where are the numbers and which heads are better

 

Check out Mummert's web site, www.ford-y-block.com. He has a page that describes where to find the ID and what CR they are.

The ECZ-C heads have their ID between exhaust ports. Other heads have them on the underside of the water ports on the intake surface of the heads. Some heads, like the C3TE heads have them under the valve covers.

The C1 and C3 heads are ok, but not high performance. The heads with the biggest ports and valves and the smallest chambers are the ECZ-G and the -113. Y-guys will seek out the ECZ-C for F100's because they have chambers that are small enough to get good compression, and valves big enough to work. If you've got a honking stroker 312/342 you might want the 471 or ECZ-B to get the compression ratio down to a reasonable level.

 

ok going by that I seem to have some 471's thatI pulled off this $100 y-block I bought for parts. The block cast # is B9AE is there a way to be sure this is a 292 and not a 312. And going by your info the 471's are not the ideal head for a stock rebuild?

 

mummerts site will show how to tell a 292 from 312.471s are low comp,.

 

IIRC, there were three big valve heads; ECZ-G, -113 and -471. The heads you have won't make the most compression, but they do have the big valves.

 

Depending on if these are posted heads (I think so) they can be milled to increase compression.

 

Posted can be milled .045. Non posted .025. If stock compressions are run, it isnt worth worrying about over posted/nonposted. For each .0055 milled figure 1 cc reduction in combustion chamber volume.

 

well turns out the heads on my motor thats still in the truck are the 113's so I think I will be rebuilding them. I guess this would be a good time to have them reseated for unleaded gas so I can stop running lead additive.

 

That is good news. Some think the 113s are the best of the bunch.