Cam upgrade dilemma!

[wicked70496dart]

Hey Guys, I have a cam upgrade question! My engine is apart to inspect and is being freshened up. Sent the heads to Fastlane Machine to flow them, check max retainer to seal clearance and a valve job with blending the bowls. The heads flow 303.0 @ .700 intake and 228.9 @ .700 exhaust. Retainer to seal clearance is .705. Heads are stage VI. My cam now is Hughes solid mechanical .620 lift @ 272 duration. Engine is 383/496 12.2 to 1 with Hughes valve train and girdle. So I thought about upgrading the cam to Comp Cam .650 lift with 290 duration @ .050. I have .185 piston to valve clearance on exhaust and .145 on intake now with the .620 cam.

What's everybody's thought on this cam change? Do you think this cam is too big? Think this cam may slow the car down? Converter is a 5500 stall with 4.56 gear in the car now and ran 9.76 @ 135. What do you guys think? Thanks, Matt.

 

[bOb shingler]

waste of money.

 

[roccodart440]

My reaction to the post is you need bigger heads, not a bigger cam.

 

[moper]

What do the heads flow at between .000 and .550? If you're only opening the valves to .590 flow at .700 doesn't matter in the least.

 

[IQ52]

The previous posters are correct. Those STG VI heads are pretty soft. The last two sets of Stage VI heads we sent out, using a 2" exhaust tube, flowed like this.

Lift.............IN/EX........IN/EX

.100...........76/60........77/70
.200.........156/136.....160/135
.300.........222/188.....224/184
.400.........275/225.....273/220
.500.........310/256.....311/254
.600.........338/280.....335/271
.700.........344/297.....346/288

 

[rumblefish360]

My opinion on cam and heads in a spirted driver or racer is use as much lift as you can get up and until the head flow quits. Select the cams duration based on the rpm range it operates in. Lift on the heads flowing ability. Use the heads potential to its maximum when ever possible.