[Healeys] SU Carburettors (was: Pre-ignition)

[Austin Healey]

There is an easy test, I always do with multiple SU installations. I put
the dashpots on a table next to eachother, and visualy check if they fall
approximatly the same same speed or not. I  do the test with and without
springs. This is not a "scientific" test (best would be to test the dampers
with vacuum, but I dont have the instrument yet).
With the most precise efforts You always have some difference between the
carbs, one can see it on a rolling road.
The most wierd was a Mini Cooper, which was working flowlessly up to a
given rpm (5500 aprox), where suddenly one carb dashpot fell in and one
went up completely. I changed the dashpot, the carb without success. I
still dont know what it was.

Gergo


2013/6/5 Bob Spidell <bspidell at comcast.net>

> Yup.  Our BN2 had mis-matched dampers, and the carb pistons wouldn't rise
> and fall in sync.  I managed to cobble two with the same characteristics
> together from some spare carbs.
>
> The small, brass 'pistons' on the end vary.  They function as check
> valves, allowing the pistons to fall quickly and rise slower (upward
> movement closes the 'valves,' and downward movement opens them).  They are
> rather intricately cast and/or machined--another testament to the
> sophistication and refinement of SU carbs.
>
> Bob
>
>
> On 6/4/2013 5:54 PM, David Porter wrote:
>
>> For the record: Some SU's are vented internally and some through the cap.
>> Also for the record. Not all dampers are the same, either in rate of flow
>> back or even in diameter. They are not mix and match at your whim. Same
>> goes
>> for the piston springs.
>> Dave
>>
>> frogeye at porterscustom.com
>>
>> Porter Customs   2909 Arno NE
>> Albuquerque, NM USA 87107
>> 505-352-1378
>> 1954 BN2  1959 AN5
>> Porter Custom Bicycles
>>
>> gallery:
>> http://picasaweb.google.com/**porterscustombicycles/**
>> PorterCustomBicyclesStuff<http://picasaweb.google.com/porterscustombicycles/PorterCustomBicyclesStuff>
>>
>> GO HERE: http://porterbikes.com/  nice pictures-fun facts-my world
>>
>>
>>
> --
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> Bob Spidell           San Jose, CA            bspidell at comcast.net
>
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