Heavy Duty Z28 Valve Springs - Third Generation F-Body Message Boards

Max · 01-07-2007, 10:48 PM

I'm trying to choose a new set of valve springs.

Based on advice I got from the Crane Cams website, I'm shooting for 120-145 lbs. of seat pressure and 300-360 lbs. of open pressure. My engine setup is detailed in my sig.

I found this set of springs and I wanted to get some opinions:

Heavy Duty Z28 Springs

They are rated at 130 lbs. at 1.8" installed height and 350 lbs. at 1.2" open. Most other 1.25" OD springs fall short of these pressures.

Do you think these are a good choice for my application? Will my pressed in rocker studs withstand the additional stress?

Sonix · 01-08-2007, 12:50 AM

What cam are you planning on running?

I've noticed that almost all 1.25" valve springs have pretty similar spring forces, which is understandable given that they'll all be pretty much the same dimensions - and that's roughly 110/300. Depending on how they measure it, they can "round up" or be realistic.

130/350 is a commonly used spring force, and goes hand in hand with 1.45" dual springs like the comp986's. If you use these springs that you're looking at, i'd measure the spring force myself. Your local engine builder can probably do it for you.

Oh yes, you definately do NOT want to use your pressed in studs for this. Pin them, or pull them and use non-collared threaded ones, or go all out and use collared ones (machining the heads of course...)

cc 82Z-28 · 01-08-2007, 06:49 PM

I have used those with no problems..

Damon · 01-08-2007, 08:31 PM

Also check out the Crane 99846 springs. They're right in line with what you're looking for.

Max · 01-09-2007, 01:23 PM

Thanks for the advice on the Crane springs but I ordered the ones from my original post yesterday. I got the springs, chrome moly retainers, and new locks for $90 plus shipping.

I asked an engine builder at my local machine shop as well as a technical advisor at Scoggin-Dickey if I would need to use screw in studs with these heavier springs and they both advised me that with the mild .450" lift of my LT1 cam I should be fine with my pressed in studs.

The screw in studs would be nice to have but to me the extra work and expense are not worth it. I just hope they don't pull out on me.

D's89IROCZ · 01-09-2007, 01:37 PM

Iam currently running them springs . SD1007 . They told me the spces were 120lbs @ 1.8" iustalled height and 350 lbs @ 1.2" I am currently useing them on a ZZ4 cmashaft. Works great.

Mkos1980 · 01-09-2007, 01:53 PM

I would go with the comp 918 beehives. I would set them up at around 1.77-1.8

D's89IROCZ · 01-09-2007, 02:32 PM

Are they stock diameter ? With the SD1007 , you don't need to cut the seats for bigger springs.

sofakingdom · 01-09-2007, 03:11 PM

For a little teeny cam with typical stock lazy ramps, like the LT1 cam (any of the several LT1 cams for that matter), those weenie stock GM springs will be fine. For about any aftermarket cam beyond the "RV cam"/"Performer"/"MTC-1", they are inadequate.