CAM and VALVETRAIN gods, in here!

guys, i am in dire need of help. i think i have a solution, but i want as much experience and advice as you all have before i spend more money.

i have a 95 LT1 stroker, fully BP'd and balenced, the works...
over 5-5500rpm's, i hear the lifters act up, and eventually the plunger/cap/clips blow off and end up in my oil pan:cry: :eek: i cannot have this happening, this motor cost waaaay too much. i don;t know why it's doing it, but i have a feeling that it's something between the valve springs and the stock lifters. i am 99% sure that i am setting the lash correctly (used multiple methods from shoebox's site) and i have polylocks

i called comp cams, gave them the details, and they reccomended this setup.

my cam is PN 07-000-8

with the 1.6 cc magnum rollers, this equates to .547lift/220 dur. on the intake and .533lift/224 duration on the exhaust, the lobe sep. is 112* +4*advanced, so if i remember , that's like a 108* centerline (i'm not sure, pretty cam stupid here;) )

i have stock lifters for now, and i was told by the builder my springs are 120 seat pressure / 250 open.

so i told comp cams this, and they said that's too little on the springs, they need to be at least 135 seat/ 340 open to be able to rev @ 6000rpm's.

they reccomend getting the 26918 springs and the pro mag 885 lifters.

please tell me if you think this will help, who has used these parts, and how are they working for you. i need this info quickly, i have a show the first week in august and i have to get heer running in no less than a week and a half. thank you very much for your help:cool:

160 seat and 350 open is enough

If ya got stock lifters they are fine v the comp lifters. Get the retainers and locks that go with the new springs.

A stock cam has more spring pressure.

Yeah - before I saw your pressure numbers I figured it was the valve floating off the nose of the cam and crashing back into the lifter - hense breaking them. That nose pressure is way too low...Stock pressure is 275 open. You should be between 125-150 seat and 295-340 open.

Use STOCK OEM lifters or the 850-16 lifters from comp with the 26918-16 beehive springs and your problems will be solved.

Bret

ok, a tad more info for you guys. i've replaced just about every lifter in my motor twice. the first set was the comp-r's, which i heard here sucked big time. i then switched back to stockers, and they blow CONSTANTLY. i don't even drive my truck that often, seriously no more than 2000 miles a YEAR, and this keeps happening. i just want it fixed once and for all. i'm willing to buy the pro mags if they will hold up better in the upper RPM range. comp says they will be a little stronger. what's the difference between the 885's and the 850's?

also, can someone please explain "valve float" in idiot terms? i really want to learn and can;t always get straight answers:)
machinistOne, what do you mean by nose pressure?

thanks so much for the help guys. i feel confident that i can fix this myself and the go on and fail emmissions :LOL:

ok, a tad more info for you guys. i've replaced just about every lifter in my motor twice. the first set was the comp-r's, which i heard here sucked big time. i then switched back to stockers, and they blow CONSTANTLY. i don't even drive my truck that often, seriously no more than 2000 miles a YEAR, and this keeps happening. i just want it fixed once and for all. i'm willing to buy the pro mags if they will hold up better in the upper RPM range. comp says they will be a little stronger. what's the difference between the 885's and the 850's?

also, can someone please explain "valve float" in idiot terms? i really want to learn and can;t always get straight answers:)
machinistOne, what do you mean by nose pressure?

thanks so much for the help guys. i feel confident that i can fix this myself and the go on and fail emmissions :LOL:


The lifters are NOT at fault. More than likely ya don't have enough spring.
Nose pressure is the spring pressure at max lift.

Float is when a valve does not follow the cam lobe profile due to lack of spring pressure.

The lifters are NOT at fault. More than likely ya don't have enough spring.
Nose pressure is the spring pressure at max lift.

Float is when a valve does not follow the cam lobe profile due to lack of spring pressure.


thanks a bunch! i really appreciate it!:cool:

Anytime,glad I was of some help.

can someone please explain "valve float" in idiot terms? i really want to learn and can;t always get straight answers

Valve float is when the spring can not keep the valve(or lifter) on the cam due to too much rpm. The cure is stronger vave springs. Valve float is not always bad ie: comps launcher seris cams. Valve float can be used as a shift point indicater or rev limiter,or to get a little more power out of the engine. The big downsides of it are that power can dramaticly fall off as valve timing gets inappropriate AND WHEN THE PISTON kisses THE VALVE or CRASHES RIGHT INTO IT- severe damage may occur.

Valve float can be used as a shift point indicater or rev limiter

I wouldn't use it for either. and the launcher series cams are designed to withstand the force from the lifter slaming back on the cam. Other cams are not and valve float will cause damage to them. I would avoid valve float all together.

In simple terms, you don’t have enough pressure to keep the cam lobe, lifter, pushrod, rocker and valve in firm contact with each other when you get to the high point on the cam lobe and when that happens the plunger in the lifter slams in to the retaining clip trying to take up the slack and pops it out/ends up in your pan…