V-12 Engine into 308 Build, over on Grassroots | Page 7 | FerrariChat

V-12 Engine into 308 Build, over on Grassroots

Discussion in '308/328' started by dave80gtsi, Jan 16, 2019.

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  1. derekw

    derekw Formula 3
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    I looked up the thermal expansion of Ti 6AL-4V and was surprised it's about 8% less than 4340. So you can perhaps run the big ends a little looser than steel rods?
     
  2. mk e

    mk e F1 World Champ

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    Maybe. The factory 355 spec doesn't appear looser but its a stack-up spec.

    so even when things seem done on this....they aren't. The center 5 head studs on each side are original in their original location, the rest are relocated custom studs. the TR heads are not quite as tall as 400 heads so I knew the original studs were on the long side.....and it turned out a couple not quite ok.

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    So as long as it was still on the bench might as well have at the offending studs so I don't need to think about that anymore......
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  3. mk e

    mk e F1 World Champ

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  4. mk e

    mk e F1 World Champ

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    Block and crank at the shop.
    I told them:
    clearance rods and mains .0021
    Pistons .003

    3-4 weeks which should be plenty of time to get everything else ready...in theory anyway
     
  5. mk e

    mk e F1 World Champ

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  6. Brian A

    Brian A F1 Rookie

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    Go slowly and carefully.

    I thought you said this project is supposed to last your lifetime. :p
     
  7. Ferraripilot

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    Nice! Mark, remind me why this masterpiece needed to come apart again?
     
  8. mk e

    mk e F1 World Champ

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    #158 mk e, Oct 13, 2020
    Last edited: Oct 13, 2020
  9. mk e

    mk e F1 World Champ

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    hypothetically, if the engine runs properly in a few weeks there will still be plenty to do to the car.....many more years of projects to get it where I want it to be so no worries about running out of work. The real issue is I'm not sure how long my honey-do break will last so I want to push a bit to at least get it running :)
     
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  10. Ferraripilot

    Ferraripilot F1 World Champ
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    gracious! well ok. carry on. Can always be worse right
     
  11. mk e

    mk e F1 World Champ

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    In the heat of battle its pretty easy to see only the big issues and mis the smaller ones. Years ago when I was roadracing motorcycles I would do the crazy fab and a buddy would do the final assembly so the details got fresh eyes....he'd come from construction and did the same with his 2 crews....move a new crew to the jobs once the finish work starts so they aren't tired of the place and just want it done. That worked out well.

    I missed way too many of little things in my push to finish the 1st time around.....but now that I know all the parts can actually be bolted together to make a working assembly its much easier to stay focus on things like do to the valves fit right? not just do the valve fit at all, and after a replacing a few wonky guides I should never have installed and a couple hours with a guide hone they do. I've got at least 3 weeks to focus on the heads before the block and crank are back so they should be right.

    Then more stuff to check once the bottom end is done to be sure the top and bottom go together right just just do they go together. Probably a couple weeks checking stuff then a final assembly and it should run properly. I started this project when my older son was 6 months so neither of the kids has ever seen the car run....he (older one) is 13 now. My how time flies :oops: .... but both kids are getting pretty exited to see it drive which helps keep Lana...well not on board exactly but not a solid no....for the moment.
     
  12. mk e

    mk e F1 World Champ

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  13. mk e

    mk e F1 World Champ

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  14. Newman

    Newman F1 World Champ
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    Curious why you chose the same clearance for rods and mains? The rule of thumb is .001" for 1" of diameter. This even applied to my Indycar 3.5L V8.
     
  15. mk e

    mk e F1 World Champ

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    Its a few posts back but I went around on this a bit. The factory 308/400 spec has the mains about 1/2 thou TIGHER than the rods. 328 and newer have the mains at about 1/2 the rods....1.3 vs 2.6. The best I can figure is the block is stiff and also aluminum so they stay round and grow faster than the crank vs the rods that flex and in the case of Ti get tighter with heat.

    I'm not in anyway claiming to know I made the correct choice. Its on the tighter side for factory rod spec and looser for the crankspec....just the opposite of what you'd think it should be which is why I was confused....but 2.1 is in factory spec for both and I just couldn't bring myself to set the mains tighter than the rods....so 2.1 it was.
     
  16. derekw

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    Aluminium blocks’ mains expand 1-1.3 thou when hot (saw these numbers on some American V8 racing chats)
     
  17. mk e

    mk e F1 World Champ

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    That would definitely put the mains on the loose side when hot. It's 2.479, starting at 2.1, add 1.1 middle-ish expansion so 3.3ish hot = 1.33/inch

    Figuring the rods tighten 6% they end up at 1.1/inch. Its I set them at factory nominal they land at 1.4/inch...which says it I want to be consistent I should set the rods a bit looser as ferrari specs but everything is very loose from the bearing makers baseline numbers of .75-1/inch
     
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  18. mk e

    mk e F1 World Champ

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    Ok, changed to
    crank 2.1
    rods 2.4
    pistons 3.5

    Final answer
     
  19. mk e

    mk e F1 World Champ

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    To figure-out where the exhaust seat depth was originally I cut a seat, put a valve in with its shim and bucket, dropped the cam in and checked the clearance to see where I was relative to where it used to be. The shim was on the thin side so I added .010 to get give me more room to work shim wise....which made me realize why I picked the depth I did on both intake and exhaust, the way larger valves need to be at least that deep for the seat to actually cut on the outer edge so it all worked out fine.
    As I was grabbed the cam it was in my mind that like the valve guides I reamed the journals and called it good so OBVIOUSLY I plan to MEASURE the journal sizes before assembly this time so that is what was on my mind as I dropped the cam in....that's odd.....it pops it with what looks and feels like flex in the cam ...hmmm....I know I milled the journals straight after I finished welding last time.....or was that before I realized the exhaust ports needed work? either way, tonight I'll blend the new seats on the other head then have a good long look at the cam journal situation.
     
  20. derekw

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    are those long heads still straight when torqued down? I was surprised that my 308 mains weren't concentric without the heads torqued down (and the block seems less slender than those long V12 heads.)
     
  21. mk e

    mk e F1 World Champ

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    don't know but that is a small number and probably 90 degrees to the what I noticed with the 1 cam I tried....it was enough flex to see and feel, not just the normal "this feels a bit tighter now that its all torqued" kind of thing you usually get from torqueing that is nice to fix. This needs attention before I can proceed to assembly I think.
     
  22. Newman

    Newman F1 World Champ
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    Ive been ignoring shop manual specs for clearances because we know a lot more today then way back then plus the materials are different today. Piston to wall, ring gap, guides and bearings we go with what we know works and after all it is just an engine (a cool engine).
     
  23. mk e

    mk e F1 World Champ

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    The exhaust cam fit issue wasn't as bad as I feared. The intakes were fine and I went looking back at the pics I'm pretty sure I basically finished the heads then realized I couldn't get the exhaust flow I was after without a little welding in the ports....and that seems to have pitched the cam. A few minutes per head with a ground bar (doesn't everyone have a ground just under cam journal size bar kicking round just waiting for a purpose in life? )and lapping compound and the exhaust cams are like budda. On to fitting the valves I guess.
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  24. mk e

    mk e F1 World Champ

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    I'm with you as much as it kills me to ignore a factory spec :confused:

    The pistons are getting what the piston maker is asking for straight from the piston card. They should be good.

    The valve NOW have what the valve maker is asking for as a general spec....maybe a bit on the loose side as I would rather burn a little oil than repeat the disaster.

    The rods and mains.....I don't know. I know know the factory specs just keep getting tighter so they can spec thinned oil and make a bit more power or save a bit of fuel....My goal, which I'll honestly never know if I achieved, is to get both the rods and mains happy with the same weight oil. I think both the rods and mains at the numbers I spec'd will be about .0013/inch when hot and both want at least 10-40 and probably 20-50....but to you're point I will really never know as I don't have factory development team money and instrumentation and I can;t imagine I'll ever actually run this thing hard enough to find the weakest link to make adjustment based on data.....its just a guess :(
     
  25. Newman

    Newman F1 World Champ
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    Two schools of thought on that. Ferrari says to do that with the head torqued on and I believe its best as well. Ive seen some torque the head to a steel plate which to me makes no sense. Its the liner protrusion that distorts the head and Ive seen lash change with a head on the bench vs on the engine. The fun just never ends.
     
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