Interesting. I had the valve out to inspect the inlet chamber for debris, and there was no washer there at all. If I remember correctly it's supposed to be a little fibre washer, but fitting one will only lower the fuel level, so how do I raise it?



If only this float had that little metal bit



OK, that's where I'm going tomorrow then



I reckon you're spot on, I'll grab a new float and valve tomorrow and report in.

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Simon

The adventures of an owner builder in the Tallarook Ranges

OK do you have a float like this or one that has the solid plastic arm.
The needle valve does it have the little spring in it or the solid type.
The spring type needle goes with this type of float. AUD 9202.



The needle with spring was a later idea to help the bowl to maintain a constant level and stop fuel surge into the bowl and fuel airation.
This the little metal bit I was talking about. Some of the earlier carbys had the solid needle and a metal arm that the float clipped into.
The float in the pic is available from fuel miser stock. Check when you get the kit.
The fuel miser kits have a different set-up for the fuel to jet feed. They have a brass fitting that screws into the bowl and a rubber pipe with a spring on the OD that pushes onto the fittings. The instruction sheet has detail of fitting

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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

What I've got is the solid plastic float, no metal arm. The needle assembly has a plastic shell which looks roughly like an 'x' along the long axis, with a brass cone at the valve seat end and a sprung brass pin which the float acts upon.

No idea if this is what's supposed to be in this carb, I don't have another at hand to compare against. From memory I've fitted solid brass needles in the past, but my memory is awful at the best of times...

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Simon

The adventures of an owner builder in the Tallarook Ranges

The spring type needle goes with the float in the pic. the floats have different heights on the point that it pushes on the needle.

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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 thought the plastic float with metal bit pictured was superseded by the 1 piece plastic float??

I use the Oz Fuel Miser kit SU-750, never had a problem with them but often need to leave out the alloy seat washer supplied.

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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.

Are you 100% sure it was an ADF needle before?
Do you have extractors or larger exhaust on the car?

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It was most definitely an ADF which came out of it when I got it, except it resembled a 2-minute noodle more than a carb needle

First thing I did was bash it straight while waiting for the replacement to arrive, that made a huge difference right there. Only reason I knew to order an ADF was that's what was in it.

I've not measured the exhaust, but I reckon it's 1-1/2".. fed by a set of short 3-1 extractors. Intake manifold is a sawn-off standard cast iron item.

I didn't get chance to pick up a new float & needle/seat today, so that'll have to wait until next week now.

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Simon

The adventures of an owner builder in the Tallarook Ranges

I had similar issues on nav. had the carby rebuilt but at the same time put on extractors and a 1 3/4" exhaust. Was perfect at idle but would lean out big time at 3k rpm+. the needle wasn't rich enough so it gave fuel starvation symptoms + overheated. I was lucky enough to have access to an o2 sensor that day, and thats how we ended up finding out what it was.

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That's the best way to sort out this kind of crap, go for a drive (or a dyno run) with a wideband A/F meter on it.

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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.

Based on David's advice my float-chamber fuel level might be a touch low, which as he describes would cause fuel starvation at revs. If there's still a problem once I get that sorted out, I'll be looking at the needle.. but I certainly don't have any sort of overheating problem -- this engine is unbelievable, it's got orange rusty sludge for radiator fluid yet currently rarely pokes its head above 70*C.. and during the week of 40+ temps we had in February peaked at 95*C in heavy traffic and loved it.

I do suspect the ADF isn't perfect, but I doubt it's so far off to cause the sort of severe symptoms I'm experiencing.

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Simon

The adventures of an owner builder in the Tallarook Ranges

I just double checked my SU parts book and that shows the float with the metal strip for hs2 and hs4 carby. The plastic float for hs4c and hs6 and hs8.
The needle valves are different part No. There is no cross reference to say that they are interchangable. The float in the pic I have bought replacements thru my contact at Autopro. They were listed in the fuelmiser parts book. These are all I have ever used.
The listing for your eng/carb is definately ADF needle.
so I don't know???????
try a set of twins and have" double trouble"

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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

It only overheated at highway speed as that part of the needle was too lean for nav with the lcb's and 1 3/4" exhaust. It was fine to put around at low throttle/rpm as it didn't start becoming too lean until about 3,000 rpm

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WHEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!

Picked up a new dizzy rotor button from Scott (BALLISTIC) at Minitopia, mate you're a bloody legend Where else will a Mini nut get parts at 9pm on a Sunday night??

I reckon I got valve bounce in second gear pulling out of your driveway!

It's not yet perfect, there's still a flat spot at about 2/3rds throttle around 3k RPM, but it's a million times better than it was this time last week. Another go on the timing strobe and the correct dashpot oil will see it right, I reckon.

HUGE thanks to David Rosenthal, Doc and others for the tips, after fiddling with the float and carb needle position I reckon it's pretty close, but combined with the correct rotor button I can now pull 120km/h easily (and more if I push). Part throttle at speed still farts around a bit, but push to WOT and it goes away

Very happy

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Simon

The adventures of an owner builder in the Tallarook Ranges

Forgot to mention, I took your advice and filed off the raised portion of the needle sleeve, that made a very noticable improvement straight away. Might not bother changing to a fixed needle now...

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Simon

The adventures of an owner builder in the Tallarook Ranges

Very Good News Look forward to further updates once you have sorted the other things.

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http://www.youtube.com/watch?v=nDMkVq1jRGU