Advance or retard

[88bluestar]

441 chevy head, mild porting, 1.94/1.50 valves , 355cid with about 9.4:1 compression, roughly 6.50 gear ratio on a tight 1/4 mile dirt track, with american racer kk704 tire. 750 cfm holley dp carb, 2701 intake.Forged piston on stock 5.7 rod, stock crank. 1 5/8" headed. 3000 lbs car

I have two cams, which one would you use, and how would you time it as far as advance or retard for the best power.

Grind No./Type: 300-HL HYDRAULIC
Application: High perf. Street/strip. Lopey idle. 2800 stall. 4.11-4.88 axle ratio.
Up to 750 CFMCarb. 10.5:1 compr.

RPM-Range: 3000-6500
Value Lift Int/Ext: .485/.485
Value Lash Hot Int/Ext: .000/.000
ADV Duration Int/Ext: 300/300
.050 Duration Int/Ext: 234/234
Lobe Center: 108Grind No./Type: 300-HL HYDRAULIC Application: High perf. Street/strip. Lopey idle. 2800 stall. 4.11-4.88 axle ratio. Up to 750 CFMCarb. 10.5:1 compr. RPM-Range: 3000-6500 Value Lift Int/Ext: .485/.485 Value Lash Hot Int/Ext: .000/.000 ADV Duration Int/Ext: 300/300 .050 Duration Int/Ext: 234/234 Lobe Center: 108

or

Cam Style: Mechanical flat tappet
Basic Operating RPM Range: 2,500-7,000
Intake Duration at 050 inch Lift: 256
Exhaust Duration at 050 inch Lift: 264
Duration at 050 inch Lift: 256 int./264 exh.
Advertised Intake Duration: 287
Advertised Exhaust Duration: 297
Advertised Duration: 287 int./297 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.504 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.504 in.
Valve Lift with Factory Rocker Arm Ratio: 0.504 int./0.504 exh.
Lobe Separation (degrees): 105
Camshaft Gear Attachment: 3-bolt
Intake Valve Lash: 0.026 in.
Exhaust Valve Lash: 0.026 in.

[statsystems]

The solid.

[F-BIRD'88]

The solid... Install at 99 deg in c/l..

If too snappy off the corners (traction) tighten the lash up.

[MadBill]

And if traction's still an issue, retard the C/L to 101-102°

(Isn't this starting to look like those Burma Shave sequential signs? For anyone under 60, see here: https://en.wikipedia.org/wiki/Burma-Shave)

[Keith Morganstein]

Heavy car, tight 1/4 mile. With those eng specs, cam # 1, installed at 104.

[stn2racing]

I might add that it dry slicks often, not very much traction

[David Redszus]

Are we drag racing or running in circles?

If traction is an issue, it should be addressed before messing with the engine. Fix the traction problem.

It is very common to see high power engines running on short track dirt and never be able to use more than 60% throttle and yet drivers clamor for more horsepower.

Spend your money on a very good data system, not engine parts.

[Carnut1]

Cylinder pressure makes a difference. Flow numbers from the heads would make this an easier choice but since "mildly ported" was written I can estimate flow. I feel with set compression and not great flowing heads the solid will drop cylinder pressure lower than the hydraulic. I think the hydraulic will be better downstairs and run up to 6500 rpm maybe a bit more with careful spring selection. The solid will pull better up top where the heads will be sucking wind. The extra low end torque may be hard to use on the track given the conditions. I have a feeling the driver will make either cam a winner. I feel the smaller hydraulic will give the better more usable torque curve. I am not a cam expert. Thanks, Charlie

[stn2racing]

Planning to run k-750 valvesprings with either cam. I was thinking if I run the small cam, advancing only to 106, give it the chance to make a bit more up top while softening the torque a bit, using gearing if need so to make up for anything out of the turn. Also using a 1.6 rocker on the intake only on the small one. I've used the solid before in a similar type of engine but valves were 2.02/1.60, advanced 4 degrees, and using a stock 2 bbl intake/4412 Holley carb on a adapter(torque was off a bit, but a very competitive cam none the less.

[stn2racing]

If I were to throw a set of 906 or 062 vortecs on, with 1.94/1.50 valves, 5 angle job, very light porting... what do you think, does that change anything?

[BigBro74]

Planning to run k-750 valvesprings with either cam. I was thinking if I run the small cam, advancing only to 106, give it the chance to make a bit more up top while softening the torque a bit, using gearing if need so to make up for anything out of the turn. Also using a 1.6 rocker on the intake only on the small one. I've used the solid before in a similar type of engine but valves were 2.02/1.60, advanced 4 degrees, and using a stock 2 bbl intake/4412 Holley carb on a adapter(torque was off a bit, but a very competitive cam none the less.

ME (and this is just me)- I would use that solid - installed at about 100. that 105 lobe center, with those small heads and low compression will be nice, and you have pretty decent gear- it will work well- I would use 1.5 ratio rockers to start with- if you find you need more top end you can put them on later. Please spend for the ISKY single springs if you have to buy them (check- 235-d?? p/n I believe) they hold up pretty well......

Jason

BTW- one of the guys I help runs that cam in a UMP SS car -(3200lb/4412 2bbl) won two features and point champ last year local.....

[Keith Morganstein]

Planning to run k-750 valvesprings with either cam. I was thinking if I run the small cam, advancing only to 106, give it the chance to make a bit more up top while softening the torque a bit, using gearing if need so to make up for anything out of the turn. Also using a 1.6 rocker on the intake only on the small one. I've used the solid before in a similar type of engine but valves were 2.02/1.60, advanced 4 degrees, and using a stock 2 bbl intake/4412 Holley carb on a adapter(torque was off a bit, but a very competitive cam none the less.

Are you posting under two different user names?

[stn2racing]

I had started a new account recently because I couldn't remember the password. Some how my phone had the password for the other account, my bad sheesh. Sorry guys for the confusion.

[Keith Morganstein]

I wouldn't choose either cam you listed if I was building it. Now everyone has different ideas and ways. My experience on short track is asphalt, but most of those tracks were rough and traction limited. On 1/4 mile tracks the driver is on and off the throttle like a light switch. I don't think long duration cams for top end power is what gets it done. Cams in the 230 @ .050" range have worked very well for me. If rules allow for a solid tappet cam, I would select a solid cam in that range if over a Hyd.

To be honest, I've worked with Mike Jones for cams on many successful racing engines. Yes, quite a few wins and championships. Relying on Mikes vast experience in making cams for racing has really paid off for me.

[ZIGGY]

Gonna throw my 2 cents in here. Using the stuff and info you mentioned, especially dry slick tight quarter, I'd use the vortecs, the solid cam, put some more gear in it (hell yes) and put the car and/or driver on a diet. And I'm with BigBro, advance the cam and don't use the K750 springs.