Static Timing BTDC for 1979 Mini 850
Discussion
Try http://www.minimania.com/Article_Type.cfm?DisplayT... A lot of info on timing. Minimania have been around for a long time but I have never tryed there tips befor.
Hope this helps Dan
Hope this helps Dan
The original BMC workshop manuel lists an 850 as TDC for a car fitted with what they call the 'Premium Fuel Distributor' and 7 deg BTDC for the 'Commercial Fuel Distributor.Personally I usually use 5 deg BTDC as an initial setting for an 850, then advance it up a bit once it's running, avoiding any 'pinking' until it feels right and picks up nicely.
guru_1071 said:
lund
i would say it depends on what advance is on the weights inside the dizzy.
you will be aiming for, say, about 28-30 total with a mini 1000 (i think, im more used to 1071's)
so 28 - (aw x 2) = static
so if the advance weight is 10 you will be looking at a static of 8
hope this helps
Sorry to bring this back up after so long, but I still just don't understand. i would say it depends on what advance is on the weights inside the dizzy.
you will be aiming for, say, about 28-30 total with a mini 1000 (i think, im more used to 1071's)
so 28 - (aw x 2) = static
so if the advance weight is 10 you will be looking at a static of 8
hope this helps
28-30 what? degrees circumference that the distributer is turned from points closed, turned clockwise?
How do I know what my advance weight is...whats advance weight!?
Sorry to sound a numpty...
if you look inside the dizzy under where the points go you will see the bob weights. stamped on one bob weight will be a number
write this number down and reassemble and fit the dizzy.
then take your TOTAL advance figure (probably 28 - 30 degrees on a thou) double the number from the bob weight, for example 10, so 10 x 2 = 20. minus 20 from 28 = 8, which is what the static timing would need to be to ideally allow your car to start ok, run without pinking, and stop without running on. with tuned cars running higher cr's you need to find dizzys with bob weights with higer numbers, or mod them (which is complicated).
years ago i had a troublesome 1293 that ran on like a pig. if i moved the dizzy to stop it running on its wouldnt start, backed it up to start, it would run hot and run on. i finally fixed it with the holy grail of bob weights - a monster 16 from god knows wheres, but 16 x 2 = 32, minused from 34 total (a 1275) = 2 degrees of static, which solved it.
you then need to start experimenting with different poundage bob springs to affect how the advance curve occurs, but this is a lot more suck it and see.
its stuff like this that turns minis from pains into decent cars
write this number down and reassemble and fit the dizzy.
then take your TOTAL advance figure (probably 28 - 30 degrees on a thou) double the number from the bob weight, for example 10, so 10 x 2 = 20. minus 20 from 28 = 8, which is what the static timing would need to be to ideally allow your car to start ok, run without pinking, and stop without running on. with tuned cars running higher cr's you need to find dizzys with bob weights with higer numbers, or mod them (which is complicated).
years ago i had a troublesome 1293 that ran on like a pig. if i moved the dizzy to stop it running on its wouldnt start, backed it up to start, it would run hot and run on. i finally fixed it with the holy grail of bob weights - a monster 16 from god knows wheres, but 16 x 2 = 32, minused from 34 total (a 1275) = 2 degrees of static, which solved it.
you then need to start experimenting with different poundage bob springs to affect how the advance curve occurs, but this is a lot more suck it and see.
its stuff like this that turns minis from pains into decent cars
guru_1071 said:
if you look inside the dizzy under where the points go you will see the bob weights. stamped on one bob weight will be a number
write this number down and reassemble and fit the dizzy.
then take your TOTAL advance figure (probably 28 - 30 degrees on a thou) double the number from the bob weight, for example 10, so 10 x 2 = 20. minus 20 from 28 = 8, which is what the static timing would need to be to ideally allow your car to start ok, run without pinking, and stop without running on. with tuned cars running higher cr's you need to find dizzys with bob weights with higer numbers, or mod them (which is complicated).
years ago i had a troublesome 1293 that ran on like a pig. if i moved the dizzy to stop it running on its wouldnt start, backed it up to start, it would run hot and run on. i finally fixed it with the holy grail of bob weights - a monster 16 from god knows wheres, but 16 x 2 = 32, minused from 34 total (a 1275) = 2 degrees of static, which solved it.
you then need to start experimenting with different poundage bob springs to affect how the advance curve occurs, but this is a lot more suck it and see.
its stuff like this that turns minis from pains into decent cars
Im with you now! I will have a look one day when I've got nowt better to do. Right now if I remember correctly its at 7degs BTDC. I static timed the dizzy to a point where the points closed and then advanced the dizzy turning it clockwise a tad. Is this correct to do so, or have i just mucked up my timing? write this number down and reassemble and fit the dizzy.
then take your TOTAL advance figure (probably 28 - 30 degrees on a thou) double the number from the bob weight, for example 10, so 10 x 2 = 20. minus 20 from 28 = 8, which is what the static timing would need to be to ideally allow your car to start ok, run without pinking, and stop without running on. with tuned cars running higher cr's you need to find dizzys with bob weights with higer numbers, or mod them (which is complicated).
years ago i had a troublesome 1293 that ran on like a pig. if i moved the dizzy to stop it running on its wouldnt start, backed it up to start, it would run hot and run on. i finally fixed it with the holy grail of bob weights - a monster 16 from god knows wheres, but 16 x 2 = 32, minused from 34 total (a 1275) = 2 degrees of static, which solved it.
you then need to start experimenting with different poundage bob springs to affect how the advance curve occurs, but this is a lot more suck it and see.
its stuff like this that turns minis from pains into decent cars
Thanks for the great explanation. I guess we're assuming my total advance is 28. How do i find out my total advance weight figure?
Tom
guru_1071 said:
14 sounds more like a 1275 dizzy, as 14 x 2 = 28 which doesnt leave a lot of static (a 1275 would be circa 32ish, in which case 32 - 28 = 4 static)
4 is odd, as 4 x 2 = 8 - 28 = 20 which is far too much static to start with.
This is mad! I checked with the Haynes and I definately have the correct serial number distributer. I also read, post 1976 must be strobe timed as static figures are not given... But I need to be right on the fly first before its strobe timed?!4 is odd, as 4 x 2 = 8 - 28 = 20 which is far too much static to start with.
I know some of the Mk1 850 variants have a static of 19degs BTDC.
What do the A series 998s run? Probs just use the figures from them. I'd like to get it right for my engine tho...
Definately looks like a 4, but there is a straight score mark before the 4, but goes right to the edge of the weight.
What would happen if I did static time it to 20BTDC?
However maybe 4 is right?
Cooperman said:
The original BMC workshop manuel lists an 850 as TDC for a car fitted with what they call the 'Premium Fuel Distributor'
Edited by Mini_Lund on Saturday 20th September 14:22
A static of 20 deg is way, way too far advanced and you will run the risk of starting with the ignition in 'detonation' as soon as you try to drive it. My advice is to go for about 5 deg static. It will start and run with this and probably run very nicely. Then, when you've set the basic mixture you can get it checked with a strobe.
Get it ticking over smoothly, drive it, add a bit more advance and go from there if you want to. However, don't run in detonation - see other post by Skyedriver to see what happens to the pistons if you do!
Get it ticking over smoothly, drive it, add a bit more advance and go from there if you want to. However, don't run in detonation - see other post by Skyedriver to see what happens to the pistons if you do!
Cooperman said:
A static of 20 deg is way, way too far advanced and you will run the risk of starting with the ignition in 'detonation' as soon as you try to drive it. My advice is to go for about 5 deg static. It will start and run with this and probably run very nicely. Then, when you've set the basic mixture you can get it checked with a strobe.
Get it ticking over smoothly, drive it, add a bit more advance and go from there if you want to. However, don't run in detonation - see other post by Skyedriver to see what happens to the pistons if you do!
Its exactly at TDC now...hmmm, should I drive it or not bother until I put 5 degs advance on? Used a lamp earthed to the block and live to ignition to find the timing on the dizzy. Its spot on..Get it ticking over smoothly, drive it, add a bit more advance and go from there if you want to. However, don't run in detonation - see other post by Skyedriver to see what happens to the pistons if you do!
Try it at TDC. It can't do any harm as it's going to be either right or a bit retadrded. Then just slacken off the clamp bolt and, with it ticking over, just wind a tiny bit of advance on. If you hold a cam protractor above the dizzy as you do this you can estimate 4 or 5 degrees near enough. Mini timing, except on competition engines, is fairly tolerant unless you move into detonation at high throttle openings and low to medium revs under load. Just see what's best. Make sure it is not running too weak, though.
Cooperman said:
Try it at TDC. It can't do any harm as it's going to be either right or a bit retadrded. Then just slacken off the clamp bolt and, with it ticking over, just wind a tiny bit of advance on. If you hold a cam protractor above the dizzy as you do this you can estimate 4 or 5 degrees near enough. Mini timing, except on competition engines, is fairly tolerant unless you move into detonation at high throttle openings and low to medium revs under load. Just see what's best. Make sure it is not running too weak, though.
I don't notice any difference between TDC and 8degs BTDC? Still virtually the same.Gassing Station | Classic Minis | Top of Page | What's New | My Stuff