Ruston & Hornsby 2 1/2 h.p Type PR

Discussion in 'Help Wanted' started by picklesquirt, Aug 30, 2016.

  1. picklesquirt

    picklesquirt Member

    Hello all,

    Some advice please, I have a type PR engine, with Bosch flick mag. It is fitted with a Champion k17 plug and runs quite happily on petrol but will not keep running when I switch over to paraffin ( 28sec kero ) even with the hopper boiling. Engine puffs white smoke i.e. un-burnt kero.
    The plug looks quite new and appears to have a reasonable spark, does one need a better spark to fire paraffin and is this the best plug to be using.

  2. petternut

    petternut Administrator

    A K 17 is not hot enough IMO. Try a D21.

    good luck
  3. picklesquirt

    picklesquirt Member

    Thanks Roland,

    I'll go after one.

  4. lambe

    lambe Member

    Could low compression be a contributory factor in poor vaporisation and firing?
  5. picklesquirt

    picklesquirt Member


    I don't know much about the internals of this engine, it was too good when I bought it at auction. I have tried to contact the previous owner via the auctioneers but nothing was forthcoming. I would say the compression is good, very difficult to turn it over past compression with no obvious hissing.
    I have ordered some D21's .Will let you know what success or otherwise.

  6. highrange

    highrange Member

    Don't know much about paraffin/TVO engines (other than my uncle's old Fordson almost 60 years ago!), but I suspect white "smoke" is unvapourised paraffin ...... is the vapouriser in good order?
    (I'm assuming it's something like the Lister D arrangement using exhaust heat ??)
  7. robtheplumb

    robtheplumb Member

    I reckon you have an issue with the needle and seat on the paraffin side, that is assuming you have ran it for ages by topping up the petrol bowl and have paraffin in the tank.

    White smoke is normally a sign of being to cool when switching to paraffin, my M type Petters will do this along with popping and farting until they get nicely warmed through.

    As a trial, try a 60/40 mix with petrol, see how it goes with that.
  8. picklesquirt

    picklesquirt Member

    Hi all,

    The D21's arrived today, it's a different engine now happily running on 100% kero.
    Many thanks Roland and all others who commented.
    Is the D21 also good for the Petter M type?

  9. petternut

    petternut Administrator



Share This Page