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327 steel crank question

Discussion in 'The Hokey Ass Message Board' started by vrod64, Aug 25, 2011.

  1. Building an early 60's 327 with original steel crank. Any thoughts -comments on turning it .030 ? One journal needs turned, so planning on turning the entire crank.

    Will be a 10:3 motor with Scat rod and long skirt TRW pistins. No nitrous and will rarely see 6500 rpm.

    Any experience ....... with a .030 steel crank.


  2. Your crank is that bad? I have seen them turned a ton with good results, I seldom use a crank that is more than .010 under myself.

    Its a bad rod or main journal? If the rest of the crank were in tolerance I would just turn the rod or main journals depending on which is the offending journal.

    One other thought is that if it is just one journal bad it is a steel crank why not get it welded up and turned to match the others. Just a thought.
  3. Thanks...Crank is good. Thought about welding it up, but want to keep the excess heat off of it. Other journals are .020.

    Thanks Bean
  4. Take it to a shop that can weld it if you do. A good shop will put it in a lath that has a welder attached to it especially for welding up cranks they use core wire but I don't recall the designation, I'm pretty sure it is low-hy.

    The heat won't hurt it they have been welding up steel cranks forever. That used to be how they changed the stroke before companies like scat started makeing one of everything for one of every application.

    You will probably be alright with .030. At least your bearing speeds/loads will be lower. Its not like you're going to be running it on pop.:D

  5. BootleggerJim
    Joined: Dec 14, 2007
    Posts: 202

    from SC

    No problem turning a steel 327 crank .030, hell you can go alot more and use lighter rods....Jeze men....
  6. I guess I just can't see turning an entire crank for one offending journal. Every time you turn it is just one rebuild closer to throwing it away.

    Cost to weld and turn one journal will be close to the same as turning the entire crank or maybe a little less if you get it done in the right place.
  7. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    from MI

    Having the fillets done correctly effects durability a lot more than whether or not it's .030 under.
  8. 26 roadster
    Joined: Apr 21, 2008
    Posts: 2,015

    26 roadster

    gentleman Ed Hail, El Cajon Raceway, turn all his race car engines 30-30 way back in the 70-80's
    if your scared I would pay the freight on that junk crank
  9. fossilfish
    Joined: Dec 16, 2010
    Posts: 320

    from Texas

    .030 is no problem. That is just .015 on each side. Put a good fillet on it too. If you ever look at a welded crank up close on a magnuflux machine you will never weld one.
  10. No one is afraid to turn one .030. The man asked for advice and I gave him good advice along with options.

    We used to punch 283 .125 also I am not afraid to punch one that far today any more than I am afraid to punch a 350 .060 but every time to remove metal you either make it the last time the engine is worked or come one step closer to it being the last trip for the part in question. As the parts we want become more and more scarce that becomes more important to bear in mind.

    I am a mechanic not a parts replacer I don't just jump in and do something that doesn't need to be done. It is different if I am building a race engine, I am not beyond hogging out the ports or taking it to the limit to shave .0001 of my time. I don't get the impression that we are talking race engine here.

    You are right about radiused journals by the way. It doesn't get done enough as far as I am concerned. I wouldn't turn one just to radius it unless like I mentioned before it was a race engine.

    We ran welded cranks in the Pro Stocker all the time in the early '70s never busted a crank. My first stroker motor was a stroked 312 in '69 welded crank, ran that car 'til '71 busted a cam, several rockers and a rod once never busted a crank.

    Cranks have been being welded since the very beginning of trying to make one bigger. Very common practice for a very long time.

    I suppose if any one of us ever had a chassis exrayed we would never get back into a car.
    Last edited: Aug 25, 2011
  11. Danny G
    Joined: Aug 1, 2006
    Posts: 399

    Danny G

    Call Flanakin @713-683-1023, he can weld it but I wouldnt be scared of it.
  12. Yeah, you can safely turn this steel crank 0.0030 but it's the last time you'll turn it without welding it up again, like Benno said. Good news is there are still a pretty good supply of big journal 327 steel cranks available. Last time I needed a 327 crank my machinist raised his eyebrows when I asked him if he had one in the shop...
    "Yeah" he said. "Everybody that comes to me wants to use a 350 or a 400 crank and I get all their old 327 many do you need?" He never sells them because nobody wants them. He laid one on me for free as long as I paid for the machining and balancing. He was glad to get rid of it.
    Go 30 and don't worry about it.
  13. redlinetoys
    Joined: May 18, 2004
    Posts: 4,301

    from Midwest

    Interesting info.

    I just picked up a fresh steel crank 327 engine complete with new Keith Black pistons and a ton of other good parts including fresh heads (all of it for almost scrap price).

    The guy had the engine listed for months with no one taking a look. I agree, all the younger modern crowd wants either cubic inches or even an LS1.

    Myself... I was thrilled to pick up this sweet little vintage engine!
  14. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    from MI

    Grinding fillets and side clearance uses up the stone faster. Some grind cranks undersize and don't touch the radius at all, leaving a step!:eek: That's what you definitely don't want. Experience shows that to get good durability the fillet radius doesn't need to be as big some believe, but it does need to be done right.

  15. Not my cranks they don't. I always look at what comes out of a shop if I am not doing my own machine work. I normally try to work a deal with the shop if I don't know the machinist real well, pay full price and do it myself. believe it or not that has worked for me on more than one occaision.

    These days I just stick to shops where I know and trust the work. There are enough other things in the world to make me achy without going looking for some.
  16. Beaner: Great help. Bearing speed comment was good.
    Fossil Fish: magnaflux comment great.
    Danny G: Trust you like the Pope cause I have seen your Stude run @ Temple!

    Thanks HAMBers. My machinest (Westside) is pretty good. Keeping the crank Journals @ .020 and rod journals @ .030. Motor mock up with weber 48 IDA's. Just needed some assurance .

  17. vrod, crank grinders are a dying breed. With the advent of NEW cranks for $200, they are becoming even more scarce. All good advice, dont be afraid of a welded crank, anymore than a .030" undersize crank. Make real sure that they leave you a far amount of radius in the jounals, as well as a nice chamfer on the oil holes when they are done. MOST IMPORTANTLY, before you final assembly the bottom end, clean the crank inside and out, SEVERAL TIMES!! Make sure those oil passages are crystal clear, OK. Have it magnafluxed, and ask him to check it for straightness BEFORE he grinds it. I'm giving you good advice here. The key here is the machinist, like most aspects of engine building, it's all in the hands of the knowledge and experience of the man turning the levers, handles, and knobs. Love that intake set up with the quad Webers {or Delortos}?, COOL, TR :D
  18. vrod, if I may, when you final assemble the bottom end, pay close attention to connecting rod side clearance, and the crankshaft end float or end play. TR
  19. Vrod
    Am I seeing magnesium halibrands behind that slick 327?

    You will do fine.

    Now if I can just get Rocky to get me one of those large journal 327 cranks I will be one 400 block away from the 350 that GM should have built. :D
  20. Truckedup
    Joined: Jul 25, 2006
    Posts: 4,130


    I've been told by engine builders a steel crank turned more than .010 shouldn't be used in a performance engine.By performance I mean high RPM and lots of HP.The cranks are hardened by the factory for durability. Often this treatment doesn't penetrate more than .020.A good crank grinder will check the crank for hardness before machining.
    I'm not saying the crank will fail if turned,not saying I'm an expert,just saying what some builders say..............
  21. bob308
    Joined: Nov 27, 2009
    Posts: 220


    i ran a welded 327 crank in the dirt car. ran fine no problems. even built a welded strocker no problems.

    not all steel cranks were tufftrided from the factory. infact the only one i have seen was in a 366 big block.
  22. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    from MI

    Ordinary production automotive cranks are not hardened. A few high performance factory muscle car cranks were, but it wasn't common. Tuftriding and nitriding aren't the same thing. Tuftriding only produces a thin skin, so yes, grinding one of those will remove most or all the treatment. The hardness on conventionally heat treated and nitrided cranks is deeper. Although it can vary with the crank and the process used, the hardness on heat treated and nitrided cranks is usually still sufficient at the dimensions one would normally want to grind the crank to. Industrial and heavy truck engines normally have heat treated cranks. Those can be reground without giving up much. Piston airplane engines usually have nitrided cranks. Hardness is one of the things checked when one of those cranks is ground. But as I already said, normally it's not a problem.
  23. My crank is a SMALL JOURNAL 327 steel crank, so it's almost 50 years old if it matters. Not sure how these were "treated' back then.

    Thanks for all the help. Pretty heavy topic.
  24. Truckedup
    Joined: Jul 25, 2006
    Posts: 4,130


    I know that cast cranks are not heat treated. But from what I understand GM routinely hardened forged crankshaft by induction. For sure the old 235 Chevy had heat treated cranks.
    Again,I am told this by crankshaft machinists.............And I know a lot of racers have used welded cranks with no problems.
  25. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    from MI

    Induction is a method of heat treating. What that means on a crankshaft is that rather than heating and hardening the entire crank, only the journals are heated and hardened. That method can only be done when the material the crank is made of is heat treatable. As I remember production Chevy steel SB cranks were just mild steel. Better than iron, but not heat treatable, and far from as good as it gets.

    "Cast" is a process, not a material. Both iron and steel can be cast. If you meant cast iron: although things can be done to most(but not all) iron cranks, an induction hardened iron crank would be very brittle.
  26. Here are the facts. Most stock OEM cranks are Induction Hardened. The depth of the process is around .060" to .080" deep. Ideal for stock, non high performance applications. Tuftriding is next, used by the OEM, for H.P. applications, to avoid the spossible stresses imposed by Induction Hardening. This is very shallow, only possible to be around .005" deep. A drawback is possibility for warpage. Nitriding cranks are next, they typically have a depth of .010" to .030" deep. a lower heat process than Tuftriding, and avoids the localized stress zone as in Induction Hardening. A stock OEM Forged crank can be welded and reground with no concern. Tuftrided cranks can also be welded and reground without concern, although the shallow depth of the hardness will be lost. The crank should be hardened again after rework. Nitrided again too can be welded and reground without concern. A .010" cut will cause SOME loss of the Nitriding. A .030" or more grind and all of the Nitriding will be lost. Therefor the crank should be hardened after a repair of this magnatude. There are also special considerations regarding the thrust, but I'm not typing that info at this time. These are the facts by one of the biggest most trusted names in the crankshaft business, racing, OEM and everything in between. TR
  27. More facts, cast iron cranks do NOT need to be hardened. During the machining process, the cast iron crank will become " work hardened ". :D
  28. A .030 under crank is no worse than a std. crank as long as the radius is maintained. The only drawback as mentioned before is it is one step closer to junk. Look real close at the fillit if the radius has already been ground out you might want to get another crank anyway.
  29. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    from MI

    If you are talking about OEM automotive cranks, your facts are faulty. Most old cars had iron cranks, nearly all newer cars have iron cranks, and they are not heat treated in any way. Of the cars that have steel cranks, few are heat treated, Tuftrided, or anything else. When you want to seriously race a newer engine one of the first things needed is a high quality steel replacement for the stock iron(or low grade steel) crank.
  30. snaptwo
    Joined: Apr 25, 2011
    Posts: 696


    We ran a small journal 335 in the old snap too corvette in front of a clutchflite,we launched at 5000 and twisted that sucker to 8500-9000 on the big end. Yeah I know ,valvesprings were our big nemesis , but being in the wrecking business , we used trade VW parts to Crower for boxes of them. Factory steel cranks held up pretty well although I used to keep an eye on the runout on the center main and have them beat straight again, yeah I said beat not pressed. Vern James a local diesel machinist was adamant about that . If during a season the center main bearing stated showing copper , it was time.We kept a couple spares and some were down .030" but wet magged Ok.

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