Profiler 12* heads. What is a good VS seat pressure. My Cam Lift under .900. I run the PSI 1254 RML MAXlife spring set at 2.200 installed hight with 420 on the seat. Can I go to a weaker spring and would it make any ET difference???
Thanks in advance

That sounds like a lot on the seat.
Do you have your open pressure?

Regardless, the optimum spring will have adequate seat and over the nose pressure without being excessive.
This is really determined by many factors...
Valve side of the rocker weights. (valve, retainer, etc.)
RPM range.
The cam profile, more aggressive ramps will require more pressure, and more frequent replacement / maintenance.

I'd call Bullet, and discuss.

I would expect minimal ET change, unless your current setup is way off base.

Your numbers seem off. That spring is advertised as 350# @ 2.100 so how can it be higher at 2.200.

If you have .875 lift that spring should be set up at 2.065" closed.

Agree would check your checker. If found to be accurate I would say too high. Too much pressure means power to rotate cam against it. Also can not help lifter or rocker life span.

Think about the ceramic bearings deal. Have had 3 folks swear to .02 for bearing change in front wheels. So how much power to roll little tire compared to force a 400 plus Psi spring to open to what close to 1000 at W.O.? then how many are you openiong at onve time?

I ran about 350-375 closed, 1150-1175 open on my old 12* profilers, but that's what was spec'd to me by the cam manufacturer. I used PSI 1249's. Used PAC at first and had tons of issues, changed only the springs and issues went away.....

quote:

Originally posted by wideopen231:
Agree would check your checker. If found to be accurate I would say too high. Too much pressure means power to rotate cam against it. Also can not help lifter or rocker life span.

Think about the ceramic bearings deal. Have had 3 folks swear to .02 for bearing change in front wheels. So how much power to roll little tire compared to force a 400 plus Psi spring to open to what close to 1000 at W.O.? then how many are you openiong at onve time?

That extra spring pressure is also helping as it's closing the other valves too don't forget.

I don't have any scientific data for you but increased spring pressure doesn't kill as much hp as one would think. Too much is better than not enough in the broken parts department too. You lose control of the valve train you will break way more parts than high spring pressures ever will.

I went from mid 600s open to 820 and seen zero difference in ET. Not a hundredth. Valvetrain life greatly improved too.

quote:

Originally posted by 00 DEAD ON:
Profiler 12* heads. What is a good VS seat pressure. My Cam Lift under .900. I run the PSI 1254 RML MAXlife spring set at 2.200 installed hight with 420 on the seat. Can I go to a weaker spring and would it make any ET difference???
Thanks in advance

Cam lift has very little if any to do with the required spring pressure. From what you are saying I'd move to the PSI 1249 which is 375 at 2.200. That spring is good to 1" lift and will cover a good number of typical high end bracket cams along with TS//TD cams. Any more than required just wears stuff out faster.