I was thinking of running some Pro Lightning with 2.08" +.100 valves,200cc heads with 64 cc chambers on my 357. I was wondering if the dual springs with lift up to .650" lift and .100" taller valves would have too much spring pressure for a comp XE268? Can one of the springs be removed for cam break-in? Should i have any problems? and is this a good idea?

 

No. They should work fine.

Yes. You can remove the inner spring (not the damper, the spring) to lower the pressure; this is almost universally done in building professional racing motors.

No.

Yes.

It's almost impossible to have "too much spring", except when the seta pressure exceeds 180 pounds or so. Seats will not stand up to that degree of pounding for very long with unleaded gasoline. As long as they're set up for around 110-120 lbs of seat pressure and around 300lbs open, they should be fine.

The taller valves are used to allow more lift: that gives that much more clearance between the retainer and the valve guide.

 

Well, I'm going to disagree here slightly. If you are running a hydraulic cam you're going to run into problems of collapsing the lifters when you get much over about 135lbs seat pressure and 300 open pressure. With an old high mileage flat tappet hydraulic you'll almost surely risk wiping a lobe if you get up to those kind of pressures, to boot. With a new cam that's less likely.

Remember that stock springs are only about 65lbs seat pressure and about 220-230 open. Pro Lightning heads are available with springs that are compatible with flat tappet hydraulics and I'd suggest you use them and not go for the gorilla springs. You'll want something with about 110lbs seat pressure and about 280 open to work with the XE cam- dual springs not necessary to reach this level.

Yes, you can remove the inner spring during break-in.

 

WAY TOO MUCH head for the xe268 cam. The 268 is a good street cam, but that's about it. A good set of l98 heads cleaned up will be more than the 268 needs. I'd bet you'd see no differance on a dyno, maybe less tourqe. That 268 is only going to produce so much power, no matter what else you do. BIGGER isn't always better. A 1.94 valve head will work well till at least 6000 rpm.

 

Can i remove the inner spring and just run the outer spring all the time by itself? The reason i am getting these heads with daul springs is that they come like this and are a great deal.

 

Is it possible to only run the outer spring?

 

Yes, it's possible; but I'd check their pressures and see what they are, if they're in the range that both Damon and I described at the lift you're going to use, I'd use them as they are.