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TR3 with a Jag HD8 carb SuperCharged

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tinman58

tinman58

Jedi Knight
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Hi Guys
I have a TR3 with a Moss Motors Supercharger. I installed the Supercharger last July. The car ran great until I cracked the crank shaft. I rebuilt the motor with a new crank and went to the 89mm pistons. Everything else stayed the same. I have the engine running but the carb on the S/C is running REALLY RICH. All I did was remove the S/C set it on the bench then reinstalled it as it came off the old engine. I have gone thru all the obvious things and even reset the adjustments as the book says. When I start the car with the choke, gas pours out the throat of the carb. Also into the supercharger. Any thoughts
 
First thing I would look at was dirt, or a dislodged piece of fuel line, in the float valve.
Next, I'd look for a sunk float.

Taking it off, and probably laying it over on it's side, dislodged and garbage resting peacefully in the bottom of the bowl. No telling where it ended up.

Lastly, I'd be looking at the vent....you didn't accidentally plug it, did you?
 
I just found a diagram of the HD8. And I think you are right,that some crud may have gotten between the diaphram and is leaving it open. Will check it tomorrow evening. Thank you for the responce.
 
Took the supercharger off and took apart the valve and the diaphram, all was clean and in good order. What did you mean (plug the vent) there was no vent on the carb, only a piece of fuel line where a vent would go. (it came that way from Moss)
 
The float bowl has to vent somehow.
If the vent is plugged, it will do just that!
Overflow pipe, should be top centre on an HD8, banjo fitting, off to tome side and down. Fuel like comes in the side of the top cover.
That's how yours is?
Dave
 
There is no vent tube like the diagram I found, all there is is i 1/4 inch long piece of gas line where a vent tube should be. I will order a vent tube from Moss today. Thanks for the advice.
 
As long as it's open, it will work. The tube's purpose is to direct any overflow or venting down, away from hot and possibly electrical areas. The hose is clear?
Then that part is okay.

Now, if you are sure the needle, seat and float are okay, not dragging, then what fuel pump pressure do you have?
 
That overflow is supposed to take any excess fuel and divert it overboard. If it's plugged (like, a bolt in the end of the hose, or the end of the hose plugged into something) it will not allow the float valve to close, and it will percolate into the throat.
 
As you can see there was no vent tube as it came from Moss. Again the car ran great when I removed the supercharger. Now it floods out. I took the carb apart and found no dirt or crud at all. I am going to buy the vent from Moss, just because, I will reinstall the supercharger tomorrow and see what happens????

IMG_7714.jpg
 
It's supposed to be where that bolt and tag is. I've never, as in ever, seen an HD8 without a float bowl vent. Maybe it's internally modified to work with a supercharger.
Just remove the bolt, find a nut that fits over it, drill a couple of holes in a couple of the flats, put the vent nut in place, bolt it down, and try it.
Now that I see a picture, I am guessing they sent it out as a replacement, and you were supposed to use your vent tube. Since you didn't have the old one, you had no vent tube to install.
NO idea why it worked before....unless the lid was loose.
 
Dave
Thanks for your input. I will try your idea of drilling the holes in a bolt to see if that does anything. I am a little flustered why it worked fine before and not so much now. But then again it is a british a auto.
 
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