Dash pot oil

[arcturus]

I know that the book recommends ATF or similar but what effect would it have on performance using a heavier, engine oil for example, or a lighter oil ?

[Clan]

Originally Posted by arcturus

I know that the book recommends ATF or similar but what effect would it have on performance using a heavier, engine oil for example, or a lighter oil ?

a heavier oil would make the piston rise slower restricting power and increasing fuel consumption .

[classicswede]

Stromberg carbs should use ATF

SU carbs should have SAE20 oil but I find 10w40 works well. Slightly thicker oil will give more enrichment is acceleration, something these engines tend to need.

[arcturus]

Originally Posted by classicswede

Stromberg carbs should use ATF

SU carbs should have SAE20 oil but I find 10w40 works well. Slightly thicker oil will give more enrichment is acceleration, something these engines tend to need.

That was my understanding. Thicker oil slows the rise of the piston under heavy acceleration and momentarily causes a richer mixture.

[CLIVERALLY]

ATF is more stable across a range of temperatures

[amazon69]

ATF is more stable, because it is single weight. Straight SAE20 weight oil is ideal really, in my experience, and as recommended by SU/Burlen: http://sucarb.co.uk/technical-carbur...gs-chamber-oil

I found some single 20w oil for much less however (I think it was for a lawnmower, can't remember).
10w40 etc would change characteristics as the engine warmed up.

[GreenBrick]

Originally Posted by arcturus

That was my understanding. Thicker oil slows the rise of the piston under heavy acceleration and momentarily causes a richer mixture.

I also thought the same, and used engine oil in my twin SUs on my Maxi.

On my stage 1 tuned Mini, I used richer needles and still got it to pass emissions.

[ASt85]

Originally Posted by GreenBrick

I also thought the same, and used engine oil in my twin SUs on my Maxi.

On my stage 1 tuned Mini, I used richer needles and still got it to pass emissions.

Emissions weren't a major factor when I broke my Cooper S up in the summer of 1975, there was far too much to repair in terms of sills/rear subframe/bootfloor, rear floor panel, front inner sills & etc. most of the non-fibreglass panels were riddle with the rot and at the time I had neither the time nor the money to replace the body............sold the engine for more than I'd paid for the car and all the "go faster" parts over the preceding 7 years, which paid for a four year old Ford Corsair V4.

The only car I've driven which even comes close to the handling of that 997S is my son's Japanese grey import '92 Eunos/MX5 - it produces the same grin factor when you start it up and slot it in gear...sadly, (nah ) it is sat on our drive and I am forced to drive it every week or so to stop the brakes sticking/seizing.....the C70 almost does it but can't quite get the hang of this new-fangled thing called aircon in a cabriolet, but then the Eunos also has it - still can't figure out why anyone would need air-con in a ragtop!