the jet sizes are diff from the manual becuse the later solexes had a
smaller chokes 34 vs 37 mm of the older ones that came on the 67 2000
Mike Kerr
Roadster Restoration
3730 Todrob LN.
Placerville CA. 95667
Ph.# 530-644-6777
Fax# 530-644-7252
E-mail: mikekerr@innercite.com
Web page : http://www.innercite.com/~wolfgang
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-----Original Message-----
From: Todd Osborn <trosborn@california.com>
To: Roadster List <datsun-roadsters@autox.team.net>
Date: Saturday, May 29, 1999 3:34 PM
Subject: Re: Solex Jets (long)
>**Caution I have no experience tuning Solex carbs nor do I have a
>running Solex engine at this time**
>Ken,
>Your question is of interest to me since I just obtained a restorable 68
>2000 with a spare Solex engine. Since I have not seen a response, I
>thought I would add some information to a least fan the flames ;)
>
>Solex carbs appear to use the same jet size designation as Webers, the
>jet number refer to the jet hole diameter. For example Jet number 160
>has a 1.60 mm diameter hole. In general terms for gas jets the higher
>number is richer, for air jets the higher number is leaner.
>
>ken pletcher wrote:
>> ...
>> Second question is about solex jets.
>> for idle is the higher number richer or leaner<
>
>I'm unsure here since the idle (pilot) jet meters gas and air -- the
>number appears to refer to the gas jet diameter so a larger number would
>be richer. Mine are #55 (.55mm) and the holes in the side and top (air
>bleed) are >.55mm (~1mm). Note the pilot jet also meter fuel for
>mid-range response (transistion from idle to main jets), if the car
>stumbles off idle one might go to larger pilot jet for mid-range
>enrichment and use the idle mixture screw to lean out the idle if
>necessary. However, the emulsion tubes also affect mid-range so a change
>may be in order there as well. BTW, Weber uses a combined designation
>for idle jets like 55F9, where 55 refers to the gas jet diameter and F9
>is an air bleed code that defies logic (from rich to lean:
>F6,F12,F9,F8,F11,F14,F13,F2,F4,F5,F7,F1,F3).
>
>> for main fuel is the higher number richer or leaner<
>
>The main fuel jet is in the bottom of the fuel block and the larger
>number is richer. This appears to be confirmed in the Factory parts
>listing:
> Part# Part Name
> 16033-25520 Jet-Main #160 -- stock jet size?
> 16034-25520 Jet-Main #155 (1000M) -- leaner jet for high altitude
>(~3200ft)?
> 16034-25521 Jet-Main #150 (2000M to 3000M) -- leaner for higher
>altitude (~6500-9750ft)?
> 16033-25522 Jet-Main #145 (4000M) -- leaner for runs up Mt Fuji
>(~13000ft)?
>
>> for main air is the higher number richer or leaner<
>
>Using the logic above and the Weber convention the higher numbers are
>leaner. According to A. Graham Bell's book "Four-stroke Performance
>Tuning" (refering to Webers) a larger air bleed leans the mixture more
>at high rpm than at lower rpm. A change in main fuel jet size affects
>the mixture strength uniformly at both high and low rpm (remember you
>need to be near WOT to get the main jets going at low rpm). BTW, Bell's
>book (ISBN 1859604358) is an excellent source that covers a wide range
>of engine mods for performance tuning. Bell resides in Maitland, New
>South Wales -- any of Australian Sports owners heard of him?
>
>I disassembled one of my Solexes and noted all the jet sizes; they
>appear to be different from stock. Can anyone confirm the best jets for
>street? These carbs were on a U20 with a Solex ("B") cam and 1.5" OD
>header (I assume stock pistons and compression ratio -- but I haven't
>pulled the head to confirm). Here is a jet listing with the Factory
>Manual and Parts list for reference:
>
>Jet My # Shop Manual # Parts List #
>---- ----- ----------- -----------
>Main Gas #135 #180 #160
>Main Air #140 not listed not defined
>Pilot (idle) #55 #60 #60 (#55 optional)
>Starter #160 not listed not defined
>Accel pump #35 .3mm (#30?) not defined
>Fuel Block #8 not listed not defined
>Emulsion tube #M not listed not defined
>(inside fuel block)
>
>Also my carbs have 34mm chokes (venturis) where the shop manual lists
>37mm as standard. 34mm seems better suited for the street (this is what
>Bell recommends for a 4 cylinder with 500cc per cylinder) and may
>explain the leaner jet selection on my carbs. I wish I had these install
>and running on my car to verify the performance -- I hope to prior to
>Shasta.
>
>Does anyone have a list (and source)of Solex jets available.
>
>If you have read this far, thanks for your time -- I hope someone holds
>the decoder ring.
>
>Todd Osborn
>68 2000 DATSFUN (SU, B cam, Comp springs...)
>68 2000 Solex (low chassis# but in many pieces)
>San Jose, CA
>
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