LS-7 #990 head

[RichSchmidt]

The 990 head is a rectangular port open chamber head that was offered on LS6 crate engines.I dont think it was ever offered on a production car,but it is a very popular perfromance head for drag racers on a budget.It has since been replaced with the #088 head which I believe is Gen V and Gen VI compatable,but dont hold me to that.The 990 head is similar to the #188 head which was the first design LS6 crate motor head.
As far as I know the real 1970 LS6 with 10.25:1 in a production car was a closed chamber engine. LS6 crate motors had the same compression but with open chamber heads.An LS7 has pistons that were designed to give about 12:1 compression with open chamber heads.An LS7 was only available as a shortblock,but was cheaper then an LS6 long block,and had higher compression pistons,and a bigger cam,and was basically like a 454 version of the L88.A budget racer would top the LS7 off with 990 heads which were cheap back in the day and add a tunnel ram and some other tricks and make an honest 575hp 454.A better funded racer would have added the extra $200 or so to the budget and went for some 074 casting aluminum heads.
The #990 head is a great peice for a 454 buildup,but inst correct for any car that I know of,but maybe a 71 HI-PO 454 with open chamber heads.But dont hold me to that.