View Full Version : TR2/3/3A Uh Oh - will these carbs work on an early TR3

01-16-2016, 07:43 PM
I purchased a set of Joe Curto rebuilt H6 carbs back before Christmas. They were for a TR4 engine in a Morgan. One of my winter projects is to install them on my 56 TR3. Of course the plumbing around the float bowl is different.
First question is what is the nomenclature of the new carbs?
Can they be adapted for my TR3, (change float bowl tops etc)?
Thanks, in advance for any help!

My carbs:
40853 40854

New Carbs:

01-16-2016, 10:14 PM

i think the bowl tops would simply swap out if you wish or just bolt the carbs on and use the later style fuel connections - should work fine unless you want to stay with the older banjo style connections. Those connections you have though have been altered already so I'd vote to bolt on the new ones as is.


01-16-2016, 10:29 PM
I go with Randy, I have HD6 carbs on my TR3 and that required a little change in the linkage, but it works fine.

01-17-2016, 03:21 AM
Should be easy, since you already have the modern fuel line with a clamp. You might need to make up a size adapter, as ISTR the early fittings took 5/16 id line, while the later ones are 1/4"; but that should be easy enough. One way would be to put a "universal" fuel filter in the line, using 5/16" on one side and 1/4" on the other.

For the line between the carbs, I used copper refrigeration tubing to make up a hard line similar to the one on later TR3 and early TR4; but you could make it all soft line.

In case it's not clear, the upper right fitting (in your photo) is the fuel inlet from the pump. The lower right fitting (which is somewhat bent) is the outlet to feed the rear carb. The short fitting to the left of it is the bowl vent.
On the rear carb, the fitting on the right is the fuel inlet (from the front carb), the other fitting is the bowl vent.

The bowl vents originally had short sections of soft line, plus a short length of hard line bent into a 90 degree curve. On the TR, the curved section was turned so the bare end stuck into the air cleaner for that carb.
What I've done instead is to omit the hard line, and use much longer lengths of soft line which hang down to the frame rail. That way, if the float valve does stick open (or get blocked with a piece of crud), the fuel gets dumped on the ground instead of into the air filters and down over the hot exhaust manifold.

This doesn't show much, but maybe it gives some idea

01-17-2016, 04:51 PM
Randy, Jerry, & Randall,
Thanks for the quick and helpful inputs. I think I'll bolt them right on and just reroute the fuel lines using soft and hard tubing. Randall, you answered the $64K question, which inlet/outlet is which. I had also wondered about the float bowl overflows and will add tubing that takes them down and away from the exhaust. It is nice to have some time to do these winter projects and lots of helpers standing by!