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piston clearance and CR

Discussion in 'Engine Building' started by 22crazy, Mar 2, 2004.

  1. 22crazy

    22crazy Senior Member

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    Nov 13, 2002
    Hello, im probably just going to continue from my old post...but my question here will probably be a good tech question. I was just wondering...ive been reading up upon aftermarket camshafts and noticed for high performance ones u need to bump the CR for them to work properly...i think it has something to do with the crank case pressure, but i dont know for sure (little help?). but my real question was if u need higher compression to satisfy the camshafts yet the higher compression u go, the more of a chance u have to smash your piston's into your valves. The reason im saying this was because i wanted to use CTR pistons in a LS with crower 404's or cranes 0016/18...however i have heard many things about piston clearance. CTR pistons in a LS will yeild a CR of 11.5:1...for a real monster N/A, probably 12.5:1 would be desirable...but if theres piston clearance issues at 11.5, how do u overcome to reach 12.5. I know u can clay ur motor to see if theres any contact...but what if there is? what do u do then? how do u take the full advantage of the cams without blowing ur motor. I would really appreaciate if someone could explain this :worthy: . thanks in advance.
  2. pissedoffsol

    pissedoffsol RETIRED

    Likes Received:
    Sep 28, 2002
    Retirement Home
    bigger cam = longer/higher valve opening = needs compression to utilitize said space effectively.

    CTR pistons won't fit LS rods- so keep that in mind.

    aftermarket high-dish pistons have deep valve reliefs for just this purpose.
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