Oil Pressure - Speedy

[Mark Dymond]

Today, under the reassuring escort of another Austin 7, I drove my Arrow for it first "longer" drive. This car has a unmodified pressure fed "speedy" engine with the big sump so this was probably the fist time the oil had reached a good operating temperature. Oil pressure dropped from a good 30 PSI (cold) to under 20PSI (hot at cruising speeds). Is this a concern, not sure what is normal, or indeed if if the gauge is accurate!

[Chris.Dallas]

Hi, my only experience is our unblown ulster which with an Austin oil pump I get 50-55 psi oil pressure which drops on idle.

I did end up making an adjustable oil pressure relief valve as otherwise you PSI is reliant on the spring only.... 

I was always advised minimum 50 psi.

Regards

Chris

I forgot to ask what oil your using.... I am running on Millers R.

[Chris KC]

I have no experience of Speedy engines but I do run a pressure-fed 3-bearing engine with deep sump.

The oil pump is A7 but with slightly increased eccentricity.

I generally expect to see 50 psi on cold start dropping perhaps to 35 or so at idle when hot.

If feeding big ends from the front of the shaft 20psi sounds a bit low to me.

For what it's worth, I measured oil temperature a while ago with a deep sump - in winter - and even after an hour's run it didn't rise above 60 or 65 degrees, which isn't really hot enough. If using a deep sump I suggest putting less oil in it (i.e. filling only to standard oil capacity).

[Nick Turley]

Hi Mark

I ran my Speedy sucessfully until recently for many years and I would like to suggest that your oil pressure is a very risky low !

Remembering that you have to get the oil to number four big end all the way from the front - a big ask at high revs.
Centrifugal force is fighting you !

My opinion is that a happy Speedy reliable engine in it's original condition would show 50/55psi cold reducing to about 30psi when hot. That is totally OK and safe.
If not, then I would look firstly at the seals at the front. The originals were leather (sprung loaded) - not very good !
I found it was a good to modification to have modern lip seals in the nose.
Having the nose properly centred on the dog is essential.
The surface of the dog has to be spot on.
Once in position I found it a good idea to put a couple of small locating pins into the nose/crankcase flange joint. 
This of course keeps the nose in position and ensures that if it is removed in the future it goes back centrally. 
Quite a bit of faffing about involved but well worth it.
In this original format I would use a good non detergent 40 grade oil as Austin recommended.
With this setup I changed the oil very 500 miles.

If you want to "improve" on that, I would fit a filter into your oil system. Should you go down this route you must have a better oil pump (more flow is what is needed not just pressure) and an adjustable relief valve. 
The great thing about this set up is that you can then use a full Silicon oil like Mobile one for example. 
It can then stay in the engine for a good length of milage (say 2000).
Also the pressure can then be set a lttle bit higher. 
Mine with this set up was set to cold (mobile one oil) 55psi and dropping to 40/45 psi hot. This is plenty enough pressure don't go for more, it does not need it, and you would be  putting unnecessary  strain on the camshaft drive gear.
With this set up you finish up with a very reliable engine that you can drive hard without worry.

Good luck, if you are not sure get expert help - your engine is not replaceable.

[dickie65]

I would suggest that you fit an adjustable oil pressure relief valve, they are available to fit in the OEM position but will require the engine to be removed and oil pressure set up with the engine bench tested. A stronger spring or a bit of packing behind the spring should up the pressure.
I have found that the camshaft oilways and bushes will lose a lot of pressure. I have fitted restrictors to reduce the oil volume to the camshaft. the original drillings were for 5/10 psi
My pressure fed engine drops down down to 25 PSI hot tickover and runs at 60 PSI it has a Pigsty oil set up and an Allen Crank.
As mentioned a straight 30 or 40 oil would help.

[Ian Williams]

My Speedy engine with the seal and pressure valve issues attended to, and a slightly overbored oil pump runs a good 60 psi hot, I also attended to leaks around cam shaft bushes. Personally I think it would be wise to pull yours out and inspect the points raised and the bearing clearances before you do any damage.

[Mark Dymond]

Thanks all, I'll check the gauge then see if the relief value responds to adjustment. If not ill pop the engine out and look at fitting a seal on the nose, there was definitely some wear there when I assembled the engine. Camshaft bearings looked good though.

[Chris KC]

Sounds like a faff but I'm sure it's well worth taking the trouble to get it right.

[Mark Dymond]

Alarmingly its a year on and I have just go around to pulling out the engine to inspect. Nothing obvious wrong with the internals but the oil pump does look like it has seen better days. My thinking is to

1. do the flow restriction "fix" to the cam shaft bearings
   
2. re-machine the oil pump to give a bit more capacity and repair the poor surface finish
   
3. improve the oil seal around the starting dog (not sure how exactly)
   
4. fix a Phoenix crank shaft (I must be becoming more risk adverse in my old age)
   

So my questions are

on the oil pump, Ive 0.005" clearance between the bottom of the vanes and the bottom of the pump and about 0.004" clearance between the vanes and the slots in the drive. "feels" a bit much, what should I looking for in inspecting the pump.

Any details on what has been done before with respect to the nose cone improvements

Anything I should watch out for with respect to the Phoenix crank before I order this.

[Lowespeed]

While you have the engine apart; rotate the rear cam bearing and reduce the size of the oil hole as well. Also machine and fit "o" rings to the front cam bearing.