LS-7 #990 head

[COPO_Anders]

I have been offered a "new" head that supposedly came off an LS-7 crate engine back in the day. This guy says that these #990 heads were taken off and aluminum heads were added instead.

Has anyone heard of a cast ironhead with the last three digits 990 ?

Didn´t the LS-7 crate engines come with aluminum heads ?

Anders

[SuperNovaSS]

Yes, the 990 head is a 454 rectangular port closed chamber replacement offered over the counter in the 70s. Since the LS7 was a crate engine I imagine it could be ordered with this head or an aluminum.


Jason

[COPO_Anders]

Thank´s Jason, I couldn´t find it in any of my books.



Anders

[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.

[COPO_Anders]

When you mentioned the #188 head I became confused. I´ll explain why:
I have a brand new 1989 crate LS-6 engine. At least that´s what I think it is.
It´s got a #14015445 4-bolt main block with forged crank and 7/16" dimple rods. The dome on the #3999295 pistons seems to be to small mabye for an LS-6 engine. The HEADS are #14096188 castings, with is a rectangular port open chamber head. It has 3/8" guideplates and of course 3/8" pushrods. This engine has also the LS-6 cam in it. I have always considered it to be a -71 version LS-6, that is with lower compression than the -70 LS-6. It had never been started when I took it apart to inspect it. The engine is stamped T05179XF. It has the same trap-door oilpan as the new ZL-1 crate engines.

1.Is there a #39XX188 head as well as the later #14096188 head ?

2. In which applications was the #3999295 piston used ?

Anders

[RichSchmidt]

It funny that you mention that,because I always thought that the 188 head was the later 990 head,but I went on to Mortec while I was posting yesterday to see if they showed the 188 head as being gen V or VI compatable and it showed the 188 head as the early head and the 088 head as the later one.so thats what I posted,but maybe I should have followed my gut on this one.I have a GMPP book from the late 90's that I can check sometime next week,but I was pretty sure it has the new 990 head as being the 188 head.You engine sounds like a 9.25:1 454,and I like to use that combo for street/strip engines,I call it the 2399 shortblock in reference to the TRW number for those pistons.One of my secret street combos is the GMPP 110 cc roval head on a zero deck 461 with those pistons,and it is a setup that spanks all the 502's around town.The LS6 pistons have another good feature,and that is that the dome isnt too big on the exhaust side of the chamber,so you can still run a fairly stout cam even if you whack the 118cc heads to get more compression.With the cam you claim to have you could whack those heads .040" and zero deck the block at the next rebuild and have close to 10:1.The #445 block isnt a "true" LS6 block in the sense that it isnt one of the notoriously thick castings,but it will serve you well up to .060" overbore,and some can go a bit more.The hot LS6 crate to have was the mid 70's#289 blocks,and they would bore way out there.By the late 80's,the LS6 crate motor was just a stepping stone to the 454HO crate motor that was to come,but it is still a great street peice.I will let you know if I find the information I was loking for on those heads.

[COPO_Anders]

Great information so far Rich. Looking forward to any further information you might find.



Anders

[Stefano]

990s are correct for some late Motion Performance Built cars.