Thomas head marked 8???
 

Does this seem right? I got this Thomas head with a bunch of model a parts... I am concidering putting it on my ‘31 roadster project. Does this number mean it’s 8:1 compression? Any help greatly appreciated

Re: Thomas head marked 8???
 

Re: Thomas head marked 8???
 

Photos of the chamber might be informative...

Re: Thomas head marked 8???
 

How about a picture of the combustion chamber? Maybe "8" was the inspector's stamp. Attached is photo you might enjoy, unfortunately it is not my engine.

Charlie Stephens

Re: Thomas head marked 8???
 

Good looking engine, air scoops on backward.

Re: Thomas head marked 8???
 

Here is a pic of combustion chamber, I did find on Model A Ford garage a cc to compression ratio graph.

Re: Thomas head marked 8???
 

My Thomas head is a 7-1. I don't think there is an 8-1 Thomas. But maybe????

Re: Thomas head marked 8???
 

Probably the 8th casting in that batch of pours. My super Winfield is stamped 108, for 108th casting.

Re: Thomas head marked 8???
 

I'm guessing 6.1 cr, from pictures of chamber.

Re: Thomas head marked 8???
 

That's different from the Thomas head I have. Completely different chambers and the plugs are on the edge of the bores on mine. Not sure if I have any photos.

Re: Thomas head marked 8???
 

Well, I checked cc’s yesterday with Home made tools. Got approx 160cc, no head gasket. Will need to compare to graph. The bore is .060 over. Spark plug hole are 14 mm, this head was sitting in a storage locker for past 30 years.