View Full Version : TR4/4A hsu6 float chamber tr4a

grant tr4a
02-11-2014, 06:00 PM
Hi, I want to open upthe float chamber. I just want to clean out whatever has accumulated. The carbs run fine, but the car sat for most of 5 years before I got it and I have had it for 6 years. What do I need to know before I pull the float tops off. I have new gaskets on the way. Grant

02-11-2014, 08:57 PM
Sounds like you've got it covered. The gaskets can sometimes be reused, but may tear when you pull the lid off. In a pinch, you can run without them, though.

To clean the bowls out thoroughly, though, you'll probably want to take them off. Crud can also accumulate in the line to the jet. As I recall, you can undo the choke linkage to the jet and just pull the jet out of the carb, leaving it attached to the bowl by the little hose.

02-12-2014, 02:42 AM
Once inside of the float bowl you are likely to find that most all of the dirt is settled in the two pockets that are on each side of the well that the hose is connected to. It was designed to trap the dirt in those spaces instead of going through the hose into the jet. You should be able to clean those spaces out without removing the bowl from the carb body. You will need some tool to suck out whatever is in the bottom. It is pretty small.

02-12-2014, 07:42 AM
A small squirt of Carb Cleaner and a Q-tip and Bob's your Uncle.

02-12-2014, 08:48 AM
I am going to go one step further and suggest something the manuals warn against.

If you take a pipe cleaner and make SURE there are no sharp burrs on the cut end of its wires, you can spray car cleaner down into the jet (with the suction chamber, and piston/needle removed) to gently clean fuel gum/varnish out of the jet. The flexible tube to the float bowl can often be cleaned by spraying carb cleaner through the jet back into the bowl where you blot it up with paper towels. You may find you need to spray into the flexible tube, then let things soak for a while and try again. The important part is to make sure that if you use the pipe cleaner it has no sharp ends that would cut/damage the inside of the jet. If you clean the jet and flexible tube with the carb on the car you can often get the passages open without disassembly or disturbing the mixture settings. That will help you with the initial restart of the engine after which you may find adjusting the mixture is necessary.

02-12-2014, 01:59 PM
Another thought-if you remove the jet tube from the float chamber, the seal will often leak on re-assembly. I have found that a 008 o ring make a good substitute and is locally available. Faster and cheaper than having to order one.

02-12-2014, 07:32 PM
While a regular o-ring will seal for a while, its round cross-section will not seal as well as the rectangular section of the factory seal. If you use an o-ring as a temporary fix, either buy the right part or make your own.

The seal can be made from 3/16" low pressure fuel hose. Buy a minimal amount (probably a foot). Use a razor blade to slice off a 1/8" thick donut with parallel sides. Carefully split the outer jacket of the donut and peel it off, down to the fiber braid, then pick off the threads of the braid. The inner donut you are left with will have the same dimensions as the factory seal.

02-12-2014, 08:18 PM
The o ring has been in place for at least 2 years. It seems to compress enough to provide a seal. I will keep the fuel line in mind as it is probably closer to the hardness of the original seal. I might be wrong, but I don't think the seals are available from the "big 3". Joe Curto or Burlen might be the only source.

02-13-2014, 08:48 PM
The Burlen/SU float bowl to jet tube seal is not readily available. The SU part number is AUD2194 and it is supposed to be common to all HS carbs.

AUD2194 is available from Spitbits, Mini Mania and Seven Enterprises. I don't know if other British car vendors in the U.S. have the part.