Clarke rebal air 60 - fill time

[pondy]

Brought one of these cheap locally, works fine but I'm unsure if it's taking to long to fill up. It is a direct drive unit, single piston pump which I think is 9cfm and 60litre tank. From empty it takes 3 mins and 20 seconds till it cuts off at 150psi. Sound about right or to slow?

It has recently been rebuilt, have an invoice for gasket kit and also have old gaskets so would like to thinks it's all been checked over. Don't want to take the head off to check valve plate if I don't have to.

 

[pondy]

Had a think, my other unit is a 2.5 go, twice the pistons, the Clarke is 1hp and one piston, prob works out fine, having a brain Fart I think

 

[AdrianH]

Not sue if this is correct but 9 cfm is just under 255 litres/min, now if you have a 60 litre tank then in one minute you should be around 4.2 bar if it was a perfect system. After 2 minutes, 8.4 bar.

150 PSI is 10.34 bar and in a perfect world you would make that in 2 mins 28 seconds! But it will never be that good as the pressure increases it will have more problems getting 100% efficiency. To me it sounds OK perfect world it would be 14 bar you are making 10.34 that makes it 74%, not bad in my mind.

Adrian

 

[Tiggy_dorset]

If I recall correctly, the first time I fired up my brand new Sip 150litre, I timed the fill to about pretty much around the same just over 3 minute mark.

 

[pondy]

If I recall correctly, the first time I fired up my brand new Sip 150litre, I timed the fill to about pretty much around the same just over 3 minute mark.

So takes about the same but the tank is 3 times as big. Maybe I should take the head off and see. Is it ok to reuse the gaskets?

 

[Tiggy_dorset]

So takes about the same but the tank is 3 times as big. Maybe I should take the head off and see. Is it ok to reuse the gaskets?

3 times bigger, but I guess 3 times the power maybe? Mine is a 4hp motor. If the ratio of power to capacity is similar, then your fill time works out right perhaps?
I'm no expert, so dont know, just speculating really.

 

[pondy]

Only have a 1hp motor

 

[Tiggy_dorset]

Ill go out now and switch mine on and time it.

 

[Tiggy_dorset]

It was a good time to drain it, so had to do that first. From empty mine has just taken 3m 45s to fill. Ratio of motor power to tank capacity, yours works out more efficient than mine. Mine is a couple of years old but get use very infrequently, oil is still clear as day.

 

[Tiggy_dorset]

Hmm doing the calculations if I have them correct :
60 (litres) / 200 (seconds) = 0.3 litres/second
150 (litres) / 225 (seconds) = 0.67 litres/second

So in theory yours is half as efficient. Have I done the calcs right? I feel Im missing something.

 

[pondy]

Curiosity got the better of me and I ripped this thing apart to see if there is accually anything wrong with it of if it's just me. This is what I have found.

First the intake is very restrictive as its also a muffler, the air needs to travel around a few corners, plan on cutting some of this out to make it flow better not fussed about the added intake noise




Valve plate is all good, slight oily/carbon on one seat. Valves are flat

I checked the end gap on the piston rings, 2 of them were 0.20mm and one was 0.10mm which I think is a bit on the tight side

Lastly the cylinder has a strange mark, running my finger over it I cannot feel it, I can however feel it slightly with my finger nail. I first though it Had cracked but looks ok from the outside so thinking it Sat for some time and moisture has caused some rust. Have gone over it with 400grit paper. Should I be worried about this?





Piston rings are available from China for £4. Is it worth replacing, they can't be to worn if the ring gaps are tight? I would expect oil blow by out the breather which I don't get.

 

[dobbslc]

That looks like a water mark to me. Should be fine I've seen similar in two stroke bike barrels.
Chinese rings?
You'd be better off making some out of baked bean cans.

 

[pondy]

I'm going to clean and reuse the old rings. Put them flat in the barrel and put put a torch around the them and they seem to seal well with no light visible around the edge