OK, here's my dilemma.

I'm running out of money since BOTH of my thirdgen's have engine problems. They don't HAVE ANY. My iroc is a project car and my T/A is my driver.

I cracked both heads and blew both head gaskets. Small radiators in traffic at noon in the summertime with a mechanical fan really, REALLY suck.

I'm replacing the horrid TBI heads on my crate 350 with Vortec heads, along with a complete rebuild of the entire drivetrain. Upgrade from the ZZ4 cam to LT4 hot cam, mildly pocket port the heads, new performer Vortec intake, 1.6 roller tips, and TES headers to replace the manifolds. Heads have been machined for bigger springs and have the screw-in studs from my ZZ4 heads on them.

My problem is I have a comp # 941 valve spring kit on my shelf for my 383 with the ported ZZ4 heads, but I remembered I have the stock ZZ4/LT4 valve springs that came off them. Low mileage of course. I was thinking of putting those ZZ4 springs on my Vortec 350, but I've heard max lift is .520" and also .525" lift. I'm nervous because lift with the 1.6 rocker is .525", at or just over max lift. Anybody running an LT4 hot cam kit with ZZ4/LT4 springs, or know if it'll work ok? And can anyone confirm what the max lift is of the springs?

Oh yeah, I got a bigger radiator too

 

i wouldn't run any springs from gmpp or k motion. look in the comp or lunati catalogs for something to match your cam

 

I agree completely. Don't cheap out on valve springs, the pain-to-$$$$ ratio is way too high.

Call Comp or Lunati or Crane or Ultradyne, get their recommendations for springs for a .525" cam, and follow them. You'll find that all of them will recommend a 1.45" spring or a conical one; none will spec a 1.25" diameter spring like GM does. And theirs work reliably over hundreds of thousands of miles, GM's don't.

 

Yeah, I know they aren't the best valvesprings, that's why I have that set of comp's I'm reluctant to use because I want them for my 383. At best these'll be a temporary set...I know it's more work but I don't mind since I have a toolbox full of tools at work. I just wanna know if they'll work or not. Anyone?

 

to answer your question. you are installing the lt4 cam. in the zz4 heads are the lt4 springs. so they will be fine. why wouldn't they work? they were designed for the lt4 cam with 1.6 rockers.

 

hahahaha, who makes the springs for GMPP? They'll be fine. The ZZ4 springs are the same ones that come in the hot cam kit.

 

Yes, they are LT4 springs, but I'm not installing the standard LT4 motor cam, I'm installing the LT4 hot cam. I'm assuming they'd work since I found out max lift is .525", which is exactly my lift with that cam and a 1.6 rocker arm. So in a way, it was a dumb question, but since it comes down to a question of which cam we're referring to, it doesn't hurt to be sure.

Looks like they'll BARELY work. Anyone done this?

 

Cool =) Looks like those'll be going on my Vortec heads then. I'd like to have my Comp 941's on there, but I'm saving those for my 'performance' engine. hehehe. Thanks for all your help guys!

 

just looked in the GMPP book. the lt4 hot cam springs are the same as the zz4 springs. . 12551483