74 replies to this topic

[mike.]

I've just had my newly built engine running. The engine has had all new bearings, new cam kit with high capacity oil pump has been fitted and ball bearing oil pressure valve.

I've had the engine idling on my newly installed megajolt ignition, which isn't wired to the rev counter so I can't tell you any RPM figures. I'm guessing its been idling between 1000rpm and 2000rpm, i've been using my hands on the choke/throttle as they're not connected either.

My oil pressure gauge is reading off the scale. The gauge goes up to 100 and the gauge whips straight round to that as soon as the engine is cranked over a few times and stays there when idling. I've only had the engine running for around 30 seconds, because once i'd seen the gauge I turned it off in case I was going to damage something, so these readings are from stone cold.

Any ideas? I've done a search and read about the adjustable oil pressure valves and cutting down springs but wanted some opinions on causes of this first.

[samsfern]

is it an electronic gauge? Do you know if the gauge is definately good?

Maybe try a standard oil pressure relief valve, thats what id do first, never have liked the idea of a ball bearing....

Edited by samsernie, 07 July 2010 - 07:20 PM.

[carts60]

The gauge might not be wired right. Mine did exactly the same when i wired it in initially because i hadnt connected the sensor to a good enough earth. It came on and went straight past 100 and stayed there no matter what i did like you. Took me ages to realise what was wrong because i thought it was odd that iv done a years worth of perfect driving that wouldnt have been possible if the oil pressure was that high.

Try that first.

[bmcecosse]

Reduce the length of the spring on the ball bearing. The BB relief valve is good - but you do need to adjust the spring - aim for no more than 80 psi oil pressure. I'm assuming the gauge was good before - and nothing has been changed ?

[Darkscamp]

I had the same problem and cured it by still using the ball bearing but using the spring from a normal relief valve. Perfect oil pressure ever since.

Until i run out of oil that is .

[Kerrin]

Reduce the length of the spring on the ball bearing. The BB relief valve is good - but you do need to adjust the spring - aim for no more than 80 psi oil pressure. I'm assuming the gauge was good before - and nothing has been changed ?

As above.

I needed to cut at least a full coil off the end of my spring, to get it down to 70psi, with the ball and spring kit.

But planning to change back to the standard alloy cup and spring as a few people have concers about the ball and spring combo in a road car.

[mike.]

The gauge was bought second hand, but was new in packaging etc. Its a mechanical smiths gauge - So can't be the wiring...

So how much should I cut off to start with?

So if im aiming for 80psi - Is that from cold at idle?

Edited by mike., 07 July 2010 - 08:09 PM.

[samsfern]

if the gauge has a pipe going to it, then its a mechanical one, and therefore doesnt need an earth.

[Wil_h]

Bin the ball bearing, fit the standard 'bullet' valve and all will be well.

I found the ball bearings gave inconsistant oil pressure through the rev range. But as above you need a shorter spring if you want to use the ball, I think minispares sell a shorter spring.

[mike.]

Right, cheers guys. I'll try cutting the spring tomorrow and see how that goes and i'll order the normal bullet valve kit just incase...

What sort of oil pressure should I be aiming for? Other members on here and in past threads have said aim for about 80psi, 60psi and then theres articals out there from the likes of keith calver saying aim for 25psi at idle and 60 whilst driving. What is a safe level of oil pressure to run at idle and what should that increase to when the revs rise?

Another quick question; once i've got my engine running with nice oil pressure, what do I need to know about bedding the new cam in. From what i've heard its simply running the engine at fast idle for 20 minutes - Is this right?

[samsfern]

to bed the cam in i normally keep the revs over 2k, and dont let it idle, or let it sit at a constannt rpm, for 15 minutes, whilst watching the temp and oil pressure, other people may do it differently, but thats how i normally do it.

25 psi will be fine for idle, and 50- 60 psi when driving are what i normally go for on a road engine....

Edited by samsernie, 07 July 2010 - 10:20 PM.

[mike.]

OK thanks. Well i'll see how I get on with this spring tomorrow.

Why do peoples opinions on oil pressure vary so much? I'd of thought it's a pretty crucial thing to get right, but from what it seems as long as its not ultra low or ultra high its fine.

[Dave33]

Peoples oppinions always differ with regard to most things that are adjustable/variable,this is normally based on what they run and have had no probs with or what someone else recommends.
you wont damage the motor by running 70 to 80psi hot while driving,50 idleling but its not necessary.
you mention what Keith Calver says regarding oil pressure,samsernie runs this on his and i run a bit higher than this,around 40 hot idle,and 60 driving,with no detrimental effect.
You need constant pressure not high pressure.
I would take note of what Calver says,as he does explain why this is, not just recommends a figure,and reading through it makes sense.
I personally have not had any trouble with the ball type relief valve,i also use an adjustable type from minispares.
You can through trial and error cut the spring,but its easier and quicker with an adjustable type,and you can do it with engine running and someone watching the gauge.
hth
dave

[mike.]

I thought this but it says on minispares that valve will not adjust idle pressure...

[samsfern]

when i build race engines at work, i normally try to aim for 75 psi, dont worry about the idle as race engines are rarely let idle, if they even do idle, 75psi when full chat, thats what ive been taught anyways. But that sort of pressure isnt neccessary on a road engine, unless your over 5k all the time, not that i will be with my new engine
im not a big fan of the ball bearing thing, personally id chuck it in the bin and fit a standard one.
customcart on here told me a way of making the oil pressure adustable, might be worth pm'ing him...

Edited by samsernie, 07 July 2010 - 11:31 PM.