can anyone tell me what size chambers are the
990 rec port heads

looking for 10.00-1 to 10.25-1
speed pro offers an ls6 replacement piston with
an .095 dome and no valve reliefs #2399f

going in a ls7 crate moter--was 12.5-1

any suggestions would be appreciated

Mortec says they're 118cc's, but that's probably just an average of those heads, they might cc to be different depending on what they've been through (head work, etc).

Speed Pro lists a L2465F that'd probably be a little closer to your target. The 2399 might come in a little low with that small dome and 118cc chamber in the 990 head. Plus, it's cheaper that the L2399. It does use a pressed pin, though.

Randy

My '74 castings cc'd to 115, but they have been surfaced at least once that I know of. I had .008" cut off.

I hope you can get a cam to make those heads work, can you say lazy acceleration,way too much port for that compression.

the cam i plan on using is a lunati hyd.
#lun00026
232/239 @ .050 549-558 lift
110 c/l

400 turbo w/3000 stall 3.73 gears

Almost the specs of my old solid cam, I'm guessing you might run within 2-3 tenths of mine if you can get it to hook,then again I might be totally suprised and you'll blow me away.

rapid robert--

do u think that 10.25-1 is pushing it for pump gas
or could i maybe get away with a little more

thanks for your reply

I was running 10.5-1 with open chamber oval ports, initial timing at 16* 20 more in by 2500 with no problems, ran 93 on the street and added 5 gallons of 110 at the track. I also had no vacuum advance.

I wouldn't worry too much about those heads being to big unless you're looking for every last .10. My old engine setup had rectangle port heads with 310cc runners and 119cc chamber. Compression was 10.37:1. Performance in signature. My heads are aluminum and pump gas (even low octane) was a non issue.

stick with the 2399's. 2465 is a piece of cr@p. It has no piston to valve clearance.after a flycut its cost is more than a good piston 2399,srp,kb etc.. been there done that.

thanks for all the input guys--hopefully will be making noise in a few weeks..

thanks again,

mike