22 replies to this topic

[kit352]

It's a 91 998. I use 93 octane in the States. I would say I'm a full 2 degrees back from when I start to hear pinging which seems to be what most recommend. It's also the point where advancing the timing doesn't add to the revs as well.

What is this number on the distributer I should know? First I've heard of it.

[Lplus]

It's a 91 998. I use 93 octane in the States. I would say I'm a full 2 degrees back from when I start to hear pinging which seems to be what most recommend. It's also the point where advancing the timing doesn't add to the revs as well.

What is this number on the distributer I should know? First I've heard of it.

Assuming you have a lucas distributor it should have a 5 figure number stamped on the body of the distributor starting with 4.  If the distributor is in the normal orientation it should be visible by looking down the front of the block.  My Haynes manual states that the distributor for a 998 mini from '82 onwards should be a 59D4 type with the number 41882 and the timing at 1500rpm non vac should be 6 to 8 deg btdc for a high compression engine or 8 to 10 deg for a low compression engine.  Presumably you mean US 93 octane which is the equivalent of 98 - 99 octane UK

As to the idle revs being at peak with the timing as you have set it, that doesn't mean that the timing is optimal at higher revs. The distributor curve is at best a compromise, given that it is defined by two springs and an end stop.

[kit352]

I will have to have a look at my dizzy later to see if I can spot the numbers. To my knowledge it should be the factory one.

[timmy850]

The 5 digit number will only tell you the advance it had when the distributor was new. As they age and wear the springs relax and the curve won't necessarily be the same as it was new. Also the fuel is different so the old curve may not be appropriate anyway. 

 

If you're in the States you can try contacting Darren Haines as he does mini distributor recurving 

https://www.youtube....restorations991

 

But as mentioned above, check the timing mark is correct by taking out plug #1 and making sure the piston is at the top when the timing marks are lined up

Check idle timing, check again at 2000, 3000, 4000, 5000rpm (with the vacuum disconnected)

 

It's quite possible the springs are relaxed and instead of it advancing:

8 degrees at idle to 30 degrees at 4000rpm

Perhaps with a weakened spring it'd be idling well into the curve at 15 degrees idle and getting to 30 degrees at 4000rpm (which would explain why the idle timing is high and performance is overall OK)

[68+86auto]

I don't believe the distributor is your only issue but if you do need a distributor rebuild, Jeff Schlemmer (https://www.advanceddistributors.com/) is who you could see. He can probably help with diagnostics too. What area are you in?

Edited by 68+86auto, 19 September 2024 - 10:58 AM.

[kit352]

I'm in New England.
The weak springs sounds like a possibility. The car has 100k miles on it and while I have records of the rebuild I don't see anything about the dizzy being touched.

[68+86auto]

I'm in New England.
The weak springs sounds like a possibility. The car has 100k miles on it and while I have records of the rebuild I don't see anything about the dizzy being touched.

That's quite typical. Most people ignore the distributor despite it being very important. It should always be checked before the fuel system but most just ignore it.

There's a couple of places in the USA who rebuild Lucas distributors such as Jeff. Alternatively you can probably find someone closer who can check it on a distributor machine. Unfortunately I don't know of anyone around your area but there will be someone.

Before doing anything, I'd test what it's doing at the higher RPMs. Also verify that the vacuum advance is functional.

[kit352]

Vacuum advance is working. It runs like poo if I don't connect it up.
I will check the higher rpm timing when I get near the car again.