Hi, I'm setting up my SU,s and have used a depth gauge to set the jet depth at 65 thou as seemingly I read this somewhere. I thought that if jet depth was so critical then how about needle length . So I measured these. The amount protruding from the base of the piston varies by about 29 thou across all three.
I could spend time equalising this but will it be worth the effort?
Any advise or thoughts welcome.
Tim
How long are your needles ?
#2
Tim
There are several excellent SU instructions in the Forum Knowledge Base>Manuals, Technical Guides; I particularly like the period SU Tuning Guide.
There are several excellent SU instructions in the Forum Knowledge Base>Manuals, Technical Guides; I particularly like the period SU Tuning Guide.
David Jones
S1 OTS OSB; S1 FHC ODB
1997 Porsche 911 Guards Red
Add your E-Type to our World Map: http://forum.etypeuk.com/viewtopic.php?f=1&t=1810
S1 OTS OSB; S1 FHC ODB
1997 Porsche 911 Guards Red
Add your E-Type to our World Map: http://forum.etypeuk.com/viewtopic.php?f=1&t=1810
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#3
It is absolutely vital that the needles are set correctly. The shoulder of the needle should be exactly flush with the base of the piston
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#4
I recall that the needle diameters are measured from the shoulder not the pointed tip of the needle, so you should set all 3 with the shoulder flush.
Nick
Nick
1E20498 1965 S1 FHC
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#5
All, thanks for your replies. The older needles did indeed have a shoulder which made things easier but the later ones have a groove. Thus the question is:
To the centre of the groove or the edge. We are only talking thousandths so it may not be critical?
To the centre of the groove or the edge. We are only talking thousandths so it may not be critical?
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#6
Tim,
The lower edge of the groove should be flush with the base of the piston (from Jaguar service manual). You need to equip yourself with some books !
:)
Nick
The lower edge of the groove should be flush with the base of the piston (from Jaguar service manual). You need to equip yourself with some books !
:)
Nick
1E20498 1965 S1 FHC
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#7
Nick, I have loads of books but this later needle didn't feature in any of them. However to complete my education and add to my resource library I have purchased (and it's been delivered today) the SU carburettor manual.
As you say it references to the lower edge of the groove.
As you say it references to the lower edge of the groove.
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