Oil Pumps

[wilf]

I have seen many an oil pump drive shaft twisted to destruction on US V8s where people have fitted HP oil pumps unnecessarily.

If you have ever spun up an oil pump with an electric drill to prime an oil system, you will know how fierce the drag is as the pressure builds up. I have burnt out a drill before now doing that when I really wanted to see oil up at the rockers (although it may well have been close to knackered if I am honest!)

This isn't theoretical stuff- it is experience!

[jbuckl]

Andy, please be aware that extra oil pressure can cause the chain tensioners to wear out much, much sooner.

Dave,
Could it be that Robsport are flogging off Heavy Duty pumps and advising a change of relief valve spring, or am I being a little sceptical in doubting their integrity?
I stand by my previous comment and if you can prove that the loading on the County GLP 106 oil pump drive train, probably the square root of F.A., is any higher than a standard Holborn Easton pump I will concede. Anyway how are you going to prove it?

[Stagsongas]

Too much Oil Pressure can also promote the development of leaks, something the Stag doesn't need any help with!

[DJT]

Dave,
Could it be that Robsport are flogging off Heavy Duty pumps and advising a change of relief valve spring, or am I being a little sceptical in doubting their integrity?
I stand by my previous comment and if you can prove that the loading on the County GLP 106 oil pump drive train, probably the square root of F.A., is any higher than a standard Holborn Easton pump I will concede. Anyway how are you going to prove it?

Andy,

I can't prove it, and have no intention of trying. There are people on here far more capable of doing that than I. Which is why I stated that the jury is still out. I will though stand by my statement that the OE pumps made by Hoborn Eaton produced the pressures I've quoted from new. SAAB produced a higher pressure version of the same pump for use on their 4-cylinder versions of the "Triumph" engine, but these engines were subsequently modified well away from the original Ricardo design. The only 'new' Stag oil pumps that have been available from all the suppliers for several years now are made by County and have stronger springs. There are many discussion threads on here about the pros and cons with photographs of the various springs that may be encountered, and Robsport are only stating what other suppliers fail to.

If you are happy with that high pressure, then so be it. I know that I am more than happy with the OE spec pressure, and have been for many years. Several years ago I acquired a large quantity of old Stag OE pumps and when I let other members know of this there was quite a scramble for the old springs which were used to replace County ones.

[flying farmer]

Dave,
Could it be that Robsport are flogging off Heavy Duty pumps and advising a change of relief valve spring, or am I being a little sceptical in doubting their integrity?
I stand by my previous comment and if you can prove that the loading on the County GLP 106 oil pump drive train, probably the square root of F.A., is any higher than a standard Holborn Easton pump I will concede. Anyway how are you going to prove it?

A further problem with the higher pressures involved is the effect on timing chain tension. The extra pressure pushes the tensioners out with more force increasing the tension on the chains. I think this is more of a problem with the current County tensioners as they have a smaller spray hole in the shaft of the tensioner rather than the larger hole in the rubber face of the original items, and this allows a greater build up of pressure.

Tony Hart recommended a maximum of 45psi at 3000rpm when I was asking him for info regarding building a high performance Stag engine. Since he has probably forgotten more about Stag engines than most of us will ever learn, then I will be guided by his recommendations.

Neil