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HarryL
07-18-2014, 05:20 PM
What's everyone's favorite oil for their SU's ?
I've been using some leftover marv's mystery oil.
Before that had some chain saw lube.
Have a good weekend watching F1 !
Harry

Crankshaft
07-18-2014, 05:37 PM
Personally, I use straight 30 wt motoroil.

Geo Hahn
07-18-2014, 06:43 PM
I find MMO (or ATF or such) to be too light weight -- smells nice though. I usually just use whatever I put in the crankcase (20W50).

I am equally non-fussy about what I use for chain saw lube.

karls59tr
07-18-2014, 06:56 PM
What's everyone's favorite oil for their SU's ?
I've been using some leftover marv's mystery oil.
Before that had some chain saw lube.
Have a good weekend watching F1 !
Harry

Extra Virgin Olive Oil.......Sorry couldn't resist.:smile-new: Actually I've been using ATF as it seems to have quicker throttle response than motor oil but maybe it's just me.

TR3driver
07-18-2014, 09:00 PM
I did some experiments years ago with my previous TR3A, and decided that straight 20 weight gave the best throttle response. Any thinner than that produced a bit of a lean bog, while 30 or 40 weight was definitely too thick and made it harder to control the engine smoothly.

But straight 20 weight is hard to find these days, so when I got the current TR3 running, I used 20W50, which worked well enough. Almost no noticeable difference when I eventually found a quart of 20 weight and went back to that.

I actually built a crude "vacuum cleaner" from an old mason jar and a cheap venturi vacuum pump from HF, just to make it easier to try different goops without removing the domes. I also eventually learned that my domes have enough slop in the mounts that just R&Ring the dome can affect jet centering! Gently twisting the dome CCW while snugging down the screws seems to make it more repeatable. (I'm sure CW would work just as well.)

PS, no doubt it depends a lot on where you have the base mixture set. If it is a bit on the rich side, then the accelerator pump effect is less important. Ambient temperature will make a difference too, both because the carbs tend to go rich with hot air and because the oil thins out when it gets hot.

Got_All_4
07-18-2014, 10:09 PM
Try the dollar type stores for 20 weight oil. They seem to have a lot of the odd ball stuff that doesn't sell else ware.

JKB1957
07-18-2014, 10:42 PM
I've used ATF for years without any problems. In fact I'm still using the quart of ATF I bought in 1990.

toysrrus
07-19-2014, 12:43 AM
Hi Folks,

I used to use the Moss (Expensive) blend. When I sold my `57TR3; I gave the bottle away that I had "Forever".

Currently; 20W50. Car runs just fine.

Russ

TR3driver
07-19-2014, 03:44 AM
Try the dollar type stores for 20 weight oil. They seem to have a lot of the odd ball stuff that doesn't sell else ware.
Interesting idea. I'll try one tomorrow.

RJS
07-19-2014, 07:46 AM
Tell me if this is strange. I check my dashpots every season and in 14 yrs and 11K miles I don't recall ever having to top them up. How is that possible?

If dashpot oil has to be periodically replenished, where does it go?

Bob

Geo Hahn
07-19-2014, 08:28 AM
On later cars I think there was a seal (or something) at the bottom that could leak -- but on the SUs I am familiar with there is no place for it to go. So why do some people say they need to keep refilling those?

I suspect it is because they are over-filling the reservoir and the excess gets pulled in (as an upper cylinder lube?). When they look again the level has gone down and they top it up and overfill once again.

TR3driver
07-19-2014, 08:57 AM
Depends on how full you fill them. The earlier TR3 manuals say to, in effect, overfill them slightly every 6000 miles. I believe this is so the excess can slowly run down the center shaft and lubricate where it runs against the dome. But the dampers still work fine with the oil level lower and then there is no place for the oil to go.

For SUs anyway. On most TR6 (and Stags etc) with the emission ZS carbs, there is an O-ring seal inside the dashpot that can leak and allow the oil level to drop.

karls59tr
07-19-2014, 09:09 AM
I did some experiments years ago with my previous TR3A, and decided that straight 20 weight gave the best throttle response. Any thinner than that produced a bit of a lean bog, while 30 or 40 weight was definitely too thick and made it harder to control the engine smoothly.

But straight 20 weight is hard to find these days, so when I got the current TR3 running, I used 20W50, which worked well enough. Almost no noticeable difference when I eventually found a quart of 20 weight and went back to that.

I actually built a crude "vacuum cleaner" from an old mason jar and a cheap venturi vacuum pump from HF, just to make it easier to try different goops without removing the domes. I also eventually learned that my domes have enough slop in the mounts that just R&Ring the dome can affect jet centering! Gently twisting the dome CCW while snugging down the screws seems to make it more repeatable. (I'm sure CW would work just as well.)

PS, no doubt it depends a lot on where you have the base mixture set. If it is a bit on the rich side, then the accelerator pump effect is less important. Ambient temperature will make a difference too, both because the carbs tend to go rich with hot air and because the oil thins out when it gets hot.

In Bob Shaller's More BS about TR's he says to get a flat piece of glass or mirror,lay some fine sandpaper on it ,place the dome on that and gently rub the dome on the sandpaper to level out any height inconsistences. That way the the dome will sit square. And make sure to tighten the screws evenly. :-)

Vila
07-19-2014, 02:01 PM
33973

I use 3 IN ONE Motor Oil. I am not taking about your normal 3 In One multi-purpose oil.

This stuff is a 3 IN ONE product that comes in a blue / white / black can rather than the normal multi-purpose oil that comes in a red / white / black can and it an be found at most hardware stores or on Amazon.

It is SAE 20 weight and is advertised as being for 1/4 HP or larger electric motors.

It comes in the standard 3 IN ONE can with the nozzle that makes it easy to put in the dashpots.

Vila
1933 Chevrolet
1962 Triumph TR4
1984 BMW 633 CSi

TR3driver
07-19-2014, 04:45 PM
In Bob Shaller's More BS about TR's he says to get a flat piece of glass or mirror,lay some fine sandpaper on it ,place the dome on that and gently rub the dome on the sandpaper to level out any height inconsistences. That way the the dome will sit square. And make sure to tighten the screws evenly. :-)
I've done that; but it doesn't address the dome being a loose fit on the body (and screws). I didn't try to measure it, but I'd guesstimate the slop at around .005", which was enough that the jet would drag or not drag. Might just be my carbs, of course, but they both seem about the same.

luke44
07-19-2014, 05:32 PM
On the Spitfire race cars we used to remove the plunger ends altogether and leave the cavities bone dry. For street use any of the above light weight oils are good suggestions.

HarryL
07-19-2014, 06:53 PM
Thanks Everyone.
Have some ATF laying around. Will give it a try.
Enjoy F1 tomorrow.
Harry

6TTR3A
07-19-2014, 10:25 PM
Good old 3 in 1 sells 20 wt in mini cans, easy to store in your wheel well !33982