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Cam Choice

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  • tussuck
    tussuck
    2 years ago
    Just keep in mind that some cams are good in baggers and others are good in lighter bikes.  I have always run an EV3 (or EV35 when on the turbo) and found them a good cam.  Solid performance from about 2800 rpm upwards to my normal rev lint of 5500 - but then can do 6000 no problem.
  • evo94
    evo94
    2 years ago
    evl 3010 ...quieter
  • fatbat
    fatbat
    2 years ago
    I wouldn’t split hairs over either and you’ll be happy one way or the other 
  • tussuck
    tussuck
    2 years ago
    Yep, Woods #6 or EV27 will keep you happy!
  • tussuck
    tussuck
    2 years ago
    Yep....EV13 has always been the goto choice for baggers!
    I would love to drop in a EV49 one day just for chits and giggles to see how it goes.
  • Hoodeng
    Hoodeng
    2 years ago
    Use the EV13 in an unmodified tourer and it will give better overall performance, the inlet close is similar to stock so will give similar cranking pressure = early torque. the 13 has more overlap than the stock cam so will have more legs than the stock cam.
    The EV27 has a later closing than the 13 so will make torque a little later, in a lighter bike maybe not that noticeable as the engine spools up quicker, in a heavy bike the spool up is held back by the weight of the bike so is more sensitive to a later closing inlet.

    If you ever have the top end off for a freshen up, check and set the squish to .040" even if you do nothing else, some early evo's had anything up to .070" and more piston to head clearance. This alone will sharpen up a sluggish evo...

    And tune, i have seen engines installed with the stock ignition cinched down to the stock location scratches that the owner put there on disassembly, and have convinced themselves that as it work perfectly there before, why would you shift it???
  • Grease Monkey
    Grease Monkey
    2 years ago
    Think Hoody ment a bagger for the 13, if I was you with the softail it would be the 27 for sure.
  • Hoodeng
    Hoodeng
    2 years ago
    Wombat, what i mean by modified is internals, not bolt on, comp, capacity, etc. Bolt on's like air cleaners, carbs, ignitions, pipes etc help a stock package but have not fundamentally changed the engine core in any way. Case boring stock cases is to be avoided.

    These bolt on's can/will improve performance when the engine is tuned to suit. When internals are changed particularly comp, will broaden the torque curve appreciably over the whole range when matched to an appropriate cam, the bolt on's quoted earlier are also reqd if going down this path.

    The stock CV will support more HP than most would think when jetted to complement the whole package, carb kits as such presume too much about a engines state of tune requirements.

    What i said about squish is actually in the design of the engine by Harley Davidson when it was first drawn up, it is tolerance stack up and construct that made it get where it was. I have never seen an evo engine with the design squish yet, a couple have come close but typically it is always over by a mile.
  • Grease Monkey
    Grease Monkey
    2 years ago
    Take note of what Hoody has said in his posts, free advice from one that knows wtf he is talking about.
  • Hoodeng
    Hoodeng
    2 years ago
    If you are planing to change the internals, comp, head flow etc down the track, you might as well leave it alone for now and wait till you do the whole job in one hit. It is unlikely that a cam you chose now for a stock bolt in application will have any relevance to the direction you see your engine finishing in.
  • tussuck
    tussuck
    2 years ago
    Good call and a good build for a little extra omph.  If you can spring it then its worth shaving a few thou off the heads as well - Evos respond REALLY well to nudges on compression.
  • 408
    408
    2 years ago
    Hoody suggested you could check the squish. That is the first thing you should do before thinking about shaving your heads.
    You can bump compression by reducing your head gasket thickness.
    You can also reduce your base gasket thickness. Stock is 0.020", Cometic make a 0.010"base gasket. I run pigtails with a smear of Yamabond.
    This is all stuff you can do yourself with a bit of reading up. And use the Big Boyz calculator to see where your compression is.
  • 408
    408
    2 years ago
    You looked at the twin cam calculator. There is a compression calculator for Evos.
    Plenty of articles about checking your squish. You need to have a basic understanding about checking your compression before you go any further.
    Checking your squish will give you an idea how to proceed with head gasket and base gasket thicknesses.
    A couple of different manufacturers make pigtails to bridge the oil line gap between the cases and the cylinders to nullify oil weeps at the base gasket.
  • tussuck
    tussuck
    2 years ago
    Checking the squish is removing the heads and putting plasticine on the piston crown and then reassembling with new gaskets etc and then turning over by hand so the valves make impressions in the plasticine.  You then remove the heads and section the plasticine to see how close the valves came to the piston as well as the depth of the flat squish zone.

    The operation of shaving the heads is easy for a good shop to do as they set it up in the milling machine and basically cut 20-50 thou of the head surface.  Might be a couple of hundred bucks - but tbh I have no idea on cost.  Do you stop there and then also do a 5 able valve job as well.  

    I do always reseat the valves and lap them in when removing the heads as its something anyone can DIY. 

    It may be easier to just run thinner head gaskets sometimes.  (make sure to turn the engine over manually before firing up to make sure nothing is binding or touching)


  • 408
    408
    2 years ago
    Quoting tussuck on 15 Aug 2022 12:02 AM

    Checking the squish is removing the heads and putting plasticine on the piston crown and then reassembling with new gaskets etc and then turning over by hand so the valves make impressions in the plasticine.  You then remove the heads and section the plasticine to see how close the valves came to the piston as well as the depth of the flat squish zone.


    The operation of shaving the heads is easy for a good shop to do as they set it up in the milling machine and basically cut 20-50 thou of the head surface.  Might be a couple of hundred bucks - but tbh I have no idea on cost.  Do you stop there and then also do a 5 able valve job as well.  

    I do always reseat the valves and lap them in when removing the heads as its something anyone can DIY. 

    It may be easier to just run thinner head gaskets sometimes.  (make sure to turn the engine over manually before firing up to make sure nothing is binding or touching)



    That is not checking squish, that is checking piston to valve clearance.
    Checking squish does not require having heads in place, just checking the position of the piston at tdc relative to the cylinder.
    The gasket and cylinder stack height is adjusted for the required squish.
  • John.R
    John.R
    2 years ago
    You can't assume anything, all has to be measured.

    Measuring the deck height on my cast pistons was bit annoying.

    Deck height and squish are different though.
  • John.R
    John.R
    2 years ago
    For a drop in cam they won't bother. 

    Think we're gettin lost in the sauce a bit, just throw a cam in it and run it.
  • 408
    408
    2 years ago

    We haven't got on to domed pistons yet....
  • beaglebasher
    beaglebasher
    2 years ago
    I am trying to catch up with this thread.  What  is this "SQUISH" thing?
    Its a term I am not familiar with. I have a fair idea what it is but for the benefit of everybody on the forum " SQUISH "  needs to be explained.  I cant be fucked googling it.

  • WideglidingNZ
    WideglidingNZ
    2 years ago
    Quoting beaglebasher on 15 Aug 2022 09:53 AMedited: 15 Aug 2022 10:01 AM

    I am trying to catch up with this thread.  What  is this "SQUISH" thing?

    Its a term I am not familiar with. I have a fair idea what it is but for the benefit of everybody on the forum " SQUISH "  needs to be explained.  I cant be fucked googling it.

    https://en.wikipedia.org/wiki/Squish_%28piston_engine%29 hopefully this explanation might help
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