Here is what i sent them... Could you please recommend a good cam for me.... I am looking ot get the most performance possible... and I do like the rough idle... I have a 1988 Iroc Z28 Engine Size: 350 Bore: 4" Stroke: 3.48" Compression Ratio: 9.3:1 Connecting Rods: Stock Rocker Arm Ratio: Stock(1.5 I think) Intake: Stock TPI Computer Controlled: YES Meet Emissions Standards: NO Cylinder Heads: Stock, but will be ported eventually Valve Size: Stock intake, Stock exhaust Pistons: Stock Transmission: B&M 700r4 Street Auto Converter: B&M 2100 Hole shot converter Rear End Ratio: Currently 2.77, but will be 3.45 eventually Rear Tire Size: 245/50/16 Fuel Used: 91 octane pump gas, sometimes 93 octane Exhaust: Single 3" Flowmaster 40 series, no cat. Headers: Flowteck ceramic coated 1.5" primary's and 2.5" collecters Curb Weight: 3400 lbs RPM Range: 1000-5500 Car Use: daily driver, fun at the track, street racing Computer has: JET stage II performance chip Current Cam: Stock GM 10066049 int.415 exh.430 int207 exh213 lobesep 117 this is what they recommended.... PART NUMBER 08-502-8 ENGINE CHEVY SM BLK 305-350 GRIND # CS XR269HR-12 DESCRIPTION HYD ROLLER CAM INT EXH VALVE ADJUSTMENT HYD HYD0 GROSS VALVE LIFT .495 .503 DURATION AT .006 TAPPET LIFT 269 276 VALVE TIMING OPEN CLOSE AT .006 INT 26 62 EXH 74 22 THESE SPECS ARE FOR CAM INSTALLED AT 108 INT C/L INT EXH DUR AT .050 218 224 LOBE LIFT .3300 .3350 LOBE SEPARATION 112.0 INT MASTER ID 331 ADVANCE 4 EXH MASTER ID 331 RECOMMENDED CC VALVE SPRINGS 986-16 my question is..... Is this a good recommendation.... or should i go with something else... I know there are a million opinions on the right cam... also this car is gonna be mainly street driven, but taking to the track some... please give me some help, is hte lift enough/too much... is the duration tooshort/toolong??? thanks guys

its a good recommendation, but you can do better. that cam will not "idle rough" in a mild motor, but will be nice on the street, and in a near stock motor it will probably idle a bit rough. its also TPI computer compatible, by the looks of it.

The reason I say you can do better, is because the .050-.050 VS advertised is almost the same as a Flat tappet XE262 cam. 218/224 but LESS advertised on the XE262.

that means your extra "advertised" duration is going to waste on a perfectly good roller cam. of course, they probably recommended it because they figured you didnt want to upgrade your valve spings.

but if you want to get the best value, upgrade springs / rockers / pushrods and get a cam with about the same .050-.050 but alot less advertised and a little more lift.

thats MY recommendation, and other people may have DIFFERENT recommendations.

Thats nice.... Do all the mods you said you'd do "eventually".


Then change the cam.

King,

It appears that they DID recommend new springs with the cam (as they commonly do).

All of their XR roller series have specs that compare to the XE flat series like that. I can tell you, having changed the otherwise identical motor from a XE274H (230°/236°) to a XR282 which has the same .050" spec, the difference in the "advertised" duration is negligible, and the roller cam runs a whole lot stronger than the flat did.

Their recommendation is actually pretty aggressive for them; they usually tend a little toward the conservative. It looks like a good choice to me for your engine after the mods you talk about, but will probably slow the car down and merely make it drink more gas if you put that much cam in it as it now sits.

Believe the valve spring recommendation. Note that they are the 986 spring, which is a 1.45" outer diameter dual spring with damper as opposed to the stock 1.25" diameter single spring with damper; this will require machine work to the heads. You can't put any more lift in without having to do this, if you want long-term reliability. You really should upgrade the rocker arms at the same time too, get rid of the lame rubbery stock ones and put something in with a consistent ratio.

the only other mods i am planning on doing is port and polish the heads, change the rear end from 2.77 to 3.4x and upgrade the ignition.... so i should do all that before i get a cam?

then do the heads when you go inside for the cam.
Get a good set of aftermarket non-stamped rockers.