High compression head

Tom Endy

Tom Endy

Well-known member
Many of you may be aware that most every supplier in the country is out of stock of Snyder 5.5 high compression heads. I checked with most of the better suppliers and I am hearing several month before new stock will be available. One engine builder in Illinois I spoke with was very disenchanted as he is not able to deliver a number of engines he has orders for and it is affecting his cash flow.

I have been told there is an old article around written by the secrets of speed folks that was written before high compression heads became a marketable item, that says you can take a stock head and mill off 5\32", and if you have a 60 over bore you will have close to a 5.5 head.

My question is: How do you tell if a head has ever been milled? There must be a measurement of the distance from the bottom of the head to the distributor boss for a stock unmolested head. Does anybody know what that measurement would be, and is the machined surface of the distributor boss a contstant measurement?

Tom Endy
 
Tom,
Stock head thickness is 2.25" measured at the distributor pass thru. I beilieve the piston reliefs were .080.
I just bought a used 5.5 from east coast......didn't know they are so scarce.
 
I got a Snyder 5.5 head about a week ago. You need to call and get on the list. When they get them they ship in the order of folks on their list.
 
Tom Endy said:
Many of you may be aware that most every supplier in the country is out of stock of Snyder 5.5 high compression heads. I checked with most of the better suppliers and I am hearing several month before new stock will be available. One engine builder in Illinois I spoke with was very disenchanted as he is not able to deliver a number of engines he has orders for and it is affecting his cash flow.

I have been told there is an old article around written by the secrets of speed folks that was written before high compression heads became a marketable item, that says you can take a stock head and mill off 5\32", and if you have a 60 over bore you will have close to a 5.5 head.

My question is: How do you tell if a head has ever been milled? There must be a measurement of the distance from the bottom of the head to the distributor boss for a stock unmolested head. Does anybody know what that measurement would be, and is the machined surface of the distributor boss a contstant measurement?

Tom Endy
Click to expand...

It is not worth the effort to mill a stock head that much. I have done it years ago when there were no H C heads available. The problem is combustion chamber shape
 
I measured a new later production head --has a diamond under the waterpump boss

thickness at stud bosses -and dist boss --2.234
depth of counterbore over piston --.115--.117
 
George Miller said:
It is not worth the effort to mill a stock head that much. I have done it years ago when there were no H C heads available. The problem is combustion chamber shape
Click to expand...
I agree, George. I have one I bought at Hershey years ago in my more ignorant days and found it to not have any more compression than a stock head. I might post some pics here tomorrow after I get back from the mountaineer show.
 
steve norcal said:
i have a 5.5 head with .060 milled off . 6-1 now .
Click to expand...

What did the chambers CC after milling? I would expect 159cc on average which would be 5.82:1 on a standard bore engine which is getting close.

Tom Endy said:
I have been told there is an old article around written by the secrets of speed folks that was written before high compression heads became a marketable item, that says you can take a stock head and mill off 5\32", and if you have a 60 over bore you will have close to a 5.5 head.
Click to expand...

The original unmilled heads I've checked had counterbores measuring .093" deep on average. I wouldn't run a head without a counterbore as it doesn't leave much clearance. The standard piston protrusion was .031" so if you had the block decked .009" the protrusion would be about .040"
 
Mitch//pa said:
is the snyders 5.5 head the same one that bratton sells ?? brattons calls theirs a police head
thanks
Click to expand...

Bratton's 5.5 head is a Snyder head. I believe Snyder is the only one making a high compression head. I don't think a Brumfield head is currently being marketed.

Tom Endy
 
You might try Red's Headers in CA. I got a 7:1 aluminum Winfield head from them not too long ago. They had both 6:1 and 7:1 at the time.
Dick
 
I spoke with Walt Bratton this morning. They are still out of stock of Snyder 5.5 heads. I am on their waiting list. From the responses to this post I don't think I will persue milling a stock head.

Walt tells me they had a recall on the Snyder 6.1 heads due to the distributor and lug bosses being too high.

Thanks to those that responded.
Tom Endy
 
i have a 5.5 i bought from brattons that i used for 500 miles and took it off. i dont want it anymore i guess ill list it on ebay unless someone wants it ......
 
I just received shipment of (3) 5.5 heads from Snyders late last week. James is correct on the waiting list. I have been on the same list for 3 months. The new production of the 6:1 should be arriving soon. I have been on that list for 3 months also.
Have a good weekend all!
 
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Tom Endy said:
I spoke with Walt Bratton this morning. They are still out of stock of Snyder 5.5 heads. I am on their waiting list. From the responses to this post I don't think I will persue milling a stock head.

Walt tells me they had a recall on the Snyder 6.1 heads due to the distributor and lug bosses being too high.

Thanks to those that responded.
Tom Endy
Click to expand...


Who do we contact for the recall?
 
, Why'd ya take a good HC head off? On the face of it, it seems wrong. You must have had a good reason.
Terry



Mitch//pa said:
i have a 5.5 i bought from brattons that i used for 500 miles and took it off. i dont want it anymore i guess ill list it on ebay unless someone wants it ......
Click to expand...
 
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