View Full Version : TR2/3/3A TR-3B Float Bowls

04-14-2012, 03:28 PM
My TR-3B always seems to lose quite a bit of gas when sitting for a while. I've checked and can't find any gas leaks and don't smell gas in the garage. I know that the gas tank is vented and assume that that could result in the loss of gas over the winter months. However, the gasket on the front float bowl in particular always seems to be a bit wet. I'm probably going to go ahead and change the gasket and see if that helps. Any help would be appreciated.

Also, does anyone know what the bolt size is for the cap nut on the float bowl? It seems 1/2" is too small and 9/16" is a bit too large. I can't believe that it is 17/32"? Also, should there be a washer under the bolt? Thanks.


04-14-2012, 03:53 PM
Those float bowl gaskets never seem to last very long for me; I wind up having to change them every year or two. But unless the tank is very full or the car is pointing downhill, they can't lose very much gas (just what the float bowl holds).

Someone, I forget who offhand, is making uprated replacements. Mark Macy, perhaps? I'm sure someone will be along soon who knows.

All of the nuts on the carbs are not inch sizes, nor metric. IIRC the float bowl cap is 1/4 BSW (Whitworth). If you don't happen to have a set of Whitworth wrenches handy, use an adjustable wrench (aka Crescent wrench).

The bolt for the float bowl is a Whitworth size as well. Might be 5/16 BSW but I'm not certain offhand.

04-14-2012, 04:39 PM
Thank you Randall. I don't have Witworth wrenches but do have a crescent wrench. I always fill the tank up before I park it for the winter. I guess I shouldn't be doing that. Is it a good idea to plug the vent before putting the car away for the winter, assuming one remembers to remove the plug in the spring?


04-14-2012, 04:55 PM
Given what they are saying about oxygenated fuel these days, it might be better to empty the tank for the winter then start with fresh fuel in the spring. But I wouldn't know, as I drive my TR year-round.

I also have the original tank vent permanently blocked, since it can dump fuel on the ground in hard turns with a full tank. There is a small hole in the inner cap that seems to pass enough air to vent the tank: