I am about to order this for my cc306 cam (.540 lift, BUT I also have 1.6 roller rockers) here is the part number at thunderracing.. 40-10308-1 ... Crane Aluminum Head LT1 Spring & Retainer Kit, set of 16. I have heard on here before that this will work, but want to double check... thanks!!!

 

Those springs should work just fine.

Note that they have a very high open pressure (425lbs?) at the prescribed install height. I've always wondered if that strong of spring would lead to premature wear of the cam and lifters. Any thoughts on this from others with this popular spring set?

The reason I bring this up is that the Comp recommended spring for most of their XE cams and perhaps the 306 has a open pressure of like 280lbs! (I don't have my Comp catalog handy so my numbers may not be exact.) Those Crane springs are a big step up in spring pressure!

 

thanks for your help ... If anyone has had any problems with that, let me know.

 

I agree, I'm no expert, but am concerned about such a huge jump in spring pressure and what the down side might be.

 

I wrote a brief "Tech Tips" on valve springs that may be helpful. Go to http://www.kennedysdynotune.com/ and click on "Tech Tips" at the bottom of in the left hand menu bar. Once you get to "Tech Tips", click on the link to "Valve Spring Tech".

Rich Krause

 

I hav em on a 306 and I like em. They keep the valves closed nicely, and make for easy setting of lash. Plus, i don't have to worry about them breaking under load. I'd rather collapse a lifter than shatter a valve spring, and drop a valve..

 

I have this setup on my car and it works fine.

 

Nice article. If I read your tech article correctly, these Crane dual springs will lead to remature wear of the cam and lifters. After reading your article I feel like I want to remove that spring set!!

What is interesting is that Crane recommends this extremely stiff spring set for its nice but mild 210/224/112 steet cam.

 

What are the specs on the springs?

Rich Krause

 

Rich, this is the spring (99893) that Crane recommends for their LT1 cams.

The OD of outer is 1.46"/seat pressure at installed height (1.75") is 165#/open pressure is 426# @1.110/ average spring rate is 408#/bind is at 1.080.

Upon recommendation I went with this spring set when I recently redid my top end and replaced the Crane 2033 cam with my present Comp XE 502 (218/224/112). After reading your article I am having second thoughts that this spring set will wear out my top end hardware in short order. Boy, I am not excited about doing another spring job.

What's your thoughts?

 

I dunno, that's a lot of spring for that cam. Do you have good quality rockers and pushrods? How high are you going to rev it? A spring with ~125-135lb on the seat and 275-300lb at 0.500 lift would work fine. But if it's already installed and you have good quality components I can't say it's necessary to change it. Comp recommends the #986 for the 502 cam. It's 132lbs @ 1.750" and 280lbs @ 1.200".

Rich Krause

 

Thanks for your reply, Rich.

To my belief I have quality components in the valve train. I have Crower 1.6 ss rollers and private label MORE Performance push rods. The valves are REV ss and the lifters are Comp 850s.

I don't drive the car hard and I don't take it to the tract. My rev limiter is set at 6200. If I had it to do over again, I'd probably would have just gone with the Comp recommended spring as you mentioned above. The Comp cam is forged and not billet and doesn't have high lift even with the 1.6s. So I hope I'll be o.k.

I do respect and appreciate your advice.