View Full Version : TR2/3/3A Rebuilding H4 carbs

01-16-2019, 07:38 PM
I am rebuilding the carbs on my TR-2, under restoration. What ever oil was in the damper res. was apparently to heavy. I could, with a bit of effort push the pistons upward, one even seem to stop, as if it were hitting something? Thought I would clean them out and put some fresh oil in the damper res. What weigh would you guys recommend, and how much to pore in?


01-16-2019, 07:49 PM
Probably varies, but straight 20 weight engine oil seemed to work the best for me. The book says to use the same straight weight as recommended for the engine (chart in the owner's manual).

Look inside for the top of the sliding shaft, and fill to about that level. Any excess will fairly quickly run out and in the process, lube the shaft.

Also check that they move absolutely freely with the plunger out. Sounds like you might have some damage to a dome or something. They are thin and very soft, easy to damage in the parts bin.

01-16-2019, 08:01 PM
Have you already done the rebuild? Or is this just getting a feel before you get started?

01-16-2019, 08:02 PM
Back in the 50s the manuals for cars with SUs said same oil that was in the oil was appropiate. Over the years and improvements to tuning, etc., the oil of choice is 20W or buy the bottle of SU Carb oil (more expensive).

01-16-2019, 08:10 PM
... said same oil that was in the oil ...

This is very deep!?!

01-16-2019, 08:11 PM
(sorry...I couldn't resist...no offense intended as I do the same all the time!)

01-16-2019, 08:33 PM
Pretty deep! My Dad bought a 57 Jag 140 coupe in 65. He was a mechanic thru school. He was amazed they had oil for the dampers and was really in awe with the manual stating engine oil. He was using 20W50 at the time. Car ran good, I learned on it and raced it. My 120 was the same and my MK1 shows SU oil or 20W and it is a 58. My 57 says, same as engine oil. I used 20W in Spits and GT6, late 60s to mid 70s, same as 73 XJ6. Any rebuilds now I use the SU oil as people would rather set a small bottle with spout on shelf instead of a can.

STeve 1958
01-16-2019, 08:45 PM
I use 20w50 and it works great. People who race these cars often put heavier oil in to richen the mixture on acceleration. That hurts the gas milage though. Thinner oil will increase you gas milage but cost you in power. I don't know anyone who owns a TR for the gas mileage so go with the 20 weight.

01-16-2019, 08:52 PM