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  • #31
    Originally posted by janz99
    At least this is my theory anyways, because everyone told me no matter how you set up the mechanical timing, there is no way the valves can hit the pistons, but i some how managed to do so! I had the heads decked, but hte shop only took off .002", not enough for the pistons to contact the valves... seat height and everything else remained the same.

    Ryan

    Non-interference means your valves will not hit your pistons ever(with OEM specs). The valves dont go to a position where they cant get hit. If that was the case if your timing belt snapped at 6500 RPMs I would think you would hit a couple valves in that 1/2 second or so before you valves get into a "safe position." Right? Seems like something else is off. I've slipped a timing belt enough that the engine wouldnt run at a pretty high RPM and broken a belt(not so high RPM) and neither time was any damage done(internally stock DE).
    Adam Kirkpatrick
    1994 Ford Probe GT-T - Built for me, by me, 265whp
    2010 Ford Fusion SEL - Wife's daily driver . . . . . . . . . . . . . 1997 Ford Explorer XLT 4x4 - Daily driver
    1997 Ford F-150 XLT 4x2 - Work truck, wrapped, on 20's . . . 2001 Ford Focus SE Wagon - Work car

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    • #32
      Well im not sure what to tell you guys about these pistons then, because when the timing is setup properly there is a mile of room! but when its not, well here, some pics of the spots where my pistons hit the valves.

      http://www.tylerman.net/images/Ryans-Pics/IMG_3461.jpg

      I have had no problems with the new engine since i had the heads rebuilt and the timing setup properly.

      Ryan

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      • #33
        And you use entierly OEM pistons, valves and cam shafts?
        MazdaSPEED6

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        • #34
          No, we are using the czt kit, wiesco pistons, scat rods, and kl-03 cams.

          We are also using lower compresion pistons, which should also allow for more clearance as well.

          Ryan

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          • #35
            Originally posted by janz99
            No, we are using the czt kit, wiesco pistons, scat rods, and kl-03 cams.

            We are also using lower compresion pistons, which should also allow for more clearance as well.

            Ryan

            Is there a way to confirm they are low compression? Can you just measure the piston height compared to stock? Obviously from that picture the valves hit, no one can deny that. Seems to me like the pistons are too tall or the rods are too long creating and engine that is no longer non-interference.
            Adam Kirkpatrick
            1994 Ford Probe GT-T - Built for me, by me, 265whp
            2010 Ford Fusion SEL - Wife's daily driver . . . . . . . . . . . . . 1997 Ford Explorer XLT 4x4 - Daily driver
            1997 Ford F-150 XLT 4x2 - Work truck, wrapped, on 20's . . . 2001 Ford Focus SE Wagon - Work car

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            • #36
              Since your valves are obviously contacting the pistons this can only mean a couple of things.
              1. They decked the engine remove more than .035"
              2. The wrist pin location is to high in the head of the piston
              3. The piston head is to thick
              4. Rod length is incorrect (to long)
              Rick_96PGT #62
              "I never apologize.
              I'm sorry, but that's just the way I am."
              - Homer J. Simpson

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              • #37
                I think the problem with alot of custom pistons is that to accomodate higher cam lifts they deepen the valve pockets and then they have to raise the crowns to compensate for a given compression...

                From what it looks like it only just hit the outer edge, it didn't barrel into the center of the piston or the relief like it would if there was really something wrong with the piston..

                It looks more like the entry angle of the valve into the relief wasn't cut at the exact angle, since the relief IS obviously there, its just not quite clearanced enough.

                I mean you can see that they have a groove that occurs right where you have the hit, looks like maybe wiseco didn't take out enough material to get it to clearance under every condition.
                Last edited by cyborgzero; April 5, 2006, 07:53 PM.

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                • #38
                  Well i checked the compression on the engine after it was broken in, and i am getting 160psi on all the cylinders, which is pretty much exactly what i should be getting. The pistons/valves arnt hitting anymore, like i said before this was only when i hat the mechinical timing WAY OUT! Now that the heads are rebuilt and the timing is correct it has a TON of clearance!

                  Ryan

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                  • #39
                    well i'll add my 2cp worth..

                    About 6 months ago, Brian from Wiseco and I were on the phone and he actually changed the specs in the computer and piston model with me on the phone.. He relocated the valve pocket centers and made them a wee bit larger.. I shipped him my damaged postions with the valve centers templated on the deck so they could see where the valves really are and they made thier changes according to this.

                    Anyone who ordered Wiseco pistons in the past 6 months or so should have the revised piston design that Brian and I worked up. Im running these pistons now in my car and there is plently of clearance and is still a true no contact motor.



                    Jason
                    1996 Turbocharged Probe GT SOLD.
                    T04B, Megasquirt 2
                    CLICK HERE FOR PICTURES
                    H-Trim TO4B, 262whp / 272wtq

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                    • #40
                      ^ Actually that's VERY reassuring, since I bought my Wiseco's a couple months ago. Thanks!
                      95 PGT MTX - Probezilla - Supercharged 'n Squirted ZE @ 8 psi
                      93 FD - LSx 7.0L - 11.6@128.5 (w/ old rotary setup)
                      89 DTM PGT - 49K ORIGINAL miles! - MINT! - Sold
                      04 Subaru WRX STi - Perrin FMIC, Greddy 3.5" catback, K&N intake - 308AWHP/318AWTQ - Mustang Dyno
                      Probezilla & The FD 540 RWHP/415 RWTQ @ 24.5 psi (past rotary setup)

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