i got this from
www.bluethunderauto.com
"BLUE THUNDER FORD SMALL BLOCK RACE ONLY CYLINDER HEAD
This head is a canted valve (351C valve angles and location) Yates intake port location head that can use 2.02" to
2.20" intake valves and 1.60" to 1.70" exhaust valves. 7Occ and 50cc combustion chambers are available. Two
different exhaust ports are available. The high exhaust port is Yates bolt pattern and height. The low exhaust port
has a double Cleveland bolt pattern. The lower bolt pattern is stock Cleveland height with a port that functions as a
"stuffed Cleveland" port, in which the bottom of the port is filled. The second bolt pattern is .750" higher and
aligns the floor of the port with floor of the flange. The top of the port can then be cut out to match the flange for
increased exhaust flow.
All ports have .400" wall on them. This head has partly machined alcohol down nozzles that can be finished with
careful use of a hand held drill.
Manifolds for the head are available from both Ford Motorsport and Edelbrock."