Float Chamber on S.U. carbs

After my fuel line woes a couple of days ago, one of my carbs (nearest the bulkhead) was flooding out petrol from the vent outlet. I guessed that I had somehow dislodged a piece of muck/grit which was blocking the float needle. Phoned a friend (not the Paramedic!) who suggested I lightly tap the chamber to dislodge the particle. This did the trick but I am thinking I now have a rogue particle floating around the chamber ready to cause more problems.
I know I have to dismantle the float chamber and clean it out. Can this be done with the carbs in situ by unscrewing the chamber from underneath or do I have to remove the carbs to get at it?
Any help much appreciated, I have a workshop manual & I'm pretty sure these are HIF 4 carbs.
Thanks in advance.

Billy I guess anything is possible, but if you have HIF4s then the float bowl is made into the carb body unlike the HS series carbs and located on the bottom side of the carb body, so you would be working in the blind and upside down, so for that reason I would pull the carb off, it's not that bad of a job, normally you can have the carb off and on the bench in 15 minutes or so.

Yes the float bowl is part of the main body. Looks like I'll have to fetch it off, as long as I don't end up with a jigsaw of springs clips and washers scattered everywhere I'll be ok I think. Never taken one apart before. It's ok to turn the carb upside down once it's out?

Billy Shears Wrote:

I've done it in place but I know what to expect and if you need to adjust floats---well,thats another story. Just take them off and become one with your carbs!

Just remove the four screws holding the bottom plate on, then allow the fuel to drain off and gently lower it out of the way. The float will dangle but the needle and seat will not fall out.

It is not only possible but easily done to replace the float and even the needle and seat with the carb still on the manifold.

Doing this, replacing choke cables and connecting speedo cables are all birds of a feather. Let your fingers be your eyes and it will happen.

Jack

Billy, I just recently had to do this due to a stuck float (flooded the hell out the charcoal canister, BTW). Like Hap says, it looks a lot worse than it really is. You can do the whole job, start to finish, in an hour and change.

One thing to remember is that even after you pull the offending carb, there will still be fuel in the bowl so be ready to spill about a cup of the stuff once you loosen the 4 little screws. After that, it's cake - these things are amazingly simple inside, and once you take a second to look things over you'll "intuit" what's what.

R.

Once the debris has gone through the float valve, it's in there and will fall to the bottom, and stay there. HS carbs in particular have little baffle walls to give the dirt/water a place to stay forever without causing trouble. The bigger concern is where did the crap originate, and is there more? Commonly prevented by good fuel filters, sometimes resulting from bits of disintegrating fuel hose, especially after working on the carbs. One great thing about SU is that the single jet is big, and the needle tends to clean it out as it moves. The only time crap is a problem is if the carb gets a lot of it - clean it out and fix the source.
FRM

If you don't have one - think about adding an in-line disposable fuel filter near the carbs. One you can see thru would be best.