I would like to know if somebody is shimming their stock hyd. roller lifters because of high spring pressure in order to insure they do not collapse?
Before I do this, I would like to know the pro and con’s of doing this.

I will be using about 145# seat and 400# open pressure.

Arnold

 

If you shim a hydraulic lifter to keep it from collapsing under load, are you not making it into a solid lifter?

Perhaps you meant modifying the travel of the lifter so that it acts like a solid after it collapses about the amount of a solid cam lash.
Isn't that a trick used when rules require hydraulic lifters, but you need to run solids?

Why so much spring over the nose?

 

Shimming hydraulic lifters is a common practice in NHRA Stock Eliminator. The tech department eventually decreed that the plunger must have at least .015 travel in order to be classified as a "hydraulic." The spring pressure you describe is not out of the ordinary for Stockers.

 

That camshaft and those lifters are not designed with that type of spring pressure in mind. Excessive spring pressure on a solid roller application often leads to premature cam lobe wear, I would imagine the same is true with a hydraulic roller camshaft.

 

These guys sells them...
http://members.aol.com/jallensherman...ingProduc.html

 

Well that depends on the camshaft and the rest of the setup. Too much pressure on a flat tappet setup not properly broken in will wipe out cam lobes. Roller setups are less likey to hurt the cam and more likely to hurt the lifter roller and bearings.

A billet camshaft will take about whatever you want to throw at it, just make sure the lifters are up to the task. Well correct that make sure the lifters and springs are matched for the intended usage.

Now unless you are rules limited why would you go thru the work to shim a set of stock lifters up? Comp R's (875's) will take that kind of pressure all day long, and more. Just seems silly to comprimise the parts in the system to pull something like that off.

Your spring pressures are not out of line, just realize that the 400lbs over the nose is going to be multiplied by the rocker ratio. So that 400lbs is actually going to be 640lbs on the rocker arm the rocker stud and the pushrod. So that means more deflection than either a lighter spring pressure or a smaller rocker ratio.

Bret

 

Bret,

I am using a billet cam but what kind of spring pressure would you suggest I use with my cam, knowing that I will shift at 6200-6300 rpm? Comp Cam Magnum Lobes 230/236@603"/.608 with 1.6 RR 114°. and Sealed Power hyd. roller lifters.

Arnold

 

Sounds like what you are using will be fine since your max RPM is realitively low and those lobes are not rediculously aggressive.

Bret

 

Too much spring pressure on even a properly broken in flat tappet camshaft will still wipe the lobes out prematurely. My friend's XE284 went flat after a year and a half with a good amount of spring pressure for a hydraulic flat tappet.

 

Bret,
again, which spring would you advise for my setup?
I've been looking at the:
Comp Cam 925: 142#@1.850" // 382#@1.242" coil bind 1.100" spring rate 395#

Comp Cam 985 140@1.830"/340@1.222" bind at 1.150" spring rate 333#

AFR stock 8016:140#@1.930" and 390#@1.320" // coil bind 1.140" // spring rate 410#

My favorite is the CC 925 but the AFR 8016 wouldn't cost a cent more because I ordered the 210cc heads anyway.

Thanks for your help
Arnold