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RE: SU carb tuning, with slight updates.

To: decpa::"british-cars@alliant.com"@dsm.enet.dec.com
Subject: RE: SU carb tuning, with slight updates.
From: mit-eddie!dsm.enet.dec.com!"dsm::holbrook"@EDDIE.MIT.EDU
Date: Mon, 23 Apr 90 06:17:34 PDT
Roger,

I have an update to add to your S.U. tuning proceedure.  As I read the part
about adjusting the float 1/8 in. did not seem right to me.

 
<step 3- Remove the float bowl covers, clean the float bowls, remove old 
<sediment, and check/adjust the float setting. (turn the cover upside down,
<and get a 1/8 in drill bit, set the drill bit accross the cover, the float
<tab should just touch the bit.) Make sure the needle is moving and seating
<properly. This is just like *most* floats. Replace the cover.
 
So I researched a bit and here is what I came up with.

There are 4 basic types of S.U.'s that have been commonly used since the War;
H, HD, HS and HIF.  They have different requirements for the float adjustment.
They are further described by the measurement of the intake port.  The number
designated is the number of eights of an inch over 1 inch.  For example
An HS4 is a type HS with an intake port diameter of 1 4/8 inches.


Type               Description                             Measurment

H     Seperate float bowl attached with one bolt.          7/16
      Jet and choke is exposed.

HD    Jet is not exposed float is held on with 4 screws    7/16

HS    A tube carries fuel from the float.  These have      3/16 (brass)
      Two type of float bowls brass and plastic            1/8  (plastic)

HIF   (IF stands for integral float)  The float is         50/1000 +-10
      adjusted with a straight edge and feeler guage.

Hope this helps.

                                                Dave H.


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