MGB & GT Forum

I have just finished installing new jets on the HS4 carbs of my 68 GT. I have not seen a posting on here (not that I read everything) so I thought I would mention that it isn't a simple unscrew & screw installation. (If this is old news please ignore.) The jets that I used were through Basil and Joe Curto, so I don't know if this is standard design for all manufacturers, as this is the first time I have done this. They looked different from the originals, but similar to those in a Moss video

The biggest difficulty I had was getting a tight seal at the float bowl connection. On my first attempt with the carbs and bowls on the engine was to simply slide the jet into the carb and screw the hose into the bowl. Both leaked when I turned on the fuel pump, lots. I had already checked, on Joe's advice, to be sure there was nothing in the hole left over from the old fittings since, the fitting ends looked different, as seen in the attached pic.

Then I found out the rubber ring, brass washer, and fitting will slide off of the tubing. I started looking for help. Had I damaged them? I found a Utube video from Moss talking about this exact thing. The video shows the ends sliding off and how to install them.

I removed the float bowls to do it on the bench.
The rubber seal ring needs to be at the end of the tube, over the brass inside ferrule.
The coil spring & brass fitting needs to be held back so the tube & rubber seal ring can be pushed all the way into the bottom of the small hole of the bowl port, without the fitting or spring restricting it.
Then the brass fitting can be started and tightened into the threaded hole of the bowl port.
Test to see if the tube is tight by pulling on it. Release the spring.
Now the jet can be slipped over the needle, into the carb, and the bowl can be reattached.

It took some coordination and fiddling to get the tube in while holding the spring & fitting, but that's what was stressed in the Moss video. And it worked. They don't leak and all is right with the carbs.

I should have checked the old rubber jet hoses years ago. They were badly cracked and I'm surprised they had not leaked. The only reason I changed them was the plastic fitting for the lifting arm broke on one of them from old age.

I hope the explanation helps. I didn't take pictures during ass'y because my hands were full, I'm not going the disassemble them just for pictures, now that they are tight.
FWIW