16 replies to this topic

[thebullet]

Hi all, I have a 998cc Sprite with a Cooper head and Single HS4 carb.

I had it recently set up on the rollers and when I was at southam they put in what seems to be thinner Dashpot oil, the car is fine but has a flatspot still.

It is now run leaner because the timing has been set up correctly. I wanted to know why it still has this flatspot and had a thought that it could be the thinner dashpot oil that was put in? My car itself has a thicker oil in it.

I think they put 20W 50 oil in it.

Would it give it a flat spot under heavyish acceleration?

And with the cooper head what would the best dashpot oil be? thicker?

Thanks for the help.

Matthew.

[bmcecosse]

I use 3 in 1 - the thinner the better to get the piston to lift and let the air in! May have to set it richer though. It's not hard to try different oils - till you get something you like.

[liirge]

yer i always say, try the oil that makes the engine run the best, personally in my cars i use the engine oil (20w50)

What I will say is DON'T do what a previous owner did, and use lemon juice, I kid you not!

[thebullet]

I use 3 in 1 - the thinner the better to get the piston to lift and let the air in! May have to set it richer though. It's not hard to try different oils - till you get something you like.

Ok thanks, I did think this, but I didn't want to change something after I had spent all that money on getting it tuned! I may put some thicker stuff in it again and see what that does.

Thanks,

Matthew

[thebullet]

yer i always say, try the oil that makes the engine run the best, personally in my cars i use the engine oil (20w50)

What I will say is DON'T do what a previous owner did, and use lemon juice, I kid you not!

Well according to Mini and metro in southam my engine oil is too thick, but it is what the Haynes Manual says to put in it.

Like I said I may try putting thicker stuff in it again that is in the engine, probably help the flatspot a little!

Matthew\

[MRA]

The correct grade of oil for the SU carburettors is a single grade not a multigrade such as 20/50....

SU oil is available if required..

[thebullet]

Ok thanks,

http://www.minispare...ty=pb&pid=37250

By putting something like that in, would I notice much difference to the 20/50 that is in it now!

thanks.

[liirge]

The correct grade of oil for the SU carburettors is a single grade not a multigrade such as 20/50....

SU oil is available if required..

its interesting this, I 100% agree with you..

however as a point using multigrade oil surely acts a bit like a choke? as it will be thicker when the car is cold, thus richening the acceleration mixture, and as it gets warm the oil gets thinner and this weakens the mixture a wee bit.

I've been pondering this novel musing of mine for a while, what do make of that little idea?

[thebullet]

My flat spot seems to go away mostly when it is warm, I was hoping it was going to be the other way round, meaning I need thicker oil back in it.

[J960mayfair]

i use 2 stroke motorcycle engine works a treat

[liirge]

surely you would need thinner oil if it goes away when warm...

[thebullet]

surely you would need thinner oil if it goes away when warm...

That's what i mean haha

Yeah so, maybe I should go straight for this single grade? which isn't thick when cold?

[liirge]

Yeah 3 in 1 is pretty thin and popular on here!

[thebullet]

Thanks for the help. I think I will try the 20w40 that is in the car atm. See what happens! I'm sure it changes as I have a different head on it.

[minotaur]

Thanks for the help. I think I will try the 20w40 that is in the car atm. See what happens! I'm sure it changes as I have a different head on it.

The original oil supplied by SU is SAE20 , 3 in 1 oil is SAE20