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LB9/L98 valve springs, anyone know their pressure roughly? cheap stock valvetrain

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Old 09-12-2010, 05:04 PM
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Car: 89 Firebird Formula
Engine: 305 Vortec, Single-plane, 4 barrel
Transmission: T5, soon 700R4
Axle/Gears: 88 10 Bolt, Disc, Auburn, 3.23
LB9/L98 valve springs, anyone know their pressure roughly? cheap stock valvetrain

I got some EngineQuest aftermarket Vortec castings, new, on eBay from the mfr for $220 (for BOTH!!!!), came with screw in stud set aswell, and machined for pre-87 intake pattern, also the guide boss is cut down a bit to I think it was about .800.....

Anyway, amazing deal really but - street driven LB9 305 motor... looking to get best bang for the buck so, I was planning to assemble the heads with Manley street budget performance valves... and everything else the stock junk. I would get different springs at least but - serious budget! , not looking to go past 6k rpms, and would like to get 1.6 ratio roller rockers in a year or so.

Does anyone know a rough guess on the spring pressure? known failures? (ie: maybe I should replace the valve stem locks! lol) Are the stock Vortec springs weaker or about the same? (I don't have any but just a thought)

As much as I would love to go with guideplates... then I would need pushrods, guideplates, rockers... of course once upon a time I threw this stuff away thinking I didn't need more spare parts otherwise I would go that route for the cost of degreaser

What are your thoughts? I say I am on a light budget.. truth is I have money but I also have a girlfriend... I just ordered hedman 68460 headers, a carter electric fuel pump, and picked up a 700r4..... she hasn't killed me.............yet!

Any suggestions for good cheap parts are welcome! I was looking at $30 elgin or similar valvesprings on eBay 110 closed, 320-ish open hmm...

EDIT: BTW should have added that I had TPI but I am using a single-plane with a holley now, I will use the 305 block until more money comes into play.

Last edited by PV9685; 09-12-2010 at 06:05 PM.
Old 09-12-2010, 06:29 PM
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Re: LB9/L98 valve springs, anyone know their pressure roughly? cheap stock valvetrain

Stock valve springs are only about 70# on the seat, 220# over the nose. Not very strong springs. Those cheapies (or inexpensive ebay "Z28" springs) will work fine if you remove the inner dampener coil (won't clear the wide foot of the Vortec valve guides).

Stock valves, locks and retainers are all fine for a budget performance build. So are stock self-aligning rockers. Screw in studs are often shunned for any performance application but the reality is that having them pull out is actually exceedingly rare and usually occurs as the result of severe over-revving (valve float) or binding somewhere in the valvetrain (inadequare clearance somewhere for your cam's lift). All you need for what you're doing is better springs than stock.
Old 09-12-2010, 06:33 PM
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Car: 89 Firebird Formula
Engine: 305 Vortec, Single-plane, 4 barrel
Transmission: T5, soon 700R4
Axle/Gears: 88 10 Bolt, Disc, Auburn, 3.23
Re: LB9/L98 valve springs, anyone know their pressure roughly? cheap stock valvetrain

wow that's just as weak as the springs that come on Vortec heads, right? Well, leave it to GM If those numbers are roughly accurate I wouldn't feel safe going over 5k rpms! lol
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