I have a 340,rebuilt to 71 specs. Looking to upgrade to an XE274 cam kit. The website says the heads will need machining to make it work. I called Comp and I could not get a straight answer out of the guy on if i really needed to do this. Once and for all, what will it take to make this cam work in my motor?

Thanks

The recommended springs for the cam are double springs which will require machining to make them fit.

Thanks for the input. How much $$$ on average would that machine work run me?

I agree, thats not that big of cam, let me check what springs I run on my stocker and get back to you

Thanks. I'm all about preventative maintenance, but if I don't actually need the double springs that require machining, then that would save time and $$$.

what problems exactly? + FYI.. engineers arn't always the brightest pee in the POD.

IMO, depends on how hard you plan on turning it.

If you don't plan on anything over 5500, then a stout single spring will work.

Running it to the max RPM, put the double 995 spring on it. I just ran into this very decision. I have 3 choices, 484, XE274, XE275HL. The first two you could get away with a stout single and run it easy. Plan on turning it 6K+, a single may control it, but why chance it. Brian at IMM and I had a pretty lengthy talk about this. He had nothing to gain from going either way and strongly suggested the double spring set up.

Machine the heads, drop on a locator and you have one less potential issue to worry about.
Do it once, do it right!

I'd guess about $100 for cutting the guide/spring seats and locators.

My 340 has an XE274.

$120 at my machine shop a couple years ago. Worth it for peace of mind, plus I regularly turn it to 6,200 rpm at the track, when it stops pulling. If I had to baby it because of the springs that would take a lot of fun out of it, lol. My opinion, I would do it and not worry about it anymore.

I get my best ET and MPH at 6,200. I've tried every shift point starting at 5,300 and worked my way up. I've made several hundred passes so I know the engine and the car very well.

Comp likes lots of pressure on thier lobes. It's for a reason, and ropm is only part of it. The XE268 is fine with singles. Anything larger should have double springs. Saying "I did it and it worked" is as good as claiming the engineers are clueless. Why put in a cam you can't make use of because the springs and rpoer setup are too much $$? Cutting the guide tops and spring seats as part of a valve job is usually a metter of $100-150. If they have to pull them apart, do it, wash it, and replace the seals, and assemble, it will be more. And, expect to get the retainers and locks to match teh spring. Again, there's one right way, and million other ways that might work.

This peaks my curiosity. I'm running the 274 in my 360 with single springs. I've got Eddie heads and the springs that came with them were rated just over .500" of lift (bought them assembled), so I didn't give it anymore thought. Am I asking for trouble??

see ya added a jeep to your collection, how ya like it?

buy the way, yes on the springs and head work, or go EDDY.