phirepower

iTrader: (2)

I have a Gm 846 cam in my car, full bolt ons, midtubes, ported polished airfoiled tb, no head work. I am currently running lt4 valve springs and stock rockers (due to budget constraints) here are my cams figures

12370846 Hydraulic Roller Design
This hydraulic roller design contains eccentric for mechanical fuel pump. It is for off-road use only. The duration at .050" tappet lift (intake/exhaust) is 222/230; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 509/528. Valve lash is zero/zero and lobe centerline is 112 degrees.

I realize that this has less intake lift than a 1.6 rr hotcam, and slightly more exhaust lift, but with longer duration. I am wondering what hp numbers you guys figure I am making. And how much I'd gain upgrading my springs and going 1.6 rrs.

Any Ideas?

ElkySS

iTrader: (6)

id guess 330-340 ish through a 6 speed if you dont get valve float from the lack of a good spring

96capricemgr

iTrader: (1)

Wrong springs. Getting the same lift with 1.5 rockers as with 1.6s means more movement of the HEAVY lifter and harder to control.

Keep the rpms down you wont be able to really use this cam and float can damage a lot of stuff.

phirepower

iTrader: (2)

Good thing I've only clocked 30 miles on the motor since I built it. Is that a fact that it has the same lift regardless of rocker size? That doesn't make sense to me, either way I have since bought new springs I am just lazy and haven't installed them yet. Beehive crane's

Assuming I don't have serious valve lift, would my car still beat a hotcam 1.6rr car with the same supporting mods?
I can drive and have a nasty transimission, (viper build spec T-56, ram HD clutch)

phirepower

iTrader: (2)

anyone else

My95Z

iTrader: (8)

Going from 1.5 to 1.6 will increase your lift to .543" intake and .563" exhaust thus increasing CFM if the heads support more airflow at the greater lift.

This cam has more duration, same LSA, and more lift (both with 1.6 RR's) than the hotcam so you can expect slightly better #'s.

ss.slp.ls1

iTrader: (36)

Good, I honestly wouldn't drive it at all until you get the new springs on. You will have catastrophic failure once one of those springs goes.

With 1.6 rockers the lift will be .543"/.563".
You will have more higher lift and slightly more duration than the LT4 hotcam w/ 1.6 rr's. That should give you more mid-range and top end than a LT4 hot cam w/ similar supporting mods.

StealthFormula

iTrader: (35)

Yes I would sell your LT4's and purchase a better valve spring such as the Crane 10308-1 kit. The LT4 valve springs are barely sufficient for the LT4 "hot cam" and people even then have had issues. The Cranes are a nice spring and will allow you to run 1.6 RR's with your cam.

phirepower

iTrader: (2)

so you guys think that even given my 846 on 1.5's is only making .509 .528 lift that the springs will fail? I thought I'd get a season 0ut of em before I would be forced to replace them

StealthFormula

iTrader: (35)

The biggest issue with the LT4 valve springs is that they are quite weak. An LT1 with a stock cam works great with those springs but sometimes people even have issues with them while running the Hot Cam.

phirepower

iTrader: (2)

Guess I'll look for good prices on some new springs. Has anyone actually run the lt4 valve springs and broken one?

ss.slp.ls1

iTrader: (36)

I think valve float is much more common than breaking springs. But that too can be very harmful to your valvetrain.