Mileage between engine rebuilds on WO Bentley

Peter Graham

Would like to know what is the expected mileage between engine rebuilds on a 3 litre or 4.5?
Do engines do a greater distance between rebuilds when modern cranks are used?
Does anybody have any idea what the real impact on engine life that can be attributed to modern oils?
Has anybody done any research regarding the current practice of using oil filters rather than the 1920's strainers.

John Murch · Posted: Mon May 30, 2016 4:06 am Post subject:

What an interesting question, I have no objective answer. However for 'in period' details, some time spent looking through the club archives may reveal the service history of some cars and give a guide to the engine life at that time.
When I had my first 4.5 in about 1974 I was able to establish that it had done at least 400,000 miles, but cannot say how many rebuilds it had been through during that time.
John

Chris Card · Guest

All I can say is that my 4.5L has done 30,000 miles since Elmdown did a comprehensive rebuild, it uses no measurable oil, maintains +/- 40psi oil pressure (drops a bit if very hot), water temperature 160 -180F. starts on the button and pulls "like a train". I have every confidence that it will continue like this for some time to come. Even the mags have been trouble free for several years now.

I know this is tempting fate, but . . . .

Fuel consumption +/- 19mpg with o/drive and 3.3:1 diff.

Reading Bentley service sheets, engines were being de-coked every few thousand miles, so things have changed lot since then.

Chris

Peter Graham · Posted: Mon May 30, 2016 4:20 pm Post subject:

Chris
I admire your 19mpg. The best I have achieved is closer to 16mpg. Overdrive and 3.53 diff. although a light body.
We rebuilt the engine ourselves, we took great care and so far we have done 108,000 miles since we completed the rebuild of the car in 2004. No change in oil pressure or temperature.
I am confident that the robustness of the engine design, modern oil and filtration will help us do even more. I have my fingers crossed.

Chris Card · Guest

Peter - I have twin Slopers with CV needles, I've balanced them as near as I can (with a simple suction gauge), and adjusted the mixture by lifting the pistons to get as little change as possible to the idle speed. I then periodically look at the plugs to check that they have a dark brown colouration to the electrodes after a drive (usually ending by blasting up the steepish climb to our house, in second, before cutting the mags).
I'm running on SU pumps, with an in-line adjustable pressure regulator to minimise flooding from the bowls, as the pumps will overcome the needles, especially on a bumpy road - of which we have plenty round us here, in Surrey!

Chris

David Cocking · Posted: Mon May 30, 2016 7:36 pm Post subject:

Chris, any more details on the regulator type and arrangement that you use? I have been considering the same mod for similar reasons.

Chris Card · Guest

David - Purolator Pro-Fuel adjustable fuel flow regulator and it is in the petrol line (in a short section of flexible fuel line to minimise vibration, as it is unsupported) just below the bulkhead, where it is accessible for adjustment. I have it set at 1.5 on the scale, and that seems to work fine.
It comes in fuel line sizes of ¼; 5/16 and ⅜.

Chris

David Cocking · Posted: Tue May 31, 2016 5:35 pm Post subject:

Perfect, many thanks Chris.

Stephen Blakey · Posted: Tue May 31, 2016 8:58 pm Post subject:

The alloy bowl version of the Filter King has a somewhat period look;

http://www.fuelpumpsonline.co.uk/malpassi-filter-king-fuel-pressure-regulator-85mm-clear-or-alloy-36-p.asp

David Cocking · Posted: Tue May 31, 2016 10:46 pm Post subject:

Spoilt for choice! Many thanks Stephen.