If I were you I would rethink my choice of everything.....doesn't sound like you need a cam, except maybe a Thundersticks sidecar cam....they pull like a train low and mid range....but seriously....why not leave it standard?

 

I can't really say much about any cam other than the one I put in mine which is the rumblestick made by Headquarters. The guys at headquarters juice up motors for a living and there damn good at it. This is the candian site http://www.head-quarters.com/

 

Pistons are only one part of the C/R formula. The other part is combustion chember.gasket, deck height. Some people put in 10.5 pistons and get away with it because they have more deckheight, thicker gaskets, and larger combustion chambers. The Harley combustion chambers are "usually" larger than they are supposed to be. Some vary quite a bit from front to rear which should be corrected.
So in closing I just want to say if you do not have your heads cc'ed then you probably don't have the compression ratio that you think you have.

 

My evo allready had an EV27 in when I tore it down last winter, orderd 10:1 pistons, then I got cold feet, and ended up milling them down to around 9,5:1 . 10,000 miles later and it's still running stong as ever, big differece form the stock pistons.
When I researched the ev27 back then, people were saying there great in a stock motor,(and it was) but they really come to life at compesion ratio's 9,5 and up.(it did)
Had I gone 10:1 or higher, I think I would have had to upgrade my Dana S ingnition to a digital system to make it work.

 

Well FOR SURE I AM having my heads freshened up before they go back on. So when I finally get around to ordering things I will keep that in mind.

Spanners, although your suggestion would be easiest, I've got my whole engine apart and all I'm going to do is return it to stock specsNOT HARDLEY.......what would the fun be in that? I do want it to be something more than what it was before the lifter went out. I'm just trying to figure what would be the best for my specific riding style and needs. I'm realizing that there probably isn't ONE magic combo, there are MANY. I just have to find the one that is best for ME. I'm not giving up, now that I have probably a year to get it all back together again. I can just keep researching and asking questions. And whenl the time comes to start ordering parts, I pray that I will have figured it out.

 

Then go for the EV27 and an ign module for starters, gas will only get more crappy so keep it below 9.5:1 and grab some V&H pipes and while you are at it...a head job (which is different from a blow job) will give you a motor that revs and breathes nicely and works on ***** gas....and is reliable!

 

i have got the same combo that you speak of on my 1998 ultra classic. wiseco 10:1 .020 over with a ev-27 mine is EFI with a dynojet pcIII, arlen ness big sucker and bored out OEM exhaust with true duals. i have never been happier! if your rebuilding from stock you will be amazed at the seat of the pants hp difference. i think you may be reading into it more than what is needed. i would recommend adjustable pushrods that way down the road when it is affordable to you, you can try another cam of a different grind if you choose. the motor will run fine.

 

Thanks for the input! Mine is a 92 so it's a case breather, S&S E carb'd model so I'm not sure if I would have as much tuneability as your EFI'd set up. But it's good to hear that you have the same pistons and the EV-27 and it runs GOOD. Mine will be a from stock rebuild and I will FOR SURE be installing adjustable push rods. I know the butt dyno numbers will be to the roof from how she ran after 55K hard miles........

 

Go with the EV-13, that's what I have in my bike. Comes on sooner.

Bob
97 Heritage

 

Yea, what he said. . . Mechanical compression is the number that everyone throws around because a) it's the number that's stamped on the box the piston comes in and b) it's the only number anyone knows. Corrected compression is much more important. This has to do with the mechanical compression minus what is "lost" by how late the intake valve closes. This is the reason some of the posts above recommend against the high mechanical compression pistons with a short duration cam. There's also static compressions and effective compression which have to do with what the engine is really seeing while it is running normally in day to day use.

Best description I've seen of this is in a book by Bill Rook called How to Build a Harley Torque Monster.