In all seriousness could you shed some light on this?? I mean i do understand that concept with ALOT of things. And common sense should tell you you dont need a massive spring rate for a baby cam. Im purely asking for technical purposes and to improve my own understanding

 

The 243s I bought are off of (i believe) a Trailblazer SS. I actually source them from a local salvage yard for a good price. When I checked their online inventory they showed to fit a TB SS or an 05-06 Corvette 6.0. When I went to pick them up I fully expected to see a 799 casting # but was surprised to see they were 243 heads. I don't know if these have the sodium filled valves as not all 243s came with them. Either way I will be better off running these than the 853s my car has on it now. If anything, I will have .5 bump in compression.
I have decided to go with the PAK 1518 springs that are available with the kit for an extra $50.
Thanks again for the advice!

 

Man I was looking at PAC springs on their site and the strongest beehive spring I saw was 425lbs open load and I dont think that was a LS1 specific spring. Wow! You guys are really flirting with valvefloat. I would deffinately never install a spring under 400lbs open on my car, thats asking for trouble. Under 450 would have me nervous. Thats why I buy springs based on dimensions and specs because all thses "LS specific" springs are pretty weak. I can guarentee a ton of guys, if they drive hard enough, have valve float issues at high rpms. I guess for cruise only duty some of these will do but not for me.

 

Wow answers are all over the board....

 

Sorry man, I just stated a prsonal view based on what Ive seen and used. Ive had the valvefloat issues with some of the LS springs that are out there. I was told Patriot Gold Extremes were some of the best and I saw valvefloat with them and those are rated at 410lbs open. But, all dependes their application. I rev to 7k rpms with a very light forged rotating assembly that spins up very fast, thanks to 12:1cr, so my springs will see a bit more "abuse" if you will since I drag and track the car often. Some guys dont really race or rev that high and so they wont really see issues with some of these springs.

 

I appreciate your input. My application is not as wild as yours. I'm running the stock bottom end, very mild porting on otherwise stock 243 heads @ 10.5:1 comp. The cam has .597-.598 lift and 222/226 duration from EPS. I don't track the car at all and the car very rarely sees 5000 rpm.

 

Well if u plan to keep the car like that and if the track bug dont bite you then a good quality valvespring will get the job done.

 

The 2011 PAC catalog shows some new dual springs for the LS engines. They are PAC 1204, 1205, 1206, 1207, 1208 & 1209 - max lift from 0.700 to 0.750" depending on which model. Open loads range from 385 lbs to 510 lbs at around 1.100" ... so these might be good depending how nuts you wanna get.

They also show new beehive springs (1219 & 1519) that have 363 lbs @ 1.175".

 

Didnt see those but those doubles sound a lot better. 450-510lbs is more like it.

 

I'm not totally educated on "valve float" ... but if a spring like the PAC 1518 is rated for 0.650" lift, I would think that PAC knows that spring will be used on a semi-radical cam and should be able to take it without causing valve float. I'm I wrong in this thinking?

I'm currently installing PAC 1518s in my stock Z06, which of course doesn't have that radical of a cam so I'm sure the 1518s are near over-kill for my application. I'm installing them for increased reliability more than anything over the questionable yellow OEM springs.

Also, I would think using a super heavy spring would probably be harder on the valve seats and take its toll after awhile (?).

 

Well we arent talking about 700-1000lbs springs here either. Lift, coil bind and install height is one thing, pressure holding the valves open and closed are another. Also some cams can have more lift without being too radical. A 500lbs spring wont beat up a valve seat if the the geometry and setup is correct. Another thing that can cause or contribute to valvefloat is rocker weight and geometry. Another reason I switched to a lighter Yella Terra setup vs Harland Sharps that I felt were on the heavy side. Still, Im spinning my setup to 6500-7000rpms with a fast spinning setup so Im sure my needs would be different than most other guys. When I think of parts I automaticaly leans towards the max setup. So, where some of these springs would be great for some guys here, they would have me concerned i guess you can say. Even if i wont do a certain thing with my car, I want to know that i can. Example, I look for tires rated for 200mph yet Ive never been 200 and who knows if I ever will but i feel better knowing my car can, in theory, go there. Lol. Thats just how I think. I know some vendors and shop may disagree with my opinion on springs, especially if they sell them, but Im going off what Ive seen on many street cars and at the track.

 

Then they were the wrong springs. Fact is beehives control the valves better than dual springs...

OP buy a quality set of beehives. My PSI 1511 maxlife beehives have been working great and you can use the stock hardware with them. They are $250 but have a long change interval.

 

Maybe but according to the owners they were some of "the best" LS specific springs. Just sayn