Lomax Incidence of cast rocker cover on cooling

[Jack602]

I understand that low by-pass pressures are specified for vehicles where oil changes are likely to be missed, appropriate for a 2cv being run on a budget,, but not for a well maintained Special.
I believe that by pass pressures are set by the filter manufacturer relative to the construction of the filter (how much pressure the filter can take before the element or casing ruptures), I would rather not be by-passing unfiltered oil.
The OC51 filter is the one that Der Franzose supply for their 2cv conversion kit.

Jack
Pembleton Super sport

Attached photo shows the fixture I use on my lathe for machining a 3/4 unf thread in a 2cv filter head,

[Vyv Cox]

I bought the large filter conversion following the article in Flat Out. In conjunction with the oil temperature adaptor the large filter will not fit as it fouls the chassis on my Lomax and even the small filter seems to contact it at times, presumably at certain revs.

[kawlomax223]

I use a smaller oil filter (Ford Fiesta) on the same 3/4" unf adaptor in the winter.
I find with the oil cooler blanked off with Tank tape and using 10/40 oil the engine quickly reaches operating temperature, correct temperature and pressure was maintained on a 70 mile trip last weekend.

Jack

Hi Jack. What are you calling ‘operating and correct temperature and pressure’? As I understand it Citroën didn’t specify operating temperature. Where are you getting this information from? With an air cooled engine there are so many variables... engine load, engine speed, ambient temperature etc.

[kawlomax223]

I use a smaller oil filter (Ford Fiesta) on the same 3/4" unf adaptor in the winter.
I find with the oil cooler blanked off with Tank tape and using 10/40 oil the engine quickly reaches operating temperature, correct temperature and pressure was maintained on a 70 mile trip last weekend.

Jack

Hi Jack. What are you calling ‘operating and correct temperature and pressure’? As I understand it Citroën didn’t specify operating temperature. Where are you getting this information from? With an air cooled engine there are so many variables... engine load, engine speed, ambient temperature etc.

[Lomax76]

I suppose Jack is refering to Citroen data, @80°c the pressure for a 602 engine should be 6 to 6,5 bar (87 to 94 psi) for 6000 rpm..

[Jack602]

Oil temperatures are set by the oil manufactures rather than by make of car, and as such recommended temperatures have crept up over the years.

The modern aftermarket temp gauge fitted to my special shows red below 50 degree c and above 120 degree c.

References below are from two books, both by A. Grahame Bell. These books also cover filters as discussed in this thread, I can recommend either of these books to Special builders interested in engine development from first principles.
The summary notes I made on oil temperature from the Lubrication chapters of these books are as follows:-

Performance Tuning in Theory & practice (Four strokes) (1986 edition)
Min 50 degree C, Ideal 80-90 C Max 150 C for short periods

Tuning New Generation Engines (1988)
SF oil min, 10-40 when air below 15C
Ideal 90 -120C 130C even 140C ok for short periods

Hope this is of interest

Jack
Pembleton Super Sport 602

[Ken Hanna]

Indeed, plus the specified pressure for a Citroen A series engine seems to be higher than for designs of a similar age.
That may be linked to the narrow width of the big end bearings...

Oil at 80*C, M28 and M28/1 engines, 5.5 to 6.5 bar, 78 to 92 psi at 6,000 rpm
.
Ken

I suppose Jack is refering to Citroen data, @80°c the pressure for a 602 engine should be 6 to 6,5 bar (87 to 94 psi) for 6000 rpm..

[Lomax76]

I will not go this route I do not think bearing insertion of a 2cv engine can stand without damage more than 120degree C.
All these assumption are made for modern water cooled engine with adapted metallurgie.
Advice is cheap

Performance Tuning in Theory & practice (Four strokes) (1986 edition)
Min 50 degree C, Ideal 80-90 C Max 150 C for short periods

[Jack602]

Ken,
Do you know what max oil temperatures 2cv racers are running at without engine damage?

Jack

[Lomax76]

Actually I think he does very well.
But now we are getting fare away from the Subject. My point is not to make my Lomax a racer but optimize the performance and the reliability. I am looking for the best MTBF ratio.

Ken,
Do you know what max oil temperatures 2cv racers are running at without engine damage?