Model A head combustion chamber shape

tjw

tjw

Senior Member
An old Model A alloy head I came across with an interesting combustion chamber design. Good, bad, otherwise, any one got any comments on its design / performance.
 

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I like it a lot.
Who made it?
Looks like an excellent way to get some reasonable flow & a bit of compression
 
I know very little about it other that it may have been made in Australia and by whom I do not know as there is no brand name on it.
 
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To me,it appears that someone knew what he was doing.
I'd fix whatever needs to be fixed & run that thing. I think
it would out-perform any other Model A/B flathead.
What's the other side look like?
Jim
 
That is a good design as it allows good flow between the intake valve and the cyl. The late Harley-Davidson, as well as Indian and even Briggs & Stratton used a similar design, as well as my new heads. A guy named Jerry Silberstein also made a similar head here in CA, built as a replacement head for A's, it looked like a stock head on the outside and ran very well. Yours looks like it has been run, and I think has enough water passages to do the deed.
 
Probably made for speedway.

I've got an alloy head with more standard chamber, and no water pump provision, just a hose pipe at the front. Local made.

I still have some parts I was given as a kid by a guy who speedway raced a Model A.

I've only been to the speedway once. It was in Broome, Western Australia (out in the sticks).
The camp ground was next to the speedway. It was so noisy in the camp ground we decided to join them.
We met up with the guys that had serviced our car that day. There was a lot of beer and noise involved, I remember that.
 
Could you please show the other side. Is this a two piece head?
It could be a Norm "Frick" or Robert "Roof" head if a 2 pc. . . .Or as you think made in Australia or New Zealand

A "R&R" (Robert Roof) 2 pc was sold on Ebay about 5 years ago for $4500.00. Go figure.

The "turbulence" chamber stepping design has been tried since Bangers were invented. Whether it actually works (facts/tests) or not on a four banger Model A, B, T has not been published to my knowledge. It may have an effect but who knows? Some of these "shapes" do not hold up well on a dyno compared to the basic "Ricardo" one step chambers (think Winfield heads).
What I mean by that is all things compared, chamber volume (compression ratio) and flame front are really the deciding factors. Heavy thick walled castings also hold heat steady and help a lot toward smooth operation.

Dennis Piranio has run the Donovon Model "D" flathead (heavily modified) at Bonneville and I believe it has the two steps and he might be able to share his Dyno results and thoughts.

I have to add because J.B. did: My iron and aluminum Lion Speed Head have a single stepped Ricardo version and dyno at the upper ends of 113 HP and excellent torque at 7:1 CR at 3200 rpm and of course the spark plugs are over the pistons for a superior flame front.
 
"My iron and aluminum Lion Speed Head have a single stepped Ricardo version and dyno at the upper ends of 113 HP and excellent torque at 7:1 CR at 3200 rpm".

Now that is impressive at only 3200 rpm. WOW. 113 HP @ 3200?
I'd love to know the rest of the engine combination?
Jim
 
Kahuna said:
To me,it appears that someone knew what he was doing.
I'd fix whatever needs to be fixed & run that thing. I think
it would out-perform any other Model A/B flathead.
What's the other side look like?
Jim
Click to expand...
Jim
I will take some photos of the top and also the inside of the head for you. It is a two piece head.
 
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