Cam and Springs question

nirvevo · Sep 19, 2009, 06:50 AM

OK, given an equal rev limit (say 7800 rpm), would the stock valve springs actually have a higher load and at least as fast of a recovery rate with a 272 cam as it does with the smaller stock cam, since it is not traveling as far as it does with a smaller cam?

It seems that the spring tension would actually increase with a larger cam, all else being equal.

Street Arsenal · Oct 14, 2009, 10:59 PM

In short the 272's are punishing the stock springs more than the factory 248's. If you're only playing with the 7k redline your safe. That's what the springs can handle without failure.

MitsuJoe · Oct 15, 2009, 10:21 AM

Which 272 cam?

Evo8N00bie · Oct 28, 2009, 09:49 PM

mmm... interested

nirvevo · Oct 29, 2009, 06:48 AM

I have since learned a a little about spring rates and bind specs etc... not a lot, but enought to know it's necessary to match your cam lifts and duration to the appropriately spec'd spring.

I know that some guys have kept their OEM Evo valve springs when they put Kelfor 272's in, but most are restricting their rev's to 7800. (as will I)

One thread talked about the springs showing a drop in clamping after use. I wonder how much of a drop off in spring performance various brands have?

I am going with FP Beehives for a few reasons.
1. Double springs put a heavier load on other valve train components, my build doesn't require them so why do that.
2. The argument about beehive design is a worthy consideration.
3. Titanium retainers are more brittle that the OEM's - longevity issue - I won't be dealing with that issue this way.
4. I like FP's R&D and recommendations. in general.
5. Valve springs are not forever, I will likely revisit the issue when a rebuild becomes necessary. I hope to be done for a while after this. (famous last words)