Guru_4_hire

what does one need to consider in changing the springs?

Spring pressures? etc.

OK the springs I have are rated at
115# at 1.7
300# at 1.25

The springs Compcams recommends are rated at
120# at 1.75
280# at 1.25

then manley has some springs rated at
110# at 1.7
285# at 1.21

Is there any compelling reason I cant run the roller cam with the springs I have now?


[Modified by Guru_4_hire, 7:26 PM 8/29/2003]

Guru_4_hire

I really could use a hand with this

MotorHead

Other things to consider is where the spring is going to bind, roller cams usually have much higher lifts and the springs you have on there might not be compatable. I am going to switch to a roller cam too and that is an expensive setup so I will put in the recommended springs. :D

zwede

What kind of roller? Hydraulic or solid? If it's a solid with high lift I'd look for more spring pressure. The solid rollers have very fast ramps and low pressure will make the valves float before the cam is done.

Your springs are pretty good for a hydraulic roller. You need 050 safety margin to coil bind (max lift for springs has to be atleast 050 more than max lift of cam).

Guru_4_hire

I have .038 safety margin from coil bind

It binds at 1.16

and the cam I want to use is a x-treme energy 270 hydraulic roller cam.
it has .495/.502 lift

Fevre

From the specs you posted I would say you are fine to run those springs with a hyd roller cam. You'll like the wider power curve the hyd roller cam offers. :thumbs:

Guru_4_hire

With my aftermarket heads -- and an edelbrock intake I should be over 400 easy

zwede

That's pretty tight. Don't know if I'd run a spring so close to bind, personally.

GDaina

spring pressure when the valve is open is the critical factor. If the spring pressure is too high for the cam, that is recommended pressure from the cam mfg., you will break the cam, not right away, but somewhere down the road. I don't know if 20 pounds over will matter. I would call the cam mfg. tech line and ask.

Guru_4_hire

I dont wanna call compcams cause they would tell me to buy their $100 springs.

mrvette

Guru, the head shop has to determine the installed height/bind/pressures on those springs, and the bind is determined by the height of the coil seat depth of machine cut...which also affects the valve closed/spring extended pressure too, of course...ten mills is a bit too tight on that clearance, you MAY break a spring, but then again you may not....thing is at various rpm's the springs reach various harmonics....vibrations along the length/coils of the springs and if those excursions are going hard enough against the action of the cam, you may snap spring metal....that's why the clearances have to be larger....
than an absolute bind....

GENE