suggestions on 990 rect port heads

[68black_betty]

got a 454 bored .30 holley 750 dp with air gap intake and a mild rv cam. i found a set of ported 990 heads for what seems like great deal, but dont know much about them, i been researchin them a bit and am getting mixed reviews, i wanna try and hit 500 rwhp without breaking the bank. so anyone that knows their big blocks pretty well please help

[68_chop_top]

The 990 head is listed as Chevy's stock replacement iron rectangular-port head in the GM Performance Parts catalog but it is no longer available. These can make big hp but your listed components suggest a mild build. Using these heads with those combo will kill the bottom end grunt. What heads do you have now?

[68black_betty]

yeah right now its justa mild build but i wanna go up with it all. i wanna go with a bigger cam somethin with around a 110 or so lobe sep and around 650 lift, eventually im gonna throw in a stroker crank but for now what i wanna do is go with a bigger cam and maybe some new pistons to get a better compression. what reccomendation on heads for me would yours be, also what are the best pistons and cam to combine with them, i wanna get like a 11 to 1 compression or in that area

[68_chop_top]

11 to 1 is a bit much for the streets unless you can get rocket fuel. Lets try for less than 10 to 1. Speed Pro hyperuetic with 180 dome gets 9.6 to 1. Use Comp Cam XR282 hydraulic roller cam. Any small peanut port open chamber head will do for now. This set up with high rise aluminum intake, 750 carb, headers, and 2200 stall converter will make neck snapping 500 hp and tq.

[68black_betty]

sounds awesome man, beautiful truck btw, the heads i have on it now are the 236 heads, dont know much about them but i been lookin around for a set of 781 heads. do you think if i ported out the 236 heads it would be just as much bang for my buck as going with a set of 781 heads. Also you said that cam would be perfect for peanut port heads, would it make a difference with larger ported heads

[68black_betty]

also i would like to get your opinion on what is better a th400 tranny or the 700r4, i have the 400 in right now and a spare 700r4 with a lockout converter in the garage, thats a nother issue i been seein mioxed opinions on that as well

[68_chop_top]

781 AND 236 are almost identical heads. Better money would be larger valves 2.18 Intake and 1.88 Exhaust. Dont worry about porting the heads. Make sure the intake matches the head port style, oval to oval and rect to rect.
Personally I like the 700R4 for the overdrive and mpg. Dont worry about mpg when you drive a big block. One may be stronger than the other but I dont know that much.

[68black_betty]

wouldnt you have to put the port the heads though for larger valves. also for the pistons and cam, in your opinion where would i get the better deals on those, some sites have the cam for like 500 others have it for under 300 and im havin trouble finding those pistons you were talking about. the reason i wanna go with better heads is cause i intend oon strokin sometime down the road

[68_chop_top]

I replied to your PM

[LJ534Rat]

The 990 head is more for a high comp. high RPM motor.The 781 or 049 are a ovalport 119 cc head and would be a much better choice. And should make lots of torque compared to the 990 head. Would be better to stay around 600 lift or you will be having piston/valve clearance problems. A Speedpro L2465 forged (for any nitrous use in the future) with a 119cc chamber 781 would be @ 9.6 ish on the comp. A Comp solid w/248/.248 @ 050 and .595/.595 lift would work fine.I had a similar combo in a 72 SWB and ran 11.70 @ 118 on motor.

[chris mc bride]

IMO I would go with larger valves, good pocket porting,3 or 5 angle valve job,270 or 282 cam. I like the oval port heads for street especaily if plan to tow anything with it.I agree about kepping the compression down to 10:1 or close to it. I would use quality set of headers with 2 3/4 duals and good flowing mufflers.
Remember thers lots of places to get free(gas wise not money) horsepower. I almost always try to use elctric fans,coldair induction system and mostimpotantly tune it right. No matter how good the parts or how much money you spend you will not see the true protential w/o good tuning. I don't any reason you should have problem reaching 500 hp.
A side note I saw where you plan on stepping power up lil at a time. After years of playing with motors I can tell you its almost always cheaper to decide on goal and buy parts along then put it all together at one time. Case in point buying pistons now then buying another set if you go bigger with crank would mean money for new pistons is gone.You could have stepped up to hyd roller cam or got to goal sooner. Just my experiance and my opion