[86SSman]

I am building a new engine for my car. This will be a weekend driver/strip car. I have a few choices of combos, I am wondering which one would be the cheapest and still yield decent power. These will be on a chevy 350 4 bolt main with a 270H magnum comp cam (270dur .470/.470 lift) performer rpm intake, accel ignition, and uncapped headers to accomodate the even duration cam.
Combo #1: '75 350 stock pistons with (58cc)5.0 HO heads from an 84 camaro.
Combo #2 Same engine with 1996 (65cc) swirl port heads.
Combo #3 11.93:1 pistons and 882 heads

I already have the HO heads and the swirl port heads. Any set that I use will be port matched to the intake and headers and polished.

[johnnymopar]

personally, i wouldn't use combo#3 because of the higher compression. I don't know, but if you use high-octane pump gas what is the limit for compression? I think you're getting into the area of racing fuel.

Anyway, combo 1 sounds good because of the smaller cc heads it will raise compression, but what size valves are you using?

I think i would go with the heads with largest valves.

JB

[Jooooooe]

Truthfully, if your using a cam with more than .450 lift and not using 2.02 heads, your cheating the motor of it's true potential. Yea, I know you will broaden the motors range with a larger cam (depending on the choice of cam) and get more hp, but you know how it's takes time for your computer to load info and the more complex the info or graphics the more time it takes. It's refered to as bottle-necking because you have more info coming than your capable of receiving all at once. Kinda the same thing with oversize cams and not enough valve size or port preparation. I know it's actually more technical than that and there are other factors to consider, but I'm trying to keep this simple.

[Jooooooe]

Just want to ad to my last post, I notice you've mentioned low cost, I purchased a pair of 2.02 heads from California Discount Warehouse, they are refurbished and have new Manley SS pro-flows, Springs, etc., no core required 450.00 plus shipping. They always have ads in Super Chevy.

[dmorris1200]

Johnnymopar & Jooooooe great points, breathing is key. It's the difference between you or I breathing normally or being forced to breathe through one of thoes little coffee stirrer straws(who wants to do that). Had a 351 Windsor in a Cougar that needed valve seals(smoked on start-up). My friend talked me into dropping the heads and intake off at his machine shop. Without going into all the specifics of what he did(he did alot), I put that motor back together and swear I could feal the difference.

[86SSman]

the 1996 heads have the "swirl" intake runners. They also have 2.00 intake valves. They came off of a vortec 350 chevy truck engine. I know that they will flow great, especially when I port and polish them. Opening the heads up is a must when running a larger cam, and, when done properly, it can make a set of heads flow a whole lot more than one would think.

[1meancuda]

I think the swirl heads sound like a good idea. If you are taking the heads into a shop to get the port/polish job done, you could always have them install bigger valves. Just a thought.