VALVE SPRING EXPERTS advice appreciated

[BLACKHAWK38]

I want to have the valve springs changed on my GN, it is a stock motor , untouched cam, heads, ect,

What spings do I need?

Will 100-110 pound springs wear out the cam faster?

LT-one gm 350 v8 springs ? stock gm or comp or crane or any aftermarket?

Valve seals, do I need them,

retainers?

I am a real dumb bell in this area!

Please reply
Regards<> Blackhawk38

[ijames]

The LT1 springs (old 302, not the new LT1 350) are 100-105 lbs seat force, which is way more than you need with a stock cam. Lots of guys are happy with the CompCams stock replacement 979 springs or the 980's which are about 5 lbs more seat force. You should be able to reuse your retainers and keepers (just don't let any keepers fly away :-)). If you are not getting a puff of blue smoke on a cold startup I'd leave the valve seals alone, but that also kind of depends on engine mileage.

[gofstbuick]

Actually, I understood the real old LT1 or Z/28 valve springs to be just regular production valve springs. The new LT1 valve spring has 101 closed pressure at 1.78 installed height. I'm using the Chevrolet second racing design camshaft valve spring (3927142). That spring is closer to what many think is the early Z/28 valve spring. It is 110 closed pressure at 1.7 installed height, with a 358 pound rate. A very heavy valve spring. I'm using a Poston 107T cam (according to Lunati, an exact match of their cam, except 4 degrees of advance and a technician at Lunati confirm they used to make cams for Poston). But the recommended spring for my cam is 108 close pressure with 350 spring rate. So my springs very closely match the requirements for the camshaft I'm using. My engine is needs to be rebuilt (long story), but my cam bearings are trashed (1 to 3). The cam has 45000 miles on it and the lobes measure perfect. Assuming the cam is straght and the engine needs new cam bearings, I will reinstall this cam and run those same valve springs. The factory Buick spring requires 78 (-/+ 4) pounds closed pressure and the closest valve spring to those specifications is the Compcams 979 or 980. IMHO that would be my valve spring choice for the factory cam. The heavier spring may accelerate wear and I would hate to advise you to install the heavier spring only to hear you need to tear your engine down because of premature cam wear. I think these engines are less forgiving on excessive spring pressure than a SBC. The valve springs in my engine very closely match the cam requirements.

[BLACKHAWK38]

Originally posted by gofstbuick
Actually, I understood the real old LT1 or Z/28 valve springs to be just regular production valve springs. The new LT1 valve spring has 101 closed pressure at 1.78 installed height. I'm using the Chevrolet second racing design camshaft valve spring (3927142). That spring is closer to what many think is the early Z/28 valve spring. It is 110 closed pressure at 1.7 installed height, with a 358 pound rate. A very heavy valve spring. I'm using a Poston 107T cam (according to Lunati, an exact match of their cam, except 4 degrees of advance and a technician at Lunati confirm they used to make cams for Poston). But the recommended spring for my cam is 108 close pressure with 350 spring rate. So my springs very closely match the requirements for the camshaft I'm using. My engine is needs to be rebuilt (long story), but my cam bearings are trashed (1 to 3). The cam has 45000 miles on it and the lobes measure perfect. Assuming the cam is straght and the engine needs new cam bearings, I will reinstall this cam and run those same valve springs. The factory Buick spring requires 78 (-/+ 4) pounds closed pressure and the closest valve spring to those specifications is the Compcams 979 or 980. IMHO that would be my valve spring choice for the factory cam. The heavier spring may accelerate wear and I would hate to advise you to install the heavier spring only to hear you need to tear your engine down because of premature cam wear. I think these engines are less forgiving on excessive spring pressure than a SBC. The valve springs in my engine very closely match the cam requirements.

MY 87 GN CAR HAS about 13,000 miles on it, I have also (2) turbo Riviera's , one of which has oringal factory springs

The valve spring for the Riviera is 93 lb closed pressure(gm 25512551) VS the GN 78 lb stock spring(GM 25517605)

I SEE THAT jegs and summit have the comp 979 and 980 springs. BUT maybe I should use the GM 93 lb spring?

NO smoke anywhere, SO keep stem seals?


Regards, blackhawk38

[XLR8]

Comp Cams 980's - wiothout reusing the spring cups - worked well for me.

[JeremysGN]

While you all are discussing springs, I have a Precision 218/218 cam and I need to know where to find springs. I called precision and they said I need 100-110 seat and no more than 300 open. I've checked Jegs, Summit, and every where else but no one has anything less than 350 seat pressure. Any advice. THANKS

[gofstbuick]

Gm list a spring for the 3.4 liter chev engine. Part number 12363215 and retainer 12363216. It is rated at 105 @ 1.7 installed height and 296 open pressure.