Thread: Open or closed chambered ????? Help

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This site says open chamber ?????

Originally Posted by glennsexton

I believe the 3975950 heads are from 1968-70 366T, 396, 402, and 427 truck engines. It has 2.06/1.77 valves and closed chamber oval ports. I don't remember if I have never seen this particular casting number, but all credible sources say that it's an oval port, closed chamber head. Check this web site for more details:

http://www.chevcarclubvic.org.au/tec...ng_numbers.htm

Regards,
Glenn

Must be my eyes! You are correct. I checked a few other sites and these are OPEN Chamber heads.. However -

http://www.nastyz28.com/bbcmenu.php - says they're closed
http://www.novas.net/forums/showthread.php?t=4334 - says they're closed

Take a picture of the bottom of the head and post.

Take a picture of the bottom of the head and post.[/QUOTE] thats a good idea i can not remember all the casting numbers for all the gm bbc heads are they like the 929 cast like in my photo ? this head was used on alot of the 402 the 396 used a closed chamber we called them bath tub heads like 65to67. then i think in 68 to69 they trim more off above the spark plug then went to the 929 type chamber