HarleyTechTalk

A friend of mine stumbled across a old set of flat heads.   One head appeared to be a high compression head.   After cc'ing them it turns out  they are the same.   Does anyone know what they would have originally measured from the factory?    Sorry for my lack of knowledge... I'm a toolmaker by trade not a wrench.   But trying to learn.   

Thanks for any help. 

Are there any stampings on the side of the heads?
'5' = it was low compression 5.0:1 when new
'6' = it was high compression 5.6:1 when new

Meanwhile, someone may well have skimmed an original 5 head to be a 6 head.
I don't think I have ever seen the actual cc figure for the heads mentioned anywhere - not even in the Victory Library series of 45 pamphlets.
I need to tidy up my library, and I need to do it fairly soon so I can find all the info I know I have somewhere to start ordering the parts to finish the rebuild on my 45.
That just might turn up the figures you need.

After an hour of tidying up my library I find the Victory Library 45 pamphlets - go and buy them - well worth it.
The factory #5 heads had about 0.120" milled from the gasket surface to make the #6 head.
#5 heads should not have more than 0.150" milled off them, #6 heads should not have more than 0.030" milled from them.
So far I have not found anything that would help either of us to work out if the heads we have have been milled in the past!

The Victory Library pamphlets do give the complete combustion chamber volume, but that is the heads plus the cylinder reliefs, cylinder bore, head gasket, modified piston etc.
So, not a lot of help then really...

Good information.   I'll see if I can find some of the 45 pamphlets.    It appears after getting them cleaned up that they are untouched.   [emoji106]
Thanks for the help PC!