What sort of valve shapes have been tested as flowing best. I remember hearing that Axtell preferred nail-head valves and not tulip shaped ones in his Norton heads.....

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Yep. Back in the '70s when he did a couple 750 heads for me he used nail-head valves that he made from Ford Falcon valves. I'm not sure what he used for blanks later when he was working with the RH7 big valve heads, but they were also nail-head design.

Ken

Quote =Interesting phenomena- a MAP 36 mm manifold flows 10 cfm more when the manifold is moved to the left 1/2 bolt hole than it does when the bores are matched. Wild turbulence going on there. unquote

Very strange indeed.
Might I suggest, as you have access to a flow rig, to compare running with a straight tube and a tube with an ‘S ‘ bend in it to see how they compare as to which is the better at gas flow. I wouldn’t like to put my money on which would be better.

Bernhard said:

Quote =Interesting phenomena- a MAP 36 mm manifold flows 10 cfm more when the manifold is moved to the left 1/2 bolt hole than it does when the bores are matched. Wild turbulence going on there. unquote

Very strange indeed.
Might I suggest, as you have access to a flow rig, to compare running with a straight tube and a tube with an ‘S ‘ bend in it to see how they compare as to which is the better at gas flow. I wouldn’t like to put my money on which would be better.

Click to expand...

Fast moving air does not like to change direction. A straight tube with no obstructions will win every time. About the only thing worse than an S bend would be a W bend. Jim

Short, fat, and straight.

Kinda like me!!! lol lol Well 5' 8" :lol:

Here is a port mold I took a long time ago of an 32mm RH4 head from a early 73' 850 Commando, one of those with the silver cylinder barrels. It really looks like shit, notice how the port droops down like it has a beer belly then goes back up to get to the valve pocket. A real POS. I would never pay any money for a factory Combat or RH4 head. It has already been said, the standard Commando head and the RH10 850 head would be better bets for any application at all. The RH10 tapered intake manifolds and 32mm Concentrics bolted onto any of the small port Commando heads is probably the best factory parts-bin bolt-together combination you will find.



Below is a mold taken from a 1962 650ss head. These heads had small valve bowls or pockets, but they sure had a nice shape. The downdraught Norton twin head was first put on the 650 Manxman in late 1960, used on the Domiracer in 1961 and then on the 1962 88ss and 650ss. At the end of 1962 the Bracebridge Street works was closed and production was moved to the AMC works and many detail changes were made in the bikes and their engines, most of them in the interest of speeding up production and cutting costs. The old Bracebridge street heads may not have had the highest overall flow but looking at the port mold they sure look nicely done and would be good raw material for a port job....

Can you tell us what top end you get on a track , unstreamlined , out of the 750s , or Mc Rae's at Daytona , mph , or rpms / gearing . :?: please . :| i.e. whats been obtained , obviously not std .