Roostmeyer

iTrader: (3)

I may be getting a good deal on some barely used pro lightening 200cc's with a k4 spring kit. What i need to know is what type of valve springs should i buy if I buy these heads. The k4 kit springs are:

Designed for Roller Cams, this kit includes 1.540 Dual Springs (220 lbs Seat pressure at 1.950/580 lbs open pressure, 720 Max Lift Manley Chrome Moly Retainers & Locks 10°). Assembled. 7/16 Rocker Arm Studs.

The k3 is:
Designed for Roller Cams, this kit includes 1.540 Dual Springs (190 lbs Seat pressure at 1.900/450lbs open pressure, 660 Max Lift Manley Chrome Moly Retainers & Locks 10°). Assembled. 7/16 Rocker Arm Studs.

and the k2 is
Designed for Mechanical Cams, this kit includes 1.460 Dual Springs (135 lbs Seat pressure at 1.800/320 open pressure, 600 Max Lift Manley Chrome Moly Retainers & Locks 7°). Assembled. 7/16 Rocker Arm Studs.


Now my cam-card is at home so i'm not sure what the recommended spring rates are for my cam. I think its the 268HR-same as the 270HR for retrofitted lifter cars. The specs are 218/224 @ . 05 and .495/.502 lift. I'll be using this cam with my stock shortblock with new rings, bearings, etc. with the pro lightening 200's and an lt1 intake. I will be using stock lifters. Other things are in my sig. DD2000 shows a peak at 5500 rpm. Just guesing i'll probably be shifting a little before 6000rpm.

What i need to know is what type of valve springs should i buy if I buy these heads? The comp cams 987 springs look good but will they stop valve float at 6000 rpm? Also would these springs being 1.440" diameter fit on 1.550" retainers? and finally whats the most i can safely shim the springs? I'd need to shim these springs down from 1.95" to 1.8" installed height.

Comp cams 987 springs:
1.440'' diameter double spring w/damper. Valve lift up to .600''. 130# @ 1.800'' closed, 325# @ 1.250'' open, coil bind @ 1.150''

I'm kind of in a bind because i can't seem to find any springs with more the a 135lb seat pressure and less than 200+ seat pressure. I'm also not sure how much pressure the stock lifters can take either. I'm wanting to go to a 383 in the next year too if i can afford it with a slightly bigger cam (274hr?) so i would like to keep my options open for later also. Finally if this deal falls through should i buy a k2 or a k3 spring kit?

Roostmeyer

iTrader: (3)

ttt

basicly to summarize can i run 1.44" springs in 1.55" retainers, and is the 987 springs stiff enough to preven valve float at 6000rpm?

Thanks

RB83L69

You really can't run 1.45" springs in 1.55" retainers. Nothing will fit tight like it's supposed to, so the spring will "walk" all over the place.

Spring pkg #2 would be adequate for your purposes. The other 2 are way overkill.

With a 218 degree cam, you're not going to be making power past 6000 RPM, probably not even up to that; no point in getting carried away with stuff that won't matter. 5500 peak actually sounds about right. If that's where it makes peak power, don't wind it past that before you shift, you'll slow the car down.

You want as much seat pressure as you can get, and around 300 lbs pressure at peak opening. The 987s or that package would give about those results. Either would work well with the cam in question, even with 1.6 rockers (which I'd strongly recommend).

There's no limit to how much you can shim springs, as long as they aren't over their limit at full open. i.e., look at the shortest length given in the spec, and shim them to that at full open with the cam & rockers you are using.