SU float bowl top

[swifty]

Hi , just building a set of HS4 twin SU carbs . Is there a reason why a particular set has the overflow on some lids and some don’t . I don’t like the potential threat of petrol straight onto the hot exhaust . So can I simply just use lids that don’t have the overflow pipe on them ? …. Shirley

[Peter Laidler]

I don't understand your concern Swifty. HS2's have an overflow that drains straight down onto the manifold. It is a hidden hole, beneath the little alloy tag on the inlet pipe. That said, it will only over flow if you fail to correct the needle valve and float level. If those are correct, then the back loading in the fuel line will stop the flow. Unless you fit a non standard supposedly super-dooper aftermarket pump.

The overflow facility also assists in allowing the fuel to fill the 'sealed' bowl. If there was no escape hole - or overflow facility - there'd be or could be an air lock

Someone please tell me if I"ve got this all arxx about face

[timmy201]

All lids have a vent/overflow hole.

Some lids have one inlet port and one tiny vent hole

IMG_3191.jpg

Some lids have two inlet ports (that you can link two carbs together with)
Some lids have one inlet port and one overflow port

CARB SHOWING LATER TWO PIPE FLOATBOWL LID pic 1.jpg

Some lids have two inlet ports and one overflow port

SU Carb Setup.png

If you want to direct the overflowing fuel away from the exhaust, then you need to get a lid with a port that you can attach a rubber hose on. You direct the hose down to the ground somewhere away from the exhaust

[swifty]

Thanks for reply . Great answers , Pete I’ve never noticed that whole before or just never took any notice of it . …. Shirley

[Peter Laidler]

Never noticed it before........... You would if it had hair round it!!!!!