Dashpot

Post by **martylemoo** » Mon Jun 07, 2004 10:51 pm

Hi,
I want to change the oil in my dashpot for a lighter fluid. What is the best way to remove the existing oil? and how much oil should i fill it back up with?
thanks
Martyn

Post by **Cam** » Mon Jun 07, 2004 11:04 pm

Take the dashpot off (3 screws) and withdraw the piston from the carb body and leave it upside-down to drain. Careful you don't damage the needle though as you take it out and put it back!

Post by **rayofleamington** » Tue Jun 08, 2004 12:30 am

I want to change the oil in my dashpot for a lighter fluid.

Wouldn't that be dangerous? If you want to light your cigarrette whilst checking the oil and water, an zippo is probably better

Post by **Chris Morley** » Tue Jun 08, 2004 12:37 am

Yes, very good Ray....

Martylemoo; 'I want to change the oil in my dashpot'.

Any reason why? Did you have problems last Winter when it was cold?

Post by **Kevin** » Tue Jun 08, 2004 1:48 am

Martyn
What do you want to change it to, lots of us just use good old 20w50

Post by **Chris Morley** » Tue Jun 08, 2004 2:08 am

I used to use 3-in-1 oil as recommended by a 'top tips' Minor article, but for the last few years I've used 20W/50. I've had no starting problems, even at temperatures as low as -5 degrees Centigrade. The reason for using a light oil was to ease low temperature starting. I guess 20SAE is fine in the South of England.

Post by **rayofleamington** » Tue Jun 08, 2004 9:28 am

20/50 should be ok - The whole point of a multigrade is that it doesn't go as thick when cold and doesn't go to thin when hot.
Therefore a 20/50 should behavelike an SAE 20 in cold weather, (but is probably better when hot, ie. it still damps the throttle slide)

I use engine oil in the dashpot (Castrol 15/40) and I find it too thin as the throttle slide still opens quickly and for more comfort in a traffick jam, I'd prefer it to be slower.

Post by **martylemoo** » Tue Jun 08, 2004 9:49 pm

just after a quicker opening throttle slide, the 1300 doesnt seem quite as responsive as i want and just something i thought i might try as i do not often drive in traffic.!! cheers guys

Post by **A65Bill** » Thu Jun 10, 2004 11:29 pm

martylemoo wrote:just after a quicker opening throttle slide, the 1300 doesnt seem quite as responsive as i want

I don't think the dashpot oil is likely to be your problem. The oil just damps the movement of the piston. If you run without oil, under brisk acceleration you will feel & possibly hear the piston fluttering. Too thick an oil will just stop the vacuum lifting the piston. 20/50 is unlikely to overdamp it. I would check that you do not have too strong a damper spring, most do. Also check that the piston rim & the dashpost are squeeky clean (but don't use harsh abrasives). A slightly bent needle or a sticking one on a swing needle carb can dull response, as can a worn needle or jet, the jet particularly on a swing needle carb.

Post by **Cam** » Fri Jun 11, 2004 9:23 am

just after a quicker opening throttle slide, the 1300 doesnt seem quite as responsive as i want

I think Martylemoo is on about the 'throttle response' of the engine which IS affected by the oil, as well as the points you mention. Over the years I have tried loads of different oils in the dashpot of carbs attached to mostly tuned A-series engines and I found the best one (for response) to be the oil produced by SU (Burlen) themselves. I tried Penrite dashpot oil, but it's far too thick, as is engine oil (for tuned engines - but fine for standard ones).

Martylemoo, try to get hold of some proper SU dashpot oil from Burlen (I think they still sell it). Give it a whirl and see what you think. It worked OK for me.

Post by **martylemoo** » Fri Jun 11, 2004 9:06 pm

cheers cam,
i will try and get some

Post by **Kevin** » Mon Jun 14, 2004 12:51 am

Yes they do sell it
http://www.burlen.co.uk/