just wondering how much should be in the spot where it goes ??
cheers

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PrOuDlY aSkInG qUeStIoNs FoR uR aMuEsMeNt

Fill to the top of the piston rod.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

....and it will find its own level of happiness after that....

I love how every so often, for circumstances I cannot comprehend, it does this by squirting out the bleed holes in the caps and over the engine

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I Had an austin 1300 with the SU on a reversed Manifold that stuck out the bonnet, it sprayed the excess all over the windscreen!

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speed costs....how fast do you want to go...

I Had an austin 1300 with the SU on a reversed Manifold that stuck out the bonnet, it sprayed the excess all over the windscreen

^^ lol GOOD TIMES THERE GUYS...
kool, and thanks ,, just making sure i do things correctly.
fiji

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PrOuDlY aSkInG qUeStIoNs FoR uR aMuEsMeNt

the morris minor I raced had the rear of the bonnet folded up for better air flow. not good when the eng throws a leg out . the sump contents ended up all over the wind screen just when I was in a group of cars in the brakeing area for a corner

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

I was wondering if it goes on top of the plunger or do I pull it out then fill it and push it back in?.

Also how hard should it be to push the piston upwards? mine was fairly hard and quite slow to drop down again.

I pulled the bell off and drained the atf out its back together and the piston moves freely so its not stuffed..


so to highjack, just saves me starting a new thread.

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the su tune up book says to remove the damper plunger, fill the tube of dash pot to 1/4" above[for vented caps ] and level to top for non vented caps

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

do you mean 1/4" below the top of the tube?

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No, 1/4" above the top of the (hollow) piston in the bore.

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Simon

The adventures of an owner builder in the Tallarook Ranges

Quoted from the bible

finally top up the piston damper with recommended engine oil until the level is 1/2"[13mm] below the top of the hollow piston rod.
NOTE: on non dust proof units[identified by a vent hole in the piston damper cap] the oil level should be 1/2"[13mm] ABOVE the top of the hollow piston rod.
END of quote

As most of the su's here have the vented type of cap I only fill 1/4" above. I find that more than that the oil comes out. The level may be OK for a horizontal carby but at 30 deg on a mini carby it WILL come out.

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

Matty,,, don`t go muckin with my tune too much mate,,, it goes good, just wait till you bring her back for the service , then we can both play with things & check other stuff out ok>?

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Fiji and Minidunger,
The cap and plunger has a one way valve on the end. It slows the rise of the piston when accelerating .This is what gives the richer mixture needed for acceleration. When you hit the throttle the piston needs to drop immediately to richen the mixture.
As speed increases the damper allows the piston to slowly rise until the leaner mixture needed for steady speed operation is reached. If it didn't do this the piston will rise too quickly and lean the mixture off too fast causing a flat spot, etc.
Not all cap and plungers are created equal. There are several different types of cap and plunger assemblies, some for different types of SU and some with different plungers and initial free play for different applications.
As long as the plunger is fully immersed in the oil it will work OK. The level should be just above the piston rod to provide some lubrication to the piston rod assembly as it moves up and down.
When you test the piston movement there should be resistance in the up direction and it should drop freely in the down direction. Use either the piston lift pin or stick your finger in the carb inlet and move the piston that way.

Hope this helps.
RonR