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Valves and pistons hit.

Discussion in 'HYBRID -> ED-EF / DA' started by CrixSi91, Aug 16, 2012.

  1. CrixSi91

    CrixSi91 Junior Member

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    Ok so I'm trying to build a mini me. I have a 91 sedan with the a6 already in it. I researched as much as I could before starting and then some during the build. So this is what I have… A6 block, z6 head, z6 IM, z6 dizzy, z6 head gasket and z6 timing belt. So I went ahead and put everythin together. I set the engine and head to TDC before bolting it together. I used new ARP head studs and all new OEM gaskets. So as of now the block and head are together with the timing belt on. Now when I go to rotate the engine a 1/4 turn counter clock wise before re tighting the adjuster bolt, everything hangs up and stops spinning. I cant turn the crank in the counter clock wise direction. To me it feels as if the valves are hitting the pistons. Now if I put it one tooth out of time in either direction it will turn over fine. Wondering if this happen to anyone else or if anyone knows how to fix the problem? I'm not sure what's going on. I did everything just as everyone has posted but yet I can't the engine over without it feeling like the pistons are hitting the valves. Maybe I'm doin something wrong maybe not. All information will be greatly appreciated thanks in advanced.
     
  2. CrixSi91

    CrixSi91 Junior Member

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    Well didnt have time to mess around with it very much. I needed the car back on the road ASAP. I took a a6 head off an engine a friend of mine had in the garage and just refreshed everything with new gaskets and seals. Maybe one day when I have the time I'll figure out why I was having this problem. This post can be deleted now, thanks.
     
  3. Briansol

    Briansol Admins Admin VIP

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    It may just be high compression making it feel like its hitting. Only way to know for sure is to clay the motor and turn it over and check for imprints.
     
  4. TurboMirage

    TurboMirage YEEAAAHHH VIP

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    i was going to ask if you left the spark plugs out...

    glad you didnt try to force it though. that did me in once, when i was young and dumb.
     
  5. djbacker1

    djbacker1 New Member

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    The a6 pistons are taller than z6 pistons. The z6 pistons are machined to fit the valves. I am building a motor for my sons car replacing the z6 block with a salvaged a6 block. Finding a lot more issues as I get further into it. Timing belt, water pump, tensioner, motor mount, etc...
     
  6. djbacker1

    djbacker1 New Member

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    I shouldnt say the a6 pistons are "taller". Really, they are just not machined as deep as the z6 pistons, making room for the valves of the Vtec head.....
     
  7. CrixSi91

    CrixSi91 Junior Member

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    Thanks for the replies guys. Yeah I had the spark plugs out, so I know it wasn't due to high compression. Ive never clayed an engine before, I'm sure it won't be hard to figure out. Djbaker1 that makes sense. I did notice a big difference in the top of the z6 pistons compared to the a6. Well one day I'll get the chance to try it again and figure it out.
     
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