408 cam selection - New Information Please come inside!!

[SCIV]

I ran my old cam with the 918s and it was not an issue at almost .610 lift.

What max RPM?

[RedHeartbeat]

6500 is where mine was set

[2k5Squirrel]

how about my stock 4.8 turning 6700 RPM's...should i change my chit or don't worry about cause it's a lil 4.8

[SCIV]

I think the 4.8 might make a difference. But what do I know, I am on here asking questions like crazy.

[2k5Squirrel]

I think the 4.8 might make a difference. But what do I know, I am on here asking questions like crazy.

got it brother....that's a lot of money. don't want to mess it up going to the 7-11 for a slurpee

[carfreak07]

FWIW, Erik at HKE says to run the springs shimmed close to coil bind. He expressed concerns about my Patriot springs and is shimming the springs up .060" to the way he prefers them. He told me that if I were to ever replace the heads, contact the manufacturer of the head and tell them how much lift I planned on running so that the springs could be setup to their specs. He recommended not buying off the shelf heads unless you're going to have them shimmed properly. I think he said that he likes them shimmed within .050" of coil bind.

that sounds right!!!!

.050 from coil bind, this is extremely safe. But you can only shim tighter, unless he cuts the spring pockets to let them drop down....this being said....918's are good for .600 and the cam he wants is .602 or something so that means he is in coil bind by .002.....when turning high rpm's, something could very well break!!


SCIV
If you are dead set on running the 918's then I would stay at .588 or lower, if you are wanting to run the .602 lift then I would definately go with a double spring capable of .640 or .650. The key here is to help you from breaking something. I have built several engines and all to which I wanted to be able to beat the crap out of and luckily I have been successful. Allen did say that he would run the 918's on a big cam but he didnt say anything about exceding the max lift that the springs were capable of. They are a great spring and I went with them myself...my cam is a 228/230 585/585 on a 112.

I know this is just a forum and its hard to take advice from people so you can decide what you want to do, but either way I hope I helped you out. Your springs will also stay stronger longer if you arent at the max lift of the spring.


Hope that all made sense, shoot me an email and I can give you my telephone number. maybe I cqan help you out over the phone. jasdan86@hotmail.com

[SCIV]

Thanks everyone.

I am leaning towards a 228/232 .585/.588 112

[carfreak07]

Thanks everyone.

I am leaning towards a 228/232 .585/.588 112

that sonds like a winner.......You will like being able to purchase the affordable 918's with that as well. That is almost identical to my cam, it seems to be really drivable and have a real nice lope. I dont feel the cam as im driving at 60 like i thought i would. Hope you like it to.

jarrod

[1slow01z71]

Shimming the springs puts more tension on them. As you shim the spring more the stiffer it gets, so shimming it as close as possible to the maximum compression point of the spring puts the maximum amount of tension on the spring to prevetn valve float. The bad thing about doing that is that it wears out sprigns faster and causes a slight loss in HP due to valvetrain friction. Also carfreak before you post stuff about these springs make sure your facts are straight and scare SC into thinking he has the wrong springs for his cam. By doing the calcs with the info provided I get on Comps website I get a theoretical coil bind of .638". Now you wouldnt want to run it that close due to lifter hop(possible), coil deformation(@high rpm), and lifter plunger movement. Even on TSPs website it says .625 lift which would be about right when you factor in everything I listed above. Here is the link
Comp Cams "918" Stock-Diameter Replacement Springs
SC, I think the 228/232 cam is better decision lift aside, it will net you a very nice driving truck and will come out of the hole HARD on a 3K stall.

[carfreak07]

Shimming the springs puts more tension on them. As you shim the spring more the stiffer it gets, so shimming it as close as possible to the maximum compression point of the spring puts the maximum amount of tension on the spring to prevetn valve float. The bad thing about doing that is that it wears out sprigns faster and causes a slight loss in HP due to valvetrain friction. Also carfreak before you post stuff about these springs make sure your facts are straight and scare SC into thinking he has the wrong springs for his cam. By doing the calcs with the info provided I get on Comps website I get a theoretical coil bind of .638". Now you wouldnt want to run it that close due to lifter hop(possible), coil deformation(@high rpm), and lifter plunger movement. Even on TSPs website it says .625 lift which would be about right when you factor in everything I listed above. Here is the link
Comp Cams "918" Stock-Diameter Replacement Springs
SC, I think the 228/232 cam is better decision lift aside, it will net you a very nice driving truck and will come out of the hole HARD on a 3K stall.

you said get my facts strait but you stated the same things I did!!! Maybe you should read my comments a little closer....pushing the springs to their limit is hard on the valvetrain just as we both stated....i was quting someone else's opinion on shimming the springs...so before you go bashing on me maybe you should read a little closer!