Max

Since swapping in my LT1 cam and converting to carb for ease of tunning, my stock valvesprings are now the weak link in my set up. I'm planning to upgrade and have searched extensively but I still have a few questions.

Has anyone used the stock replacement LS1 or LS6 beehive style springs (OD 1.29") in stock 081 castings (1.25" spring pockets) without machining the heads. I don't think they would fit but correct me if I'm wrong.

Otherwise, I read an article on the Crane Cams website that says that roller lifter equipped motors which are run above 4500 RPM need between 120-140 lbs. of seat pressure and between 300-360 lbs. open pressure.

The only reasonably priced set of springs I have found that come close to these pressures are the Crane Cams Blue Racer valve springs pn: wg2620. They spec out at: 1.255" OD / seat pressure: 114 lbs. at 1.7" / open pressure: 340lbs. at 1.2" / coil bind at 1.153" / Spring Rate 432 lbs./inch

These springs have a higher rate than the Z28 HP and the Comp Cams 981 springs that are mentioned so often on thirdgen.org

I think the Blue Racer springs would be a good choice my only concern is whether or not the pressed in studs will stay in place with the relatively high spring rate.

V8Astro Captain

iTrader: (1)

Personally I'd run the Comp 981 springs. The mellow ramp of the LT1 cam isn't going to throw a lifter off the cam with a 981 spring. I've run these springs in a couple different engines. Most of them with specs close to the LT1 cam.

Right now I'm running an LT4 cam with 983 springs under a blower. No problems up to 5500 rpm...

Max

Thanks for the reply. I think your right, either the Blue Racer Springs or the 981 springs should be able to keep the lifters from lofting too much. I'm a little more concerned with the valves bouncing of their seats when returning to the closed position due to a lack of seat pressure. I think that's the problem I have now because power seems to drop off above 5000 rpm and the LT1 cam is good for more than that.

I should probably be shifting somewhere around 6000 rpm and I'd like to be able to rev safely up to at least 6500 rpm without valve float and without breaking parts.

Does anyone have any experience with the 1.29" OD LS1 or LS6 valvesprings. Can someone tell me the maximum rpm a stock LO3 bottom end can withstand on a regular basis?