Oil Pump size

Discussion in 'Mech Tech' started by jmarchant1970, Dec 11, 2019.

  1. Hey people
    I am assembling a 1600 tp engine which includes mostly new everything.
    I bought the case at "Slough" from the Heritage table, they did me a god deal on bearings etc as well.
    The guy on the stand said I would be better off going with a 30mm geared oil pump to improve oil pressure. I am using a 4 rivet cam shaft.
    What are you guys thoughts on this?
    Cheers

    John
     
  2. Stock .
    I'm no mechanical guru but too much pressure isn't always a good thing , especially when the engine is new , cold and the oil thick .
    Just my tuppenceworth , other's will obviously disagree

    Sent from my SM-G960F using Tapatalk
     
    jmarchant1970 likes this.
  3. 77 Westy

    77 Westy Supporter

    The guy is wrong, in my opinion. Why do you need to ‘improve’ the oil pressure?

    The oil pressure relief valve controls the pressure and a standard pump should be fine for an engine in good condition, or 26mm if you have an external oil cooler. If you do use a 30mm pump use light oil, 5w30 for instance.

    If you fit a 30mm pump and use normal weight oil the pressure will be high, the system will think the oil is cold and by-pass the cooler to thin the oil and reduce the pressure. You’ll end up with hot oil at normal pressure.
     
    Lasty likes this.
  4. Makes sense.
    I think I will give them a call and swap for a 26mm.

    Thanks for the advice

    John


    Sent from my iPhone using Tapatalk
     
  5. 77 Westy

    77 Westy Supporter

    Ask him why you need to improve the oil pressure and how a bigger pump would achieve it. Then buy the 26mm pump.:)
    Incidentally, carefully check the fit of the pump in the crankcase, it should be a slight interference fit, if it slides in and out easily it’s too loose. Aftermarket pumps are invariably undersized on the OD and leak internally – maybe that’s why he’s suggesting a larger pump.
     
    Last edited: Dec 11, 2019
    mcswiggs and snotty like this.
  6. Worth noting that your oil pressure will depend on whatever restrictions are further downstream (ie your bearings), not necessarily the pump.
     
    77 Westy likes this.
  7. 77 Westy

    77 Westy Supporter

    Yes, if you have very large bearing clearances a bigger pump may be required for additional volume, not additional pressure.
     
    Last edited: Dec 11, 2019
    snotty likes this.
  8. mikedjames

    mikedjames Supporter

    If all you are building is a 1600 and you have a brand new case then 26mm is the biggest pump worth bothering with. That should be good for an easy 45psi hot running (relief valve lifting pressure, not what the pump can deliver) and 20psi hot idle.

    I have a 26mm CB Maxi 3 pump (no drill full flow) on a JK preservation Parts 1641 engine which has about 10000 miles on it.
     
    jmarchant1970 likes this.

Share This Page