I have a 1986 Z28 that I just put a 75 4bolt main 350 Bored .040 over in the car. It has an old set of double hump heads I'm not shure of the casting numbers, but they were of a 325 or 350hp 327. They have 1.94 intake valves, 1.60 exaust valves and 62cc combustion cambers. The motor has four valve relife flat top in it. It has a mellings cam 114 degers lsa, .450 intake lift, .461 exaust lift, 224 intake duration and 224 exaust duration. It also has a eblebrock preformer intake and a 600cfm preformer carb. The car is a 5 speed (t-5), with 3.73 in the rearend. The motor just isn't making the kind of power I wan't. The motor has about 3,000 miles on it. Does anyone have any suggestions on how I could get somemore horsepower out of this setup. I really don,t wan't to change heads I have to much money ivested in them. Woud a cam change help? Any feedback on how I could squeze some more power out of this setup would be greatly apperciated. I would like to make at least 350-400 horsepower.

 

Well thats not a hp combination of parts. The heads are really limiting your potential. Then you are using a small intake and a very old style cam.

I'd just get a new intake. A new cam isn't really gonna help with those heads.

 

yeah you have a lot of parts not designed to make any power. the heads are 40 years old or close to it, there are a lot of better heads made since those were new.

 

When you say it "isn't making the power you want" does that mean you're not running 12s yet or does that mean you can't outrun a Geo Metro?

That combo should be good for at least running somewhere in the 14s, maybe even high 13s with traction.

Is it running to it's potential but you want more? Or is it simply not running anywhere near as fast as it should?

 

That's a TERRIBLE cam. Probably the one thing most limiting your setup.

The intake is barely better than stock.

Conspicuous by its absence, is any mention of exhaust. If you're running original LG4 exhaust stuff, ANY OF IT, then that's probably where all your HP is locked up. I'd suggest a set of chassis-specific (NOT "universal") such as SLP or Edelbrock TES, for a 88 TPI 350; the correct cat from Catco or CarSound, and a 3" cat-back of your choice, from any of a long list of suppliers including Hooker, Dynomax, Slowmaster, Edelbrock, Borla, SLP, etc. etc. etc. All else is totally in vain, until you get EVERY PIECE of the LG4 stuff off of it, from the heads to the street.

I'd suggest a Comp XE268 cam, and a Performer RPM, or a ZZ4 intake off of ebay.

In no event do I see anything more than 350 HP in your combo, even after fixing the weak points in it; unless the heads have had a good port job done to them. That's assuming of course that they're one of the actual good castings. Post the numbers, and let's make sure of that. It's pointless to take as fact some kind of "325 HP 327" drivel. Just because they "came off of" such a thing, doesn't mean that they're what the factory put on it.