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Inside Plug/Outside Plug

Discussion in 'Vintage (thru 365 GTC4)' started by Maximillian575GTC, Feb 2, 2009.

  1. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    romano schwabel
    I think the 250 GT is more agile on curvy roads because of the shorter wheel base an dthe 250 GT/E i snetter to go straight
     
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  3. miurasv

    miurasv F1 Veteran

    Nov 19, 2008
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    Same 2.6 m wheelbase. Engine moved forward in GT/E.
     
  4. turbo-joe

    turbo-joe F1 Veteran

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    oh? I thaught also the wheelbase changed. so learning again new things here.
    this with the engine I had known
     
  5. TTR

    TTR F1 Rookie
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    Gentlemen, perhaps incorrectly, but I think Henk was referring and looking forward to performance comparison, feel, etc between inside/outside plug engines, not the chassis.
     
  6. Ferrari_250tdf

    Ferrari_250tdf Formula Junior

    Mar 3, 2005
    357
    It is always more about the car as a package than the engine alone. If you want a real comparison, you have to drive maybe a Boano first with an inside plug engine tipo 128 C with let's say 240 hp, then take out the engine and put an outside plug tipo 128 F also with 240 hp in and drive again. I bet, there will be no difference in the driving characteristics.
     
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  8. John Vardanian

    John Vardanian F1 Rookie

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    #31 John Vardanian, Jan 30, 2021
    Last edited: Jan 30, 2021
    To me, the IP throttle response is more sewing machine like.... going back to when I waited till mom walked away from her Singer and I'd put my foot in the electric pedal and pretend I was Phil Hill. Boy, that pissed her off to no end.

    john
     
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  9. Lowell

    Lowell Formula 3
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    I hope that I am not repeating something already explained on this thread. Anyway:

    I had thought that the original Colombo engine had 1.5 liters because it was meant to be a supercharged F1 engine which had a 1.5 liter limit. Mouse trap springs were chosen to reduce the valve weight so they were easy to open and close fast. But this did not leave much space on the heads so that (fewer) studs had to be placed in such a way as to not leave much space for the intake ports that then had to be siamesed. This reduction in flow was of no concern because of the supercharging.
     
  10. DWR46

    DWR46 Formula 3
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    Jun 19, 2012
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    Mousetrap springs were chosen because no "coil" springs of that era were reliable at the rpm the engine was capable of achieving. A mousetrap spring also has the advantage of applying consistent pressures throughout the valve opening and closing events.
     
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  11. Admiral Goodwrench

    Admiral Goodwrench Formula Junior

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    readplays and TTR like this.
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  13. turbo-joe

    turbo-joe F1 Veteran

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    the only thing they are bad is at higher rpm`s
     
  14. Glassman

    Glassman F1 World Champ
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    I specifically sought out an inside plug 250 when I bought my first vintage ferrari. I wanted all the experience I could afford, pre 60's car, inside plugs, interesting and documented history, etc. I was very happy with my choice and had a great time with that car.
     
  15. TTR

    TTR F1 Rookie
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    Reading some of the comments/replies here and elsewhere, I’ve been wondering if anyone more acquainted with the hairpin-to-coil spring conversions done on early engines would have an (percentage) estimate on how many have received this treatment ?

    Also, does such conversion/treatment add or subtract from perceived resale value or have any affect on point scoring at IAC/PFA level judging ?

    Just curious.
     
  16. DWR46

    DWR46 Formula 3
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    Timo: Without the cam covers removed, you cannot tell if the conversion has been done, so no effect on judging. I know quite a few motors have been converted since we began doing them in the mid 1970s. The problem then was no supply of factory hairpin springs. There were repros available then, but they failed almost immediately in service. I believe there are now good quality hairpin springs available. The original springs wear where the retainer rides on them and that is why they go bad. However, I have seen springs almost 1/2 worn away and still functioning perfectly. When we encounter a motor with hairpins, we almost always convert them to modern coils. You will probably need new valves anyway, so might as well have modern reliable parts that will run for years.
     
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  17. TTR

    TTR F1 Rookie
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    Dyke,
    Thanks for your insight.

    I know/realize the visual inspection or verification of original design/construction details or features inside any mechanical components are not feasible/possible during judging, but as someone who often "struggles"(?) to support justifications for some improvements or upgrades, I just find these issues intriguing.

    Would I be fortunate enough to face this particular "dilemma" on my own, I'd probably modernize it too to maintain practicality and safe use, but would probably look into spare, perhaps reproduction(?) heads or entire engine to do it with and leave original ones "as built".
     
  18. turbo-joe

    turbo-joe F1 Veteran

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    why not use new heads instead of modifying the old ones. because so you could save the old ones and pee then original
     
  19. JimEakin

    JimEakin Formula Junior
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    Regarding engine responsiveness for IP vs OP: what about flywheel weight? Lighter flywheel, quicker response.
     
  20. turbo-joe

    turbo-joe F1 Veteran

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    sorry, misstyping: wanted to write ..... and keep the original
     
  21. DWR46

    DWR46 Formula 3
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    Joe: In the 1970s, there were NO "new" heads, either original or reproduction. Good quality repro heads have only been available in the last 15 years or so. Also cost is a major factor with modern valves being easily custom made here for very reasonable prices and off-the-shelf valve springs not costly. You can convert MANY engines for the price of a pair of new repro heads.
     
  22. Edward 96GTS

    Edward 96GTS F1 Rookie
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    once converted, can it be reversed to original if so desired(even if not a good idea).
     
  23. DWR46

    DWR46 Formula 3
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    Ed: You have to do some careful machining on the head, and while I never tried, this could make reversal more complicated. There is NO reason to ever go back to hairpin springs.
     
  24. 635CSI

    635CSI Formula 3
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    If anybody would like a properly produced and bound full colour re-print of the “outside plug” 250 GTE manual..feel free to drop me a PM ;)
     

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