[staygreek]

first off im building more of a pro touring driver than a strip car...
specs
496ci
10.25:1
PRO-COMP ALUMINUM CNC PORTED RECTANGLE PORT MANLEY VALVES (2.25 X 1.88) i think good up to 650 lift
1.7 RATIO FULL ROLLER ROCKER
bg mighty demon 750.... think i need 850
air gap intake
cam
@50 238 248 cut on 109 lift 540 540
rest of car
th350 3000 stall
3.91 gear
motor is new not in car yet would like to make changes while its on the stand

[cstraub]

What is your max rpm you wish to turn the engine?
Is the cam a flat or roller lifter lobe?

[staygreek]

6500 maybe 7 at most
flat

[kettbo]

Bobby,

238/248* and .540" lift is more appropriate to a moderate street 454 and 6000 rpm than a 496 with rectangle port heads you wish to rev to 6500 or 7000 rpm.
Just when your heads get going, the cam will lay down. Simply not big enough to feed the beast or get the job done. The 496 will make that into an RV cam.

[71454Chevelle]

Originally Posted by staygreek

6500 maybe 7 at most
flat

That cam wont come close to doing that.

[71454Chevelle]

Originally Posted by kettbo

Just when your heads get going, the cam will lay down. Simply not big enough to feed the beast or get the job done. The 496 will make that into an RV cam.

[cstraub]

Wont even get close to that kind of rpm, what you have will be done by 5200 to 5500 rpm in 496 cid. If this is a pro touring car I would recommend hyd roller. You can get more power out of a "smaller camshaft" and still maintain some type of street manners. The investment is more but the results will more then please you.

I would shoot for a max HP rpm of say 6200. She will still pull beyond this but the HP will fall off after this point. This kind of max HP rpm still give you street manners for the pro touring aspect of the engine but still make a legit 600HP.

If budget constraints warrant a flat tappet then thats what you will need to run but that cam will not come close to getting you to 6500 rpm.

If I can be of help pm me or call and I can design you something to get you where you want to be within reason.

[staygreek]

soooooooooo somthing like this?

lUN-30210
Cam Style Hydraulic flat tappet
Basic Operating RPM Range 3,500-7,000
Intake Duration at 050 inch Lift 245
Exhaust Duration at 050 inch Lift 255
Duration at 050 inch Lift 245 int./255 exh.
Advertised Intake Duration 295
Advertised Exhaust Duration 305
Advertised Duration 295 int./305 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.605 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.612 in.
Valve Lift with Factory Rocker Arm Ratio 0.605 int./0.612 exh. lift
Lobe Separation (degrees) 110

[staygreek]

or is this still too small

[kettbo]

while I won't say your choice in the post above is ideal, you have caught on to the theme I was working toward...big engines require big cams!

[Jason Snyder]

Originally Posted by staygreek

soooooooooo somthing like this?

lUN-30210
Cam Style Hydraulic flat tappet
Basic Operating RPM Range 3,500-7,000
Intake Duration at 050 inch Lift 245
Exhaust Duration at 050 inch Lift 255
Duration at 050 inch Lift 245 int./255 exh.
Advertised Intake Duration 295
Advertised Exhaust Duration 305
Advertised Duration 295 int./305 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.605 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.612 in.
Valve Lift with Factory Rocker Arm Ratio 0.605 int./0.612 exh. lift
Lobe Separation (degrees) 110

that cams rpm range looks like it is rated for a 396 , not a 496 , add 20 degrees more duration for the 496 .

[cstraub]

Jason and Ketbo are correct, you have added cubes over the common BBC of the past. You also have piston speed. That extra stroke increases the piston speed in the engine. Piston speed will "swallow" head volume and cam duration as compared to the same engine with equal cubes but less stroke.

Also with those heads you have I believe they need a little tighter duration split

[the heckler]

fwiw...I run this flat tappet solid lifter cam in my "street" 496. 10.5:1 with edelbrock oval ports and 850 dp. makes 600 hp on pump gas....
The cam is a comp cam part # 11-679-5.....xs290s....
Duration at .050 252/260
lift .598/.598
lobe sep. 110
lash .016/.016
works great but requires a vac reservor for the brakes...

[Chris Stanwyck]

Originally Posted by the heckler

fwiw...I run this flat tappet solid lifter cam in my "street" 496. 10.5:1 with edelbrock oval ports and 850 dp. makes 600 hp on pump gas....
The cam is a comp cam part # 11-679-5.....xs290s....
Duration at .050 252/260
lift .598/.598
lobe sep. 110
lash .016/.016
works great but requires a vac reservor for the brakes...

like that choice...very streetable in a 496...like it even more so cut it on a 112 or a 114 & won't hit so hard on your turbo 350....plus a bit more vacuum that should not require the resevoir.
600lift, duration in the late 250's @ .50, with solid lifters in a 496...nice street piece with a ton of power.
The cam you have will hit too hard early and die off fast fo sho....and you will leave too much horsepower on the table.
You can always contact one of the cam guru vendors on this site as well...worth the few extra bucks IMO.

stayingmacedonian

[wildman926]

I would go with this one for a solid ft. It has PROVEN performance -
Lunati 402A7 -
Solid, rough idle. Good cam for bracket racing in 396-454 cubic inch motors. Needs 3500 RPM stall converter, headers, 10.5:1 compression ratio and 4.10 gearing.

Advertised Duration (Int/Exh): 288/296
Duration @ .050 (Int/Exh): 255/263
Gross Valve Lift (Int/Exh): .612/.630
LSA/ICL: 110/104
Valve Lash (Int/Exh): .024/.026
RPM Range: 3000-7000

Here is a video of a 496 with one in it. I run the solid roller version of it in my Chevelle. This is NOT my car -

Short+video+of+my+El+Camino+idling.