[Healeys] HS4 carb jet head and spitting

[Alan Seigrist]

  John -

You have to do all the presets for the floats, jet levels and Idle screws
first before tuning (also all the spark plugs etc.).  Failing to do so
means you'll get tuning over-compensation from one carb to others through
the balance tube, and the carbs will falsely appear balanced when tuning,
when in fact one carb will be running too far rich to compensate for others
running too lean at idle.

Once all the presets are done per manual, especially the jet presets level,
then you set idle speed as slow as possible then adjust richness for all
three carbs in unison until roughly correct, lower idle speed a bit more,
then adjust further, in unison as much as possible, then adjust each carb
individually once the general setting is approximated.  If you do this
right, the individual final richness setting for each carb will then
be only within about a turn and a half of the setting nut from each other.

Of course as you are adjusting, make sure your linkages are delinked during
the process.

Best,

Alan


>> 2013/6/7 john spaur <jmsdarch at sbcglobal.net>
>>
>>  I have questions concerning a BT7 tricarb.
>>>
>>> While tuning the car, it was noticed the two rear jet heads were at about
>>> the same level but the front jet head was considerably higher (all were
>>> below the bottom of the Venturi). It is my understanding the height of
>>> the
>>> seat is related to float height setting and lean/rich jet adjustment.
>>>
>>> Should I recheck the float levels to see if something is amiss and adjust
>>> so the jet bearing seats are more uniform before I tune the carbs?
>>>
>>> The carbs sometimes spit petrol, while cold (common issue I believe) and
>>> upon acceleration when the engine is hot. Is this an issue related to
>>> valve
>>> timing and/or rocker clearance? I think spitting back fuel can be caused
>>> by
>>> a too lean condition.
>>>
>>> Could the valves be staying open too long? I have a Denis Welch road cam
>>> which is similar to a BJ8. Per DW, the rocker clearance is set to .015
>>> cold.
>>>
>>> Needing clues to fine tune the healey.
>>>
>>> TIA
>>> John Spaur