So I'm buying a Vette L98 and am puttin in the LT4 HOT. So I need new springs but don't want to have the heads machined for wider springs. What diameter are the vette L98 valve springs? I've heard that they're bigger than the iron L98's. How big of a spring will fit on w/out machining?

I'm just gettin into this so I don't know too much. What do I need as far as shims and the like? I've heard you need to get shims to keep the spring from rubbing the head away cuz it's Al. Besides that shim do I need more to raise the spring up? How do I know how much I need? Do I need the heads machined to accept the shims or do they come in the same size as the springs?

http://www.competitionproducts.com/page24.html
Will the LT1 or "2300" springs in the above link work w/out mods on a stock vette l98?

That's it.... for now. Thanks.

 

Comrade,

You should be able to fit any 1.250 diameter single spring in a stock 350 SBC head. Installation height should be 1.700-1.710" with standard length valves. Subtract the coil bind height from that number, then subtract at least another 0.050-0.060" margin for safety and you should be able to determine the maximum lift the springs will handle with any reliability.

You will also want to discard your original retainers and NEED to discard your exhaust valve rotators and install a lightweight set of retainers that fits the springs. This would be a great time to install screwed studs to handle the extra pressure of the better springs. Of course, valve seals are a given. You should be able to complete all of this work with the heads on the engine unless you intend to use push rod guide plates. Personally, I'd go with the Comp 1317 or 1318 rockers - they are smaller, lighter, and stronger than any other rocker and don't need the guide plates that get in the way.

 

Thanks Vader.
Pardon my ignorance but I’m learning as we go here and am not quite clear on everything you said. Even if the new springs are the same diameter as old I should get new retainers? Is this because the new ones are stronger? What are valve rotators? Don't the aluminum L98 heads have screwed studs from the factory? I’m also assuming I need to get my valve guides milled down to clear the retainers, do I need to pull the heads for this so the valves can be taken out so they don’t interfere with the milling? Will I need pushrod guide plates with the stock rockers? Thanks again.

 

use a set of spring cups too, to protect te heads