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  1. #21
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    holy cow, Miura engine? Wow. Even the engines out of that era Italian sports cars were beautiful. I don't think a twin cam V12 from a $350-800,000 car would be one I'd want to learn on. I'd start with Briggs&Stratton, then a nice single cylinder motorbike and then work up to something out of a Ford Focus. And then I'd save up a few 10s of mortgage payments and pay a specialist not to screw things up.

    wow, though. I'd love to see pictures, I still think those Miuras were one of the most beautiful cars ever made.

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    Quote Originally Posted by dantm View Post
    This is a Lamborghini 4.0 engine as is on a Miura, Countach cca. 1965 - 1979 vintage.


    Will 1 mil of clearance on each side of the piston (piston to wall) be enough?
    I don't know the spec for the Lambo, but I suspect that's too tight. That would heat up and seize in my unknowledgeable opinion from out my ass.

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    Quote Originally Posted by kustomizingkid View Post
    That's a motor you take to place with a reputation for performing that type of work flawlessly... thats also not a job you save money on lol. I would get a recommendation from Ross on where to take that motor and write the checque.
    Seconded. PM to "AlfaGTA"

  4. #24
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    Quote Originally Posted by dantm View Post
    I'm trying to rebuild an engine for a car that I am restoring. Based on the leakdown testing, compression testing, etc. I think we need to look at boring the block, oversize pistons + rings, cleaning + polishing crank, new bearings, etc.

    I'd like to educate myself such that the local shops doing the work won't be able to push the work beyond what is necessary.

    As such can anybody here recommend some online forums where I can post questions, get feedback, etc.?

    Thank you!
    I'm not sure what your roadmap is exactly,

    but the German Subaru guy has a number of vids devoted to a special 2000HP lambo engine ,

    but you can watch some vids of his that were dubbed over in English , as well as the German vids,

    There you get an idea of what's involved and some of the tolerances involved / issues ,

    Your block is more historic than these vids. [i.e. don't blow your engine up.].



    ^^^ In English dubbed,



    ^^^ In German "LP-X Projekt - Höchste Präzision für MONSTER Lambo ! | Subi-Performance " ~ LP-X project - high precision for MONSTER lambo .

    Other vids on the Lambo engine block - (more recently Subi-performance bought a new honing machine / pretty cool.)

    You can post questions and sometimes get answers.

    How to build a 2000HP Lamborghini Engine l Part 1 l Subi-Performance - YouTube

    Part one ^^^ but in English narrated by "Subi-Performance" . Some interesting set ups.

    etc. The Subaru engine builds are super interesting + final tolerances and work.

  5. #25
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    At the risk of looking like a buzz kill, I watched a couple of his Subaru videos and am not impressed at all. He line bores them with a hand held, albeit piloted, adjustable reamer. He installs sleeves with an entire tube of sealer on the sleeves and in the bores, with no interference fit in the block! To see it done properly, this other Youtube blowhard has it down.
    Subaru EJ line boring in RMC V40 CNC mill - YouTube
    Installing sleeves in Crest Subaru billet block with liquid nitrogen - YouTube

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  7. #26
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    There is a real good engine rebuild shop, Dark Horse Inc in Madison, NJ, only a couple of hours from Mass. He specializes in Ferrari engines, they are shipped in from all over the world for him to do.

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    Second the recommendation for Speedtalk.com. Lots of knowledgeable folks there.

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    Wow thank you all for the replies, I was not expecting such a big response.

    The car is actually a Countach not a Miura, so it's not a $2M vehicle since some asked.

    I have a mechanic who is working on the vehicle restoration and repair and he's very meticulous to detail but is not an engine rebuilder. Goal would be to supply the minimal changes needed based on the original finding of poor leakdown in at least 2 cylinders.

    As such some thoughts I had:

    (1) re-bore and hone cylinders to the next oversize (82.2 mm vs 82 mm current). The liners protrude above the deck by approx. 0.1 mm based on the engine repair manual and I'm assuming it'd be a best idea to do it in place with a torque plate and the crank caps installed and everything tightened to the right torque in order to have the block in the final stress/tension?

    (2) custom made pistons by JE/Ross/RS (?) based on sending out an old piston. How do I capture the wrist pin size against the spec and the connecting rod?

    (3) (ideally) polish the crank - I measured the journals and mains and they are quite close/tight together (as an example for journals): 43.54 - 43.56 mm for the 6 journals, against a spec of 43.604 - 43.594 nominal. The next undersize (?) range is 43.340 - 43.096, so does this absolutely mandate to grind down the crank to the next size and use the +0.010" oversize bearings?

    I'm not planning to do the work myself but the shops that I found were either high end shops with an entry point of 200 hrs labor @ 150 per hr for exotic car restoration, or other shops that wanted an open checkbook for learning on this engine. So at least for now I'm trying to educate myself and learn through this process - first rule at least for me is to do the least amount of changes/modifications if possible.

    Thanks to all once again!

  11. #29
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    Yes, caps torqued, head gasket in place and a deck plate. That minimal an oversize on the bore should be honed, not bored and honed. Reason being, typically one leaves .004" of material to hone out after the initial bore. Going .2mm (.008") over, means you need to bore only .004" out of the liners, or .002" depth of cut. Any machinist knows that is not advisable for at least 4 reasons I could list. A modern diamond hone will make quick work of that .008" increase.
    You really should start speaking in inches, not millimeters, this is not Europe. Yes, we can convert but if you have the machine work done, it'll be measured in inches. Your crank specs show a full .002" of wear, which is a mile in crank land. If you've measured correctly, you do need to go undersize. But you should have a reputable crank shop measure it, mag it, and check for straight before going further on it. Finding a good crank grinder will be a challenge. I've ground cranks for 35 years, seen horrible examples of crank work over the years and it is getting no better. It's a nasty awful operation, which is why I stopped doing them a couple of years ago and I am much happier for it.
    JE and the like will make pistons as per a sample, pin and all. Expect a long wait and a large price.

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  13. #30
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    Thanks for the info...would the bore/hone strategy change if we went .010" over rather than .008"?

    The pin itself has a wear (0.7472" vs 0.7480 - 0.7479" spec) so I assume the nominal pin size would be provided to JE so that they are matched to the connector rod?

    How do I ensure clearances between the connector rod and the pin where the wrist pin bushing is?

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    cool car, I remember hearing one of those many years ago, quite unforgettable. Prices are all over the place, from $50k up to $500k depending on year and provenance.

    I'm not familiar with how engine rebuilders work, but my first step would be to find a reputable rebuilder who would take on your project and then get a quote (or better, quotes) for the bore honing, replacement pistons and the crank grinding/ new journals. If you've gotten that far into it you're clearly able to put it back together again. What's the rest of the engine look like, especially the valve train?

  15. #32
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    I've no experience with exotic engines, but I'm currently rebuilding an old small block Chevy and an old 235 inline 6 at home. Both of my builds are a mixture of rebuilding for wear AND making custom "period" upgrades, so while I could have just swapped engines or farmed out the rebuilds, it would be hard to get the desired custom aspects, so I think you're on the right track wanting to understand the process, but I think how you use that information has a big bearing on your success rate. I have a local engine shop that has a good reputation and is easy to work with, so my process has been to analyze the individual components and then farm out the individual tasks to that shop, which they've done happily. I have made a couple mistakes however that could have been missed if I had dialed back my own involvement.

    Jobs like restoring vintage cars take in so many trades and it's very much a DIY experience, but it helps to take a step back sometimes and see yourself as more of a contractor than the sole laborer. Body work is often forgiving enough that you can fix your mistakes and get decent results on your first car, but rebuilding engines is very much a by-the-numbers game where the knowing the numbers is 90% of the battle. Being able to offload some of that responsibility to someone more experienced really helps. In my case, the small block build has been mostly paint-by-numbers with a couple cases of trying to figure out how different aftermarket parts will work together. The Inline 6 on the other hand I'd had to figure a lot out on my own as they're less common in hotrod'd form as compared to a stock build, which has lead to more mistakes on my part.

    The other side of this is that when dealing with highly skilled trades, IMO the metric for determining the competency of a potential shop or individual should not be to learn the fine details of what they do and then test them with your business. Learn about their success's from past clients and jobs and leave the "how" to them. You're not paying for the mystery of their fine craft, you're paying for their ability to turn out correct work. The only thing you have to figure out is how "custom" your job is and therefore how much you can purchase and how much you need to do yourself.

    If it were me, I'd see an exotic engine as a rare, but still "stock" job. So I wouldn't send it to any old shop, but I also wouldn't want to get in the way of having it done right either.

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    like the old saying goes SPEED COST MONEY ! HOW FAST DO YOU WANT TO GO ? two things this is a for real post of hey i am a newbie and i want to be a brain surgeon right out of the gate or its a hey look at me pounding his chest thing ! wow

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    The heads have been worked on by a local machine shop that specializes in such and they *should* be good to go - I understand that may have its own set of challenges once we get into it. So far I've translated the engine manual from Italian only up to the block completion.

    One more question, in the engine manual there are two numbers listed for the pin, and they are given in a 'color' table, for white and black. Does anybody know what this refers to (the direct translation is as in these pictures)

    pin.jpgpiston.jpg

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    Quote Originally Posted by M.B. Naegle View Post
    If it were me, I'd see an exotic engine as a rare, but still "stock" job. So I wouldn't send it to any old shop, but I also wouldn't want to get in the way of having it done right either.
    Yes I fully agree, these engines were probably late 1950s to early 1960s designs so I highly doubt that they were anything special at that time. If one was to rebuild a late model Porsche/Ferrari/Lamborghini or any other high performance car it'd be conceivable that the tolerances could be much tighter and require more specialized work.

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    Quote Originally Posted by 1yesca View Post
    like the old saying goes SPEED COST MONEY ! HOW FAST DO YOU WANT TO GO ? two things this is a for real post of hey i am a newbie and i want to be a brain surgeon right out of the gate or its a hey look at me pounding his chest thing ! wow
    I'm not trying to become a machinist by any means. I want to do the minimum amount of work (invasiveness, cost) to get this engine back up and running. As I'm investigating the process/journey of going through the rebuild I want to make sure I have an impartial group of opinions who have no bias on the job itself.

    Case in point, I talked to a local shop, nice clean outfit, does custom work and old rebuilds. Very meticulous and attention to detail is high. Has not done this exact engine before. We chatted initially about boring/honing block, buying/making torque plate, and installing JE pistons to end up with a short block. Got an estimate of $2.5K just for this (reasonable). I asked for a written estimate and got back a $6K job that included washing the parts, checking the crank (not sure if even polishing was in there), weighing (balance check) of the parts, I assume rods/pistons, and resizing the rod big end size. Subsequently was warned by same shop that this can turn into a $50K job if we have to get into *everything* (I think rebuilding heads were in scope for this price).

    With this large variation I'd really like to know what I'm getting into and how to go step by step through this process.

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    Quote Originally Posted by dantm View Post
    Yes I fully agree, these engines were probably late 1950s to early 1960s designs so I highly doubt that they were anything special at that time. If one was to rebuild a late model Porsche/Ferrari/Lamborghini or any other high performance car it'd be conceivable that the tolerances could be much tighter and require more specialized work.
    Nothing special lol... ya dude take it to the local circle track and have it dun up.

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    Just in labor adds up, let alone parts costs. an hr here, an hr there and so on adds up fast. expect 10-20 grand easily.

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    Sure, I'm not looking to get it done for free...10K labor + parts is ok, 50K is difficult to get into immediately :-)

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    Quote Originally Posted by dantm View Post
    Sure, I'm not looking to get it done for free...10K labor + parts is ok, 50K is difficult to get into immediately :-)
    I definitely recommend going into whatever shop you chose and educate them on how to rebuild your motor. Machinists love that shit. *heavy sarcasm*

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