Champion 185 deck height--compression

[Dan Ward]

Hello----Does anyone know what the deck height was on the champion 185 flathead--originally?
( The distance from the block down to the piston when the piston is all the way up).
I am doing a total rebuild and when I run the numbers, the compression is coming out way high--like 10.2 to one. The book says it was 7.5 or 8 to one when built at the factory. I was hoping for about 9 to one.

Are there any disadvantages to a 10 to one compression other than maybe having to run high octane gas?
I've been told the pluses include better gas milage and more horsepower.

The deck has already been cut, so the only way to reduce the compression now would be to machine out the cavities in the head or maybe have a head gasket made at much expense.

I'm by no means an expert on this so please let me know your thoughts---Regards Dan

[PackardV8]

Hi, Dan,

Yes, there are major disadvantages. A flathead will give serious pinging problems, overheating and loss of power at anything much more than 8.5-1.
No, I can't imagine you've really got that much compression. Have you carefully measured the head volume and then used this calculator which includes the gasket thickness and all the little spaces? http://www.kb-silvolite.com/calc.php?action=comp
Maybe, you can add some volume by relieving the block. http://www.flatheadv8.org/bishop/porting1.htm

thnx, jack vines

[raoul5788]

Hello----Does anyone know what the deck height was on the champion 185 flathead--originally?
( The distance from the block down to the piston when the piston is all the way up).
I am doing a total rebuild and when I run the numbers, the compression is coming out way high--like 10.2 to one. The book says it was 7.5 or 8 to one when built at the factory. I was hoping for about 9 to one.

Are there any disadvantages to a 10 to one compression other than maybe having to run high octane gas?
I've been told the pluses include better gas milage and more horsepower.

The deck has already been cut, so the only way to reduce the compression now would be to machine out the cavities in the head or maybe have a head gasket made at much expense.

I'm by no means an expert on this so please let me know your thoughts---Regards Dan

You may want to contact Bill Cathcart for his ideas. He can be reached at 860-564-5852.

[Dan Ward]

Thanks to all!

Chip----I did talk to Bill Cathcart. He was very helpful

Jack---It looks as if my calculations are correct. I need to find out the exact volume of an original head to make sure. The head I have has to have too small a volume. Regards Dan