I,m building a 350 to put in my 86 z28, here is what i have so far. I have a 75 350 4 bolt main bored 40 over, Gm oreformance vortec heads 1.94 intake 1.60 exaust, new cast crank, Gm vortec intake. I already have two cams in mind a melling 350 hp 327 replica or a comp 270h 249-CL12-211-2 or any other cam sugestions are welcome. I just want the best cam for my car. I'm don't wan't to run a stall convertor.

 

DON'T run the 151 replica. That's just about the worst possible cam you could run.

Vortec heads have great intake port flow, but the typical crappy exhaust port flow of all stock heads. They benefit DRAMATICALLY from an asymmetrical cam, with larger exhaust lobes. That rules out the 270H as well: works good with aftermarket heads, with better exhaust ports; can be improved on for stock heads.

I'd suggest a Comp XE262, or a cam from one of the other major mfrs with similar specs; 215°-220° of .050" duration on the intake, and about 10° more than that on the exhaust, and peak lifts in the .460" -.470" range. Obviously you want good vigorous valve action (totally unlike the 151 cam, which is about as lazy as they come), so that the valves stay as far open as possible, for as much of their open time as possible; rather than hanging around the seat and not doing anything. That's about as much cam as you would want in front of a stock converter. Any more, it will have a real soggy bottom end, with no leave.

Use flat-top pistons. With stock deck clearance and the typ[ical .020" offset in replacement pistons, you'll end uyp with around 9½:1 CR, or maybe just a bit more; less than 10:1. It will run comfortably on pump gas.

 

Are these vortec heads completely stock? If so I wouldnt reccomend a cam with anything over .470 lift on the stock springs they cant take it. I wouldnt reccomend that crappy 327 cam, its a good stock replacement but there are many other better cams that would suite a mild 350 a little better. I dont know anything about the 270H so I cant give you any input there. I think either the comp cams XE256 or XE262 cam will be perfect. The XE256 will give an awesome amount of low end torque and is very good for daily driving while the XE262 gives up just a little bit of that torque for some hp and is also gould for daily driving and you can make up for the loss of torque with gearing so I would probably say go with the XE262. Also you dont list a compression ratio. Your ideal compression ratio should be anywhere from 9:1 to 9:5:1. Good Luck.

 

thanks for the help

 

comp cam as rb said..you will need a cam that favors exhaust.

let us know what u go with.

 

i think i'm going to use a Comp XE262