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348 Crankshaft

Discussion in 'Technical Q&A' started by fockewul, Oct 23, 2004.

  1. fockewul

    fockewul Rookie

    Oct 23, 2004
    1
    Hello

    I own a 1990 Ferrari 348 TB. Recently, I had engine problems and the crankshaft needs replacement. However, given the price of a new crankshaft, I was thinking if grinding the old crankshaft was a viable option. I've done that before, with good results, but never on a Ferrari. I heard say that Ferrari crankshafts have a low-friction surface layer, that would be ruined if the crankshaft is grinded. Is this true? Can anyone give some advice? Thank you.
     
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  3. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
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    Brian Crall
    All Ferrari cranks are nitrided. That is a surface hardening treatment that is intended to make the crank more resistant to wear and damage. Ferrari cranks can be repaired just like any other. A nitrided crank may require renitriding when you are repairing it so it will cost more but is certainly a process that any quality crank grinder is familiar with. I know that in the case of 308 cranks because of the quantity of them available I can on occasion buy a good used one for less than repairing a bad one. You should shop around and see if that is the case on 348's as well.
     
  4. don_xvi

    don_xvi F1 Rookie

    Nov 1, 2003
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    Don the 16th
    How much have you seen for the price of a 348 crank... any prices for used?
     
  5. Matt Morgan, "Kermit"

    Matt Morgan, "Kermit" Formula Junior

    Nov 12, 2003
    405
    Ferndale, WA
    Rifledriver is on the money with the 308 cranks. As I recall, the manual calls for re nitrideing them after being ground past the second undersize. It is a hard surface treatment common in machine tooling as an example, so what is under it would wear quickly in comparison. Your manual will probably list the same depth, so IMO measure it before going any further. Chances are if you spun a rod or some type of damage of that nature, you will not only be past the second undersize diameter, but you can do some interesting heat treating when spinning a bearing. Check for "blueing" or discoloration due to heat. That will give you another go/no go step. In reality,it could get rewelded, heat treated, oil passeges redrilled, re treated, and reground to the same size as new. But the cost would be no doubt far more than a good used one by probably several times. But the one thing that stops the whole idea is no information on what the crank if made out of in the first place. This makes welding difficult, as you must be adding the same type of material as you are building up the surface, or it will react differently to heat treating, etc. And nobodies talking on tht topic, believe me I have checked everywhere I could. In the "old days" stroker cranks were all welded up stockers, as there as not an after market made one, they didnt exist then, so it was a common and successful practice. If I just knew the 308's alloy, the fun I could have with stroker 308's. lol
     
  6. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
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    Brian Crall
    Never went shopping for one. Try T. Rutlands in Georgia.
     
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  8. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,987
    socal
    Kermitt,

    Try WEB cam in san bernadino, Ca. They have been grinding and rewelding Ferrari cams for years and can probably do a crank too. They know what the metal is. Ferraris have small base circles so you can grind for a new profile like 308 guys going to P-6 grind. So guys like WEB cam do weld grind heat treat as SOP. Nitriding is no big deal now...it is old technology almost anyone can do it.
     
  9. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
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    Malcolm W
    The crankshaft on a 348 can be re-ground for the first undersize without re-nitriding - according to the workshop manual "the surface hardness of main journals and crankpins usually exceeds the minimum requirement" - but worth checking out with the machine shop.

    However for a second undersize the shaft must be re-nitrided.

    See table below for sizes................
     
  10. Matt Morgan, "Kermit"

    Matt Morgan, "Kermit" Formula Junior

    Nov 12, 2003
    405
    Ferndale, WA
    Yes, I am familiar with Lauri's work on cams. I use Web Cam stuff mysellf. I'm not sure that the crank, and the cams are the same material however, and that is still the problem. Logiclly, one would think they are, but to be sure..
    Perhaps Malcomb can shed some light?
    Kermit
     
  11. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    Malcolm W
    Yes, definately a different material, however can't find anyone who knows the exact spec.
     
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  13. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
    5,379
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    Paul
    I do not know what 348 cranks are selling for, but cheapest I have seen 308 cranks has been $900. We are talking a basic 4 cylinder crank, and most shops charge basic machine shop rates based on the number of journals ground. So a Ferrari V-8 crankshaft should be no different than a 4 cylinder anything crank and add in nitriding. I had a 4 cylinder Perkins diesel crank overhauled some time ago. It was magnafluxed for cracks, ground and polished -.010 undersize, and nitrided. I think total cost was about $275.
    If you bought a used crank I would imagine you would want it magnafluxed, polished and renitrided just to be safe, may as well rebuild what you have. That is one very strong crankshaft and I dont know how you would ever break it.
     
  14. zsnnf

    zsnnf Formula 3

    Sep 11, 2003
    1,877

    About $1500
     
  15. brm

    brm Karting

    Apr 26, 2002
    183
    Tampa, FL
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    Bruce R. Morehead
    I do not know if this will work for you but many years ago I had the crank from my AC Bristol industrial hard chromed back to specs when we could not find anyone to renitride it. It lasted until a future owner put a Ford V8 in it.
     
  16. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
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    Are you saying it was "plated" back to size with chrome plating? There is a shop in I think Atlanta, Paeco is I think thier name. They used to advertise welding up journals with chromoly to make them wear better. They would intentionally grind them down about 1/2" undersize (1/4" at surface) and then weld up to oversize and then grind back to standard size and then nitride.
    But, I worked around aircraft for a while and that would never be legal. In fact, once a aircraft crank is below max undersize its junk. I also seem to recall that any bluing from a turned bearing could make the crank junk as well. But I also dont think anyone makes a crank like Ferrari, out of a billet peice of high grade steel. Yes, you can have one made for racing engines, but I know of no other engine manufacture that builds cranks like Ferrari. And I would also think that welding on it would destroy much of the strength intended by building it that way to begin with. Turn it, and renitride it, but dont weld on it. And make sure whoever plays with it knows what the hell they are doing. I had a crank almost destroyed because it was ground bad. Had to have it re-ground and then it was maxed out undersize, so it will never be able to be reground again.
     
  17. brm

    brm Karting

    Apr 26, 2002
    183
    Tampa, FL
    Full Name:
    Bruce R. Morehead
    The Chrome plating was not the bumper type chrome. The crank was ground true and then the special chrome was plated back to spec. The company is out of business now and I do not have any more details on the process. They did a lot of work on industrial equipment in the Tampa area. Of course everything was rebalanced before assembly.
     
  18. Matt Morgan, "Kermit"

    Matt Morgan, "Kermit" Formula Junior

    Nov 12, 2003
    405
    Ferndale, WA
    I believe you are refering to "Hard Chroming", an industrialtype of plating,mostcommonly sn on hydaulic rams, like is on a backhoe forexample. Very durable stuff.
    I hd an experience with Paeco a fewyears back over some Ferrari valves. a fellow named Carl Singfellow and I got into it as he tried to convince me that I could shim hem up to the right seat pressure. He said to use .250" shims. Hell, I have neve seen a shim over .092"! And with that much shim, even ifI fabbed them, it would coil bind the first time I tried to turn the motor over. I explained that to him, and his response was a terse "We only deal in High Performance stuff". Oh yeah,that will help, it will bind @ stock lift, so add a big cam? I would doubt he is still there. "Stuff" got so deep, I had to stop and clean my socks as the shoes were lost,lol.
     
  19. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
    5,379
    NWA
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    Paul
    I never so much as called Paeco, just read thier catalogs when they came in the mail. But your dealings with them sound rather appropriate, as when I finished reading about welding up crank journals I just shook my head.
    Funny how people who obviously should know better, can argue stupidity. I really need to bore my cylinders, but I absolutely do not trust a single shop anywhere in this entire state. I am thinking I will try and locate some good cylinders that arent worn to match my other cylinders ( I have virtually no wear, but three cylinders are scored ), and just hone them all and call it good. Less I allow someone to screw me up, the better off I'll be. Then I will just have new pistons made to fit.
     
  20. Matt Morgan, "Kermit"

    Matt Morgan, "Kermit" Formula Junior

    Nov 12, 2003
    405
    Ferndale, WA
    Say Paul, I have a thought that might help. If you checkout the single liner with Venolia piston I posted on the thread "Wiseco Pistons", as an example of Plateau finish, please note: That liner was one of the ones that L&M had bored straight in referance to the crank, but tapered badly. Mark Huson saved the liners on that whole side. (whew!) I allready have a 4130Chrome moly deck plate, 1" thick surface ground to .0002" and special double length nuts so there is no worrying about damageing the threads. Why not look into shooting it over here, and I'll take it down to him. I'll PM the details
    Kermit
     

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