I have an LG4 in my '85 Z28 with 148,000 miles and was considering some upgrades for it. I have Edelbrock headers and a high flow exhaust now to help it breathe along with an accel cap and rotor. I want to tear the motor down and install vortec heads, a cam and maybe a new intake. Will a new intake be necessary with the heads? Will a new manifold allow my carb to clear the stock hoodline? I'm using a dual snorkel cleaner too. Can these mods get me at least 50+ HP? I need to keep all pollution and computer because I live in NY. Will my Computer get fried? Please advise.

thanks for any input!

 

well, since you have the exhaust taken care of, there are two problems you face. crappy *** 305 heads, and the peanut sixzed lg4 cam. if you replace the two, put a performaer intake on, i would say you could easily gain 50 or more hp, and still clear the hood. the only thing is- thats a lot of miles, i have 160 on my lg4 and i decided the money i have had saved up for motor work would be better off paying off insurance for the year.. that way its like having a 200 dollar a month raise each month!

anyhow, i want to make my driveliine beefy before i throw a 400 horse 350 in it

Steve

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86 Firebird, LG4, t-tops, 2.73 open rear, SLP 3 inch cat back exhaust, catco cat, Coming mods: GOT A 350 IN THE WORKS BABY! gonna throw my TES edlebrock headers on it, and hopefully get some more gear and the cowl hood on

My Webpage- Battle of the birds, My own Thirdgen Page, still under construction, http://www.geocities.com/soares711/index.htm

88 Firebird Formula- deseased 2/9/99- 305 TPI, SLP 3 inch exhaust, SLP Intake runners, SLP cam, 3.45 BW disc brake posi, WS6, NOS, and all that good stuff, 13.8 on the motor, 12.89 on NOS and slicks! Hit by what else!?!? a FORD EXPLORER!!!!!!

 

The Vortec heads have larger chambers, so your compression will be lowered. And, you need a special Vortec EGR intake. I haven't heard of hood clearance problems with that combo, though.

A better bet would be to spend a few $'s more and get World 305 S/R Torquers. You'll keep your compression up and the engine will breathe much better than it does now. Be sure to follow up with the cam replacement. You can keep your LG4 manifold, perhaps gasket match it, or go with a Performer or Action +.

Your computer will be fine, but a chip may help improve the timing curve. I'm working with an '86 computer, and have heard something about it being different, so I'm not sure about that recommendation for an '85. It helped mine, though.

Is your baseline for a 50 HP increase stock, or with the improvements you have now? Over stock, no doubt, but you'll probably get 50 more than you have now with those changes.

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82 Berlinetta, orig V-6 car. Rescued w/86 LG4/TH700R with all harnesses, sensors, ECM, etc. 2.73 open, cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LB9 w/ZZ3 cam, ported heads, exhaust, paint, etc.).
57 Bel Air, my 1st car. Currently 396 .030 over, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.