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Thread: M70 Rebuild Thread.

  1. #251
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    Quote Originally Posted by dragon850 View Post
    Well well well, 5k of boosted miles under my belt....(11 PSI 500WHP)
    0 oil consumption check, smooth as silk idle check, half a block burn out check, blowing away C7 corvette at 160MPH on the freeway check....
    Sounds like certain somebody has to finally admit calico coating rod bearings was not such a bad idea after all
    That's amazing, Ed! I never had the nerve to go past 120mph fearing a night in the slammer if caught and car confiscated. That's amazing HP achieved.

  2. #252
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    Quote Originally Posted by ChrisFuture8 View Post
    That's amazing, Ed! I never had the nerve to go past 120mph fearing a night in the slammer if caught and car confiscated. That's amazing HP achieved.
    Night in a slammer not too bad, car confiscated ...bad times will reduce speed to 140mph... will that help?

  3. #253
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    Quote Originally Posted by dragon850 View Post
    ...will reduce speed to 140mph... will that help?
    hahaha. Good one.

  4. #254
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    Quote Originally Posted by dragon850 View Post
    Night in a slammer not too bad, car confiscated ...bad times will reduce speed to 140mph... will that help?
    Anything over 100mph will get you a reckless diving charge. Aside from your insurance raping you for years (2 points), you could experience a more intimate version while in jail (5-90 days) and likely end up paying $1200+ in fines. Oh wait, you were racing? Yeah, you're already in jail and your license is gone... and the fine and peanalties for that? You dont want to know...

    Good job on the bearings. There, happy?

  5. #255
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    Quote Originally Posted by cartoonz View Post
    Anything over 100mph will get you a reckless diving charge. Aside from your insurance raping you for years (2 points), you could experience a more intimate version while in jail (5-90 days) and likely end up paying $1200+ in fines. Oh wait, you were racing? Yeah, you're already in jail and your license is gone... and the fine and peanalties for that? You dont want to know...

    Good job on the bearings. There, happy?
    Point taken on going fast
    But yes very happy about the bearings lol

  6. #256
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    Quote Originally Posted by dragon850 View Post
    Point taken on going fast

    A few years ago, even Al Gore's son got the book thrown at him when he was arrested for speeding in OC. Apparently, his Prius was clocked in excess of 100mph!
    1993 850Ci.....18 years & 165,000 miles and counting!

  7. #257
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    Quote Originally Posted by TedBobo View Post
    A few years ago, even Al Gore's son got the book thrown at him when he was arrested for speeding in OC. Apparently, his Prius was clocked in excess of 100mph!
    When would you ever find the open road where you guys live? I was clocked at 127 mph in OH, and the State Trooper let me go. Middle of nowhere, only him and I on the road, all paperwork in order. He asked and I quote " What in the hell do you think you were doing?", and I replied that I was making sure that the car had no high speed vibrations after I just replaced the differential and rear suspension parts. After he ran me through the system, he asked about the car, he knew of them, but had never seen one in person. I would rather be lucky than good, any day.
    Desecrator of all things Sacred

  8. #258
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    Quote Originally Posted by 72tpik5 View Post
    When would you ever find the open road where you guys live? I was clocked at 127 mph in OH, and the State Trooper let me go. Middle of nowhere, only him and I on the road, all paperwork in order. He asked and I quote " What in the hell do you think you were doing?", and I replied that I was making sure that the car had no high speed vibrations after I just replaced the differential and rear suspension parts. After he ran me through the system, he asked about the car, he knew of them, but had never seen one in person. I would rather be lucky than good, any day.
    Great story.

    Between the hours of 1am and 4am our freeways are wide open! That's also when all the high-speed accidents happen too.
    1993 850Ci.....18 years & 165,000 miles and counting!

  9. #259
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    Hey @dragon850, how is your car running 4 years later? Still happy with the decision you made on the rod bearings? I'm freshening an M70 for my e32 (thread: https://www.bimmerforums.com/forum/s...ual-Conversion) and just bumped into the rod bearing problem you encountered. As you well know, the Kolbenshmidt bearings I sourced from ECS are wider and overhang the rods / caps by several thousandths. I've considered 4 possible options:

    1. Run 'em as is. ECS says they'll work and if I install them on both rods that share a journal, they do bolt up and rotate freely.

    2. Shave off 1mm of material. I could do this pretty precisely on my mill, but I worry this could adversely affect the metallurgy unless done very slowly with plenty of irrigation.

    3. Run what I brung. The block I'm rebuilding has 154K miles on it. The lower rod bearings look great, but the uppers show some signs of wear. This won't be FI, so lower stress, but doesn't feel "right" to do it this way while I have everything apart.

    4. Have them coated like you did. Have you perhaps had an opportunity to inspect them since?

    There is no option #5, buy close to $1K worth of BMW bearings. It's not worth that much to me. I'm leaning toward option #2, but would love your feedback. Thanks!

  10. #260
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    Don't listen to ecs. These will not work.
    I am very happy with my decision to get the bearing coated. Did not inspect them because the engine is running awesome even under 11psi of boost!

    Sent from my SM-G892U using Tapatalk

  11. #261
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    I'm going to try trimming the Kolbenshmidts I think. I purchased them a few months ago, and they're no longer returnable unfortunately. Length, thickness and radius are right, it's just the width. I rigged up a jig to hold them securely without scoring the surfaces and should be able to very precisely take a couple of mm off. Worst case, I wreck them in the process and send my existing bearings out to Calico. Glad to hear yours is still running strong!

  12. #262
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    Quote Originally Posted by sutekh View Post
    I'm going to try trimming the Kolbenshmidts I think. I purchased them a few months ago, and they're no longer returnable unfortunately. Length, thickness and radius are right, it's just the width. I rigged up a jig to hold them securely without scoring the surfaces and should be able to very precisely take a couple of mm off. Worst case, I wreck them in the process and send my existing bearings out to Calico. Glad to hear yours is still running strong!
    Hmm, maybe a good machine shop would be able to do a very precise cut.

    Sent from my SM-G892U using Tapatalk

  13. #263
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    using a stone might be a better idea??
    '91 Dinan 860 Stage III (new 6L engine)
    '91 Dinan 850 TT stage III (brand new engine) 21st Century Tech meets 18th Century Dinan...
    '91 850i 6sp (mint) (sold)
    '90 Dinan 750iL TT stage III (Guido - The Beast)
    '94 850 CSi The Detroit Auto Show car (restored to factory perfect) (sold)
    '96 850Ci, The George Carlin car
    ''73 3.0 csi, '08 535i, '03 X5 4.6is
    ...and a few other non BMW cars

  14. #264
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    Quote Originally Posted by cartoonz View Post
    using a stone might be a better idea??
    I worry a stone at anything more than a snail's pace will cause the bearing to heat up and harden. My current thinking is to load each shell into a holding jig and mill them down using several passes and plenty of coolant.

  15. #265
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    are they uniformly too wide, or just one side? That makes it twice as tricky...

  16. #266
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    Quote Originally Posted by cartoonz View Post
    are they uniformly too wide, or just one side? That makes it twice as tricky...
    Just one side thankfully

  17. #267
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    was just reading over your other thread... when you had the machine shop do the heads, did you install the larger exhaust valves? The early M70's (what you have) had smaller valves... Won't make a huge difference if you're keeping most everything stock, but if you are trying to get power out of the engine it helps.

    These rod bearings... they are the ones from the earlier 6 cylinder engines, yes?
    '91 Dinan 860 Stage III (new 6L engine)
    '91 Dinan 850 TT stage III (brand new engine) 21st Century Tech meets 18th Century Dinan...
    '91 850i 6sp (mint) (sold)
    '90 Dinan 750iL TT stage III (Guido - The Beast)
    '94 850 CSi The Detroit Auto Show car (restored to factory perfect) (sold)
    '96 850Ci, The George Carlin car
    ''73 3.0 csi, '08 535i, '03 X5 4.6is
    ...and a few other non BMW cars

  18. #268
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    Quote Originally Posted by cartoonz View Post
    was just reading over your other thread... when you had the machine shop do the heads, did you install the larger exhaust valves? The early M70's (what you have) had smaller valves... Won't make a huge difference if you're keeping most everything stock, but if you are trying to get power out of the engine it helps.

    These rod bearings... they are the ones from the earlier 6 cylinder engines, yes?
    Heads were rebuilt using stock components. I probably should have pursued things like using an M73 block, bigger valves, etc., but my focus has been on staying simple, reliable, and budget conscious.

    The rod bearings I purchased (11241284849) are for the M20 / M50 that several retailers cite as compatible (incorrectly due to width) with the M70 / M73.

  19. #269
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    Quote Originally Posted by TedBobo View Post
    Great story.

    Between the hours of 1am and 4am our freeways are wide open! That's also when all the high-speed accidents happen too.
    1* <--- That reads. One Ass to risk. If there is anyone else out there ( a citizen) slow down homie. Otherwise its your highway. The Palmdale 500 has burried a few into the hillside, here above Tujunga. Darwin awards each and every one.
    One guy recently went F15 straight into the air and a hillside BROKE his fall. 2019 Darwin awarded.
    Last edited by CD05001CIA; 01-12-2020 at 10:30 AM.

  20. #270
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    Well, the bearing milling was a fool's errand. Very tough to hold them securely enough without scoring the finish or deforming them. Given time and patience, I'm sure a suitable holder could be derived, but I'm not anxious to make that my life's work. If you'll forgive the trespass, I'm continuing my hijack of this thread because the e32 board is pretty sleepy! At this point, I'm considering the following:

    IMG_20200119_115519.jpg


    1. Have the 154k mile bearings from the motor I'm building that are broken in to this crank calico-coated, even though they're more worn?
    2. Have the less worn but certainly not perfect bearings from the car's original 84k mile motor calico-coated, even though they're not native to and broken in on this motor?


    The mains aren't pictured, but tell a similar tale. Right now I'm leaning toward the lower mileage option, as they've visibly worn through less of the bearing surfaces' coatings.

    P.S, here are the two offenders that led to this whole mess. Glad I didn't give in to my initial temptation to re-surface that piston and send it. It definitely has a hole all the way through it!

    IMG_20200119_115245.jpgIMG_20200119_115228.jpg
    Last edited by sutekh; 01-19-2020 at 02:52 PM.

  21. #271
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    Go with #2. After all this time I have nothing but great results with calico coating.
    Damn that piston! Remind me what happened to it?
    No problem about hijacking the thread, it should stay alive..
    What piston rings did you use, since bmw ones are NLA...?

  22. #272
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    Quote Originally Posted by dragon850 View Post
    Go with #2. After all this time I have nothing but great results with calico coating.
    Damn that piston! Remind me what happened to it?
    No problem about hijacking the thread, it should stay alive..
    What piston rings did you use, since bmw ones are NLA...?

    Thanks for the continued insight! Cylinder 11 dropped a valve, which slammed around in the bore and eventually ended up sideways. In the process, it shattered the valve seat, ruptured a cooling channel in the head, put that hole in the piston, and fired enough metal debris up into the intake to score all of the cylinders in the left bank

    Piston rings are the one corner I'm cutting since they're NLA. The Alusil bores on this block all look great, and it had very good compression and leakdown numbers before I tore it down. I'm going to leave them right where they are.

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