• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

20w50 in dashpots

Share this page

Woodie

Woodie

Jedi Warrior
Offline
I guess this is to heavy then for dashpots eh ?? Should 3 in 1 or marvel or 10w30 be used ??
 
I believe the original SU oil was 20W. I think 3-in-1 (red and white label) is 30W but the last time I looked, that information was not on the bottle/can. I seem to remember that 3-in-1 also used to sell lube oil for electric motors (blue and white label) and that oil was 20W.

I'm sure others will post regarding running everything from WD-40 to molasses. I have no experience regarding alternative damping oils.
 
20W is fine.
 
When I bought my '79B new, the service manager of the dealership gave me a quart of automatic transmission fluid & told me to use it in my ZS dash pot...that's all I've ever used & the carb's only been apart once & that was after the care had been in storage for 3 years while I was overseas with the Army...auto trans fluid is all I use in any of my carbs.
 
I used ATF when I first got my car but have since switched to 30wt in one car and 20-50 in another. The ATF caused a lean condition on acceleration.

The air flow responds much quicker than the fuel flow when the piston moves. The reason for the oil is to slow the piston movement down so that the air and fuel ratio stays roughly the same. I’m sure Jeff (Bugeye58) will chime in, but I think he runs different weight oil in each carb on the same car. Things wear out on these carbs and as much as I’d like to say that I always fix the problem instead of covering it up that is simply not the case. I can’t justify a complete rebuild on a carb (with good throttle shafts, etc) that just has some piston and dashpot wear causing the piston to rise at different rates. Get the ignition in order, balance the carbs, set the idle and watch the piston travel in relation to each other when giving it throttle. If they match but the car runs lean then you need heavier oil; rich then they need thinner. If one piston moves quicker than the other then the quick one needs heavier oil or the slower needs thinner oil.

Now all that being said, just run what you put in the engine and just go for a drive. It really doesn’t matter./ubbthreads/images/graemlins/driving.gif
 
OH, now that's insight. Of course it makes so much sense when put that way.
 
i use blueberry syrup, that way if i break down i can have a pancake break ; )
or 20w50 works too....think im gonna try 10w30 also and
see what happens.......zzimmmmy
 
now theres a tip you wont find in any book that i have read. well put CrisS.

mark
 
Chris, I'm currently running 20W50 in both carbs on the '72 & the '74.. I run 20W in the '65, and ATF in the '63. I can't remember what I put in the dual 150CD ZS setup on the GT6. Probably whatever was handy at the time. The race engines don't even <u>have</u> dampers in them, as most of the time they're at WOT.
I did, at one time, have a set of carbs that I ran different weight oils in each of the set, due to a worn dashpot assembly.
Whatever works for a given carb will be correct. The only way to find out is experimentation. We've all probably got 10 different oils lying about, and it doesn't take much to figure out what is going to do the trick.
Jeff
 
I've noticed that the ZS does better with auto transmission fluid that SU's - until they're adjusted & then they don't care either....remember, the owner's manual spends much more space on explaining how to fill ZS dampers.
 
I run 20w50 in both my Bugeye and my TR4. I've tried lighter weight stuff in my TR4, but it didn't seem to run as well as with the 20w50.
 
[ QUOTE ]
i use blueberry syrup, that way if i break down i can have a pancake break ; )

[/ QUOTE ]


Blueberry syrup Zimmy? Disgusting!

Maple is the only way to go.
 
I can sell you my secret special blend for only $30/pint. It is guaranteed to improve the performance of your car (by lightening your pockets). It contains genuine snake oil.
/ubbthreads/images/graemlins/wink.gif
 
hehehehe...what type oil in diashpots is an eternal question for which each of us has our own preferences for whatever reason...however, I might just try the maple versus blueberry syrup...hehehehe
 
i tried 10w30 today and suffered from improved response and possibly a little more power.....think ill learn to live with it /ubbthreads/images/graemlins/wink.gif ....zzimmmmy
 
Now, just for the heck of it, zimmy, try auto trans fluid & tell us how it compares to 10W30 in your carbs.
 
Zimmy strikes again.
 
I use ATF as well, in the race carbs I don't use anything I want them bad boys opening as quick as I can get them to. All the oil does is control the lift rate of the pistons, thicker means slower, lighter means quicker, nothing means real quick.
 
Back
Top