View Full Version : TR2/3/3A TR3a- grose float valves sticking

07-22-2009, 09:08 PM
I wish my first post werent of this type, but my frustration has gone far enough. In any case Hello! Im a proud owner of TR3 driver car. Nothing perfect but fun :smile:

Now on to the troubles... :wink:

I was having issues with an old Grose valve sticking in the float bowl of my TR3A. It was sticking really hard. It has the stock, likely original SU carbs in it with the side bowls.

I purchased two new Grose valves from Moss, one as a spare and replaced it. I noticed they both seemed to stick a bit, but installed the one that felt the loosest. I took the car for a short trip up the hill (incase it dies its easier to coast back home!) and sure enough it stuck again and killed the car. One bowl with a new valve is empty, the other is full. The old grose valve in the other carb is very free and never sticks.

Fuel pressure is about 2.25 psi with a hot engine from an aftermarket electric pump long ago replaced by a previous owner. There is no pressure regulator, just an after market strainer and filter which are both clean. Fuel lines are new, not kinked, and have been purged with cleaner and compressed air. No obstructions in the bowl lids, fuel lines are insulated, and im not vapor locking. The lever on the float bowls have been set to 7/16" per tech instructions.

Suggestions? Should I contact Moss about the parts? Ive been thinking of replacing the fuel pump with something a little higher pressure to force the valve open but i dont want to band aid it.

Thanks for the help guys!


07-22-2009, 09:13 PM
All I can say is that you are not the only one who has had similar problems with the Grose Jets.
I went back to the original plunger type.

Andrew Mace
07-22-2009, 09:28 PM
:iagree: ...what he said! In fairness, I will point out that lots of folks seem happy enough with them!?

Regardless, sounds as if you've plenty of fuel pressure; increasing that likely would cause more problems than it solves!

Geo Hahn
07-23-2009, 10:27 AM
Welcome to the Forum. More than a few of us had our first post be a problem rather than an introduction. Very appropriate I think.

One definition of madness is 'doing the same thing over and over again but expecting a different result', i.e. as noted, a switch to the original style jet should resolve this.

07-23-2009, 12:42 PM
I harvested some original style valves from a spitfire i have parked out back. The car was certainly running better, but it happened again. I checked how much fuel volume the pump was producing, which came out to around 8.5 <span style="font-style: italic">CUPS</span> an hour free flowing. Couple a sticky valve with a general fuel starvation issue, and i think you get my problem. Gonna go get a new pump today i think.

Glad i was able to get on the forum, and am happy to be part of the community :smile:



07-23-2009, 06:40 PM
Renotr3, take them out, flush with carb or brake cleaner. For some reason they come with some kind of sticky grease on them, that it takes gas forever to flush off. Float levels should be spot on. Good luck.


07-23-2009, 09:28 PM
Back a couple of months ago I posted a question to be convinced to order Grose jets and got a mixed review. You ether love them or hate them. Most of the negative comments came after I ordered them and may not have if I hadn't jumped the gun.

I must say so far I love mine. I've had trouble with the red tip valves sticking after they had been installed for a year and this happened twice to me. The best thing I did was took the advice of one of the posters and cleaned them thoroughly with carb cleaner before installing them. I took a can of carb cleaner and sprayed some in the cans cap and let the Grose jet soak in it for a half hour. Then I blow them out with air. Did this process twice. At the bottom of the cap it looked like I was panning for gold because the bottom was covered with brass fillings. The jets are shipped with cosmoline on them and if you directly in stall them right from the bag you will have problems. Gasoline does not dissolve cosmoline it just makes it sticky.

A friend of mine was the service manger for our local Triumph MG dealership and he had told me last week that he had installed Grose jets in hundreds of vehicles over the years and can't remember ever having a problem.

I would remove them and clean them as suggested then reinstall. Don't for get to reset the float fork gaps to 11mm.