New 5.5:1 Cylinder Head Availability

BButturff

BButturff

Senior Member
When I bought my Model A eighteen months ago I had no idea what cylinder head it had so I wasn't looking to buy one. But I remember them being readily available at Snyder's, Mike's, Bert's, Model A Medic, etc. So now that I know I have a stock head and I'm looking for a 5.5:1 head they've been "temporarily out of stock" for many months.


Anybody out there have an idea why this is? Are they no longer being produced?
 
Check with your favorite local machine shop and inquire as to having your head milled to your specifications.
 
You can't mill an A head to gain anything.The high-compression head has a whole different combustion chamber design.Some call it a heart shaped design.I don't have any pictures,but folks on here have posted the stock and high compression designs side by side.
 
Keith True said:
You can't mill an A head to gain anything.The high-compression head has a whole different combustion chamber design.Some call it a heart shaped design.I don't have any pictures,but folks on here have posted the stock and high compression designs side by side.
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Good to know. I went the mill route with my V8 heads, and it worked great, but the A head is another animal. Thanks for the clarification.
 
If you have an interest in a high compression head, contact Terry Burtz since he has a very good one available and I believe they are in stock. burtzblock.com


Frank
 
If you were considering a 5.5:1 head, a 6:1 head will not be much different. You would have a little more grunt at the bottom end of the rev range but that is about it. Just make sure you reduce the amount of ignition advance - too much is what kills bearings (and other things in there)
 
I put a Burtz head on and I am very impressed; my engine is .100 over. I also installed an automatic advance in the valve chamber. Limit my total advance to about 25-26 deg. engine runs great, plenty of power. Make sure your main and rod bearings are adjusted. I have a couple stock heads, and they are just dust collectors now.
 
Y-Blockhead said:
I see Snyder's has the 6.0 in stock. Maybe they are phasing out the 5.5 since they are almost the same CR and I believe made by the same person.

https://www.snydersantiqueauto.com/product.htm?pid=978622&cat=41686
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No. Snyder's makes both heads, they will keep selling both.

They make them in batches. You have to wait for the time for casting, transportation, machining, etc. They will be back in stock eventually.

I recommend the 5.5 over the 6.0 head for the average driver with average original engine. It is very easy to get engine knock with the 6.0 head, and then your bearings will go south.
 
Jim/GA said:
I recommend the 5.5 over the 6.0 head for the average driver with average original engine. It is very easy to get engine knock with the 6.0 head, and then your bearings will go south.
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I have heard or read this exact thing before. Although my engine was rebuilt fairly recently I don't know if it still has babbitt bearings or if it has been converted to insert bearings. Unfortunately, the family of the previous owner was no help in answering this question. My engine starts, idles and runs very well so I'm not yet willing to open it up just to find out.
 
BButturff said:
I have heard or read this exact thing before. Although my engine was rebuilt fairly recently I don't know if it still has babbitt bearings or if it has been converted to insert bearings.
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Why would that make a difference in this context?
 
alexiskai said:
Why would that make a difference in this context?
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Since there were valid suggestions of using a Snyder's 6.0 head or even the Burtz 6.5 head I felt compelled to explain why I don't consider them to be an option at this time. If and when I pull the pan off of my engine and discover insert bearings I would consider them.
 
BButturff said:
Since there were valid suggestions of using a Snyder's 6.0 head or even the Burtz 6.5 head I felt compelled to explain why I don't consider them to be an option at this time. If and when I pull the pan off of my engine and discover insert bearings I would consider them.
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The idea that Babbitt bearings can’t handle higher compression is a myth.
 
alexiskai said:
The idea that Babbitt bearings can’t handle higher compression is a myth.
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If it really is a myth I would appreciate any and all evidence to prove it so. Until then I can't take a chance on a Model A that I'll be handing down to my grandson some day.
 
Babbitt can’t handle high compression ??? Tell that to diesel engines that have babbitt bearings ! way more compression than a measly little 6.0 6.5 7.0 compression
 
I have been running 5.5:1 and 6:1 compression ratio cylinder heads for many years successfully with Babbitt bearings. By the way, the bearing diameter determines the amount of bearing stress in the Babbitt due to cylinder combustion pressures and inertial forces.
It makes good business sense if the 5.5:1 head was discontinued because of the 6:1 head. The difference between them is only 3%.
 
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