29 replies to this topic

[AEM]

Wow no clearly definitive answer then, as my dear old Dad would have said, "anything will do, but nothing won't"!

[Cooperman]

The correct and definitive answer is 'SU Carburettor Dashpot Oil' as available on-line.

However, it is similar to 3-in-1 and air tool oil, so any of those 3 will do.

20w50 is not the correct oil and in cold weather may cause the dashpots to rise too slowly.

Is that is definitive enough?

[luismx123]

The correct and definitive answer is 'SU Carburettor Dashpot Oil' as available on-line.

However, it is similar to 3-in-1 and air tool oil, so any of those 3 will do.

20w50 is not the correct oil and in cold weather may cause the dashpots to rise too slowly.

Is that is definitive enough?

Sorry to resurect an old thread, but what exactly happens when the dashpot piston rises too slowly? is that the classic "engine bogging" or issues when you hit the accelerator and the engine doesnt rev up?

[nicklouse]

The correct and definitive answer is 'SU Carburettor Dashpot Oil' as available on-line.

However, it is similar to 3-in-1 and air tool oil, so any of those 3 will do.

20w50 is not the correct oil and in cold weather may cause the dashpots to rise too slowly.

Is that is definitive enough?

strange how Rover. BL and BMC say use the engine oil.

[cal844]

The correct and definitive answer is 'SU Carburettor Dashpot Oil' as available on-line.
However, it is similar to 3-in-1 and air tool oil, so any of those 3 will do.
20w50 is not the correct oil and in cold weather may cause the dashpots to rise too slowly.
Is that is definitive enough?

strange how Rover. BL and BMC say use the engine oil.

Strange also that 20/50 is all i ever use in any mini ive run

[imack]

Atf for me as recommended by Peter Baldwin when he set the car up.

[nicklouse]

the thing to remember is this. It does not really matter what you use as long as it is what was used to set up the carb.

 

if Baldwin used ATF then that is what you use.

if Slark used SU oil then that is what you use.

If Boggs used 3 in 1 then that is what you use.

 

BL/Rover/BMC/Leyland say use the Engine oil. so standard car with standard spring and needle then that is what you use.

[nicklouse]

Sorry to resurect an old thread, but what exactly happens when the dashpot piston rises too slowly? is that the classic "engine bogging" or issues when you hit the accelerator and the engine doesnt rev up?

ok two things happen if the piston is slow to rise the size of the fuel opening is smaller than is should be so you are not getting the correct metering of the fuel. BUT as this is the means of enrichening the mixture you may cause the engine to go too rich on acceleration. and if the piston is not reaching full travel you may have an engine that leans off as well.

 

some reading. just not the pages are not straight reading. be careful to read across as needed.

http://sucarb.co.uk/technical/

[luismx123]

 

Sorry to resurect an old thread, but what exactly happens when the dashpot piston rises too slowly? is that the classic "engine bogging" or issues when you hit the accelerator and the engine doesnt rev up?

ok two things happen if the piston is slow to rise the size of the fuel opening is smaller than is should be so you are not getting the correct metering of the fuel. BUT as this is the means of enrichening the mixture you may cause the engine to go too rich on acceleration. and if the piston is not reaching full travel you may have an engine that leans off as well.

 

some reading. just not the pages are not straight reading. be careful to read across as needed.

http://sucarb.co.uk/technical/

 

 

Interesting....I never thought of it in the reverse way with being too lean if the piston raises too quickly... 
Like i posted a while back, I was having problems when I stepped on the throttle (5-10 deg. temperature outside) as the motor would kind of die and choke itself. Wasnt sure for the reason... Always thought it was over fueling. Kind of makes sense that the opening of the damper controlls the "smoothness" of throttle. Id think that removing the damper completely would be better as you get direct feedback from your throttle....
 

[whistler]

3 in 1 oil which according to their website is SAE 20, the same as the oil that SU recommend.

[croc7]

Calver likes 20W fully synthetic for anything other than bone stock because it is stable over the temperature range. I tried Redline 20W, liked the result and still use it. But all engines differ in how much, if at all, they are modified and how the car is driven so try several different oils to settle on what is best for your application.

Edited by croc7, 26 March 2019 - 02:22 AM.

[ACDodd]

I always love this question!

I rebuilt three carbs in the last week.

One needed 10w/40 oil, the second needed 5W30 oil, and the last one needed ATF!


The point is there is no one oil that's suits all, due to wear and tolerances.

That's what tuning is all about!

Ac

[luismx123]

I always love this question!

I rebuilt three carbs in the last week.

One needed 10w/40 oil, the second needed 5W30 oil, and the last one needed ATF!


The point is there is no one oil that's suits all, due to wear and tolerances.

That's what tuning is all about!

Ac

 

How does one go about learning this? What I mean by this is, how do I know im using the wrong/right mixture? Does it have to do with the engine/state of tune, or the desired "feeling" of the car under acceleration, or possibly how the mixture burns (i.e gunson colourtune to see if its burning right)? 
I have no issue going down the to station and picking up 4 different oil types to test, I just dont know what result I should be looking for :/

[BaronVonchesto]

this is one of those posts that can have no winner. The type you use affects your throttle response. BL used 20w50 back in the day, some people insist on using SAE20 oil exclusively, some like ATF (automatic transmission fluid).

 

At the end of the day it depends on your preference based on your engine and driving style. I suggest you try out different oils for a week till you find one you like,

[ACDodd]

http://www.theminifo...e/?fromsearch=1

Read my response here, it explains how the summer works and how to tune it.

Ac