I'm looking at used injections. I have an old cast iron stock chevy motor.Can someone clarify 23 degree headed injection, raised port injection, injection for -12 headed motor....etc. what is a 23 degree, raised port or -12 head? And where are the differences actually found or located? I'm old school and regretfully never progressed with the times. Hope my questions make sense. Lots of knowledge on the board. thanks for any help or clarification. rc

I can't answer your questions but you may be able to learn something from Brodix and Kinsler's websites
http://www.brodix.com/heads/small-bl...mpatible-heads

http://www.kinsler.com/index.php/handbook-catalog

Stock small block chevy heads have a 23 degree valve angle unless they've been angle milled. -12 heads are a series of heads with a 15 degree valve angle made by Brodix and sometimes used on sprint cars. Raised port heads are just that, aftermarket heads that have the ports raised relative to stock heads. If you have stock sbc heads you'll need 23 degree injection of some sort, but I'd call the manufacturers tech people and pick their brain.