SU H1F 44 dash pot oil

[Garyjohndavies]

Have different oils available for my dash pot -
3 in 1
Straight 20 mineral oil
30 grade motorcycle fork oil
20/50 engine oil .

Which would be the best route ?

Gary

[Murrayminor]

I have used 3 in 1 oil and never had any issues, other oils may be too viscous.

Try this for the recommended item which states its straight 20 oil.

https://sucarb.co.uk/technical-carburet ... hamber-oil

[Garyjohndavies]

Thanks for that .

Gary

[myoldjalopy]

A lot of people tend to use either 3-in-1 or engine oil, apparently successfully. I myself used to use 3-in-1 for decades without problems but, on a whim, did buy the SU oil mentioned by 'Murrayminor' and have been using it happily for the last 5 years or so. Can't say I noticed any appreciable difference with it though compared to 3-in-1.........

[philthehill]

You can use whatever oil you want in the dashpot. The oil used generally is 20/50 grade. I have even used EP 90 to control the dashpot movement.
There is absolutely no need to use the special SU carb oil.

[jagnut66]

Alternatively, this is available (link below).
Best wishes,
Mike.

https://www.morrisminor.org.uk/parts/12 ... arburettor

[philthehill]

Why spend money when a couple of squirts from the oil can is all you need.

[liammonty]

The grade of oil used determines how fast the piston rises under initial acceleration, thus affecting the mixture during this short period. This provides the same end result as an accelerator pump on a fixed jet carb, i.e. richening the mixture briefly, but instead of needing to adjust linkages and needles, you just use a different grade of oil in the dashpot. A thicker oil leads to greater resistance and the piston taking longer to rise, initially allowing less air into the carb and thus giving a richer mixture during initial acceleration. A thinner oil allows the piston to rise faster. I would use a thinner oil as preference, and switch to a thicker one if needed - i.e. if the engine showed signs of hesitation under acceleration, for example, due to the mixture leaning out too much when you 'boot it'. I believe the SU oil is pretty thin. In all honesty, a standard engine will likely run fine with anything remotely oily in it, though

[noidea]

sorry for my ignorance but what is a dash pot how often do you oil it how do you oil it .from the comments i assume its something to do with the carb
my car is an 803cc engine so will i need to oil mine if i dont ask i wont know

thanks dave

[philthehill]

This is the dash pot:-

https://www.ebay.co.uk/itm/Vintage-SU-C ... a629e05f20

You may not have a damper in the dash pot but only a weighted piston as per the link. If that is the case you do not need to put oil in the top of the dash pot. If you have the non weighted damper piston the damper will need topping up say every 1000 miles. Just top up with engine oil - no need for special SU oil. Top up through the top screwed cap. Top up to the top of the piston tube not the dash pot tube.

[noidea]

thanks phil will check mine tomorrow

[dp]

fwiw back in the '80s I tried 20W50 in the dashpot and it killed acceleration so changed back to 3 in 1 and it went back to normal.