G'day guys

I often get asked "how do I identify what SU carby I have"? Here's a quick guide.

All SUs originally had tags on the float bowl to identify the make and model of car they were fitted to. For example, HS2 (1¼") carbies were fitted to 1098cc Sprites and Midgets, 1275cc Sprites and Midgets, 998cc Mini, 1098cc Mini, plus perhaps 20 or 30 (or more) different cars. They were all HS2, but the fuel metering needles were different and the float bowl sat at different angles. When fitted in pairs, some were Front and some Rear, some Left and some Right (for east/west engines). H series carbies had a number of different size float bowls. The tags identified all of those variances.

None of which you really need to know. Any HS2 carby can be adapted to suit any of the cars, as it's only the metering needle and float bowl angle that's different.

So what you really need to know is:
1) is it an H series, an HS series or an HIF series carby; and
2) what's the inlet port or throat diameter.

H series
There's a banjo bolt that passes through a "leg" on the bottom of the float bowl and into the bottom of the carby body. The fuel flows through the leg and the banjo bolt, into the main jet.

HS series (S = Side mounted float bowl)
The float bowl is bolted to the side of the carby body, and the fuel flows through a flexible tube from the float bowl to the carby. The flexible tube is part of the main jet.

HIF series (IF = Integral Float bowl)
The float bowl is underneath the carby and an integral part of the main body of the carby. You will only find these in 1½" or larger carbies.

The number after the H or HS tells you the size of the throat, as measured at the air filter mounting face. It's the number of 1/8ths of an inch larger than 1 inch.

So if we talk H series:
H1 = 1" plus 1 x 1/8"
H2 = 1" plus 2 x 1/8" = 1¼"
H3 doesn't exist
H4 = 1" plus 4 x 1/8" = 1½"
H5 doesn't exist
H6 = 1" plus 6 x 1/8" = 1¾"

Same with HS series and with most HIF.

However some HIF carbies were also given metric numbers. An HIF44 obviously isn't 44 x 1/8", it's 44mm inlet port, or a poofteenth smaller than an HIF6.

hope that helps, and avagoodday