Im putting together a parts list for my cc503 swap and im second guessing my spring choice (PAC 1218/1518).

Ive helped a few of my LS1 buddies do cam swaps and they have all used dual springs instead of the beehives im looking at. All of their cars dont seem to mind 6800 rpm one bit.

Is there a benefit to dual springs? I want a SOLID valvetrain, im not cheaping on stuff. I want a valvetrain than can take 7k rpms, even though i dont plan to spin my stock bottom end that high. I want every bit of reliability and power i can get.

I did some searching and i dont see many people using dual springs, nor could i find any comparisons.

 

Its going to depend on who you ask.

Everyone that has behives swear by them....I would never run a set, I have used manley,K-motion and REV valve springs and never had an issue with springs. My last set-up was K-motion and I was shifting 6900 and going through at 7200

 

no one else? I thought id get more opinions on this... at least id really like to.

 

I also use dual Crane springs, and I have no issues in the 6800-7000k range.

 

Are you having machine work done to the heads?

I looked at using the CC 987 dual spring when I replaced my valvetrain, but ended up going with the CC 26918 beehive instead due to possible valve seal contact by the 987's inner spring, and also due to the spring pressures involved with each spring. I was told the guides would need machining to use the 987 dual spring.

Not sure if this is true, but I went with the beehives to be sure and haven't had an issue.

FYI: Only spinning to 6200 rpm on a stock bottom end

Thomas.

 

I like the beehives with my Comp XFI-292 HR! I currently have the Comp 918s, but I'm upgrading to PAC-1518s w/ new titanium retainers. I have the new springs and retainers, just haven't had to time to get them installed and adjusted. If it was race season and could go to the track, I would be more motivated.

WD

 

I have a small Joe O. cam, 222/226, and the 987s could not keep up. Granted the design of the lobe has a bearing on this, but even people in the know thought the 987s would be up to the task. The 918s solved my valve float that was happening at 6k. The motor doesn't make any more power, but doesn't fall on its face now at 6k. Instead it only loses about 15 to 20 hp by 6500rpm, and my shift points are now 6300 to 6400. Cut almost half a second off my 1/4 mile et.

 

Im not planning on doing any machining, heads will not be coming off the car.

what hardware are you using with your 1518s? I just have the basic comp stuff everyone uses with 918s on my spreadsheet, but ive been wondering if there is better.

interesting.

 

I bought the Comp brand titanium retainers w/ 10 degree locks (currently running the Comp Steel retainers) to go with the new PAC-1518s. Also, I have Crane custom length 3/8" push-rods and Crane Gold Race 1.6 RRs. I would like to upgrade to shaft rockers in the future (Jesel). I also bought a Comp beehive mic to re-check the installed heights on each valve when I change out the springs and retainers.

This will be a "heads-on" spring change, which I've done before. Currently, I'm falling off in power in 3rd gear as I approach the stripe at the 6500 RPM range (loosing MPH). And, float the valves if I don't let-off immediately when crossing the 1/4 stripe. I hope the new PACs and titanium retainers fix this issue.

WD