21 replies to this topic

[mickthefitter]

Hi. I've just been trying to improve the performance of my Wolseley Hornet a little by altering the timing. Last year my local garage mechanic who MoTs the car, and rebuilt all the brakes for me, said he thought it was holding back a bit. The car does feel a bit reluctant sometimes. I've already read some posts on here about timing advice for using unleaded petrol. I tried checking the dynamic timing using an 80s Gunsons Tachostrobe that i've not used for years, but I found the timing marks indistinct in the mirror I was using, so decided to just drive the car round and tweak the timing using the vernier. My Haynes manual reckons, I'm sure, that 11 'clicks' on the vernier equals 1 degree of timing. I advanced the timing by a maximum of 22 'clicks' before driving the car. At first I thought it was improved but when I put it back as it was I couldn't really tell the difference. I couldn't hear pinking at any time under acceleration. At tickover I advanced, then retarded, the vernier by 50 'clicks' from the datum and could not hear a distinct change to tickover speed. Surely if 11 clicks is 1 degree, 50 should have a large effect on the timing and therefore the tickover speed? Are the verniers on the 25D dizzy known to pack up? Cheers.

[carbon]

Mick,

 

11 clicks on the vernier is 1 degree with the 25D.

 

I have never had problems with the vernier jamming. I have always set up by static timing method, using the timing marks on the flywheel and a multimeter to check exact position when the points open.

[mickthefitter]

Hi thanks. Do you reckon the engine speed should alter though at tickover if I turn the vernier adjuster? I used to find using a strobe light relatively easy on a car like a Morris Marina in the 80s when you could paint a white mark on the crank pulley and the correct timing mark on the block, but I could barely see the marks in the mirror on the transverse A Series. I could give the static method a try using a dwell meter to tell me when the points open, but I'm still not sure how to interperet this 'retard the ignition for unleaded petrol' business. I guess its been done on my car but I think my garage man's feeling was it had been retarded a bit too much.

[KernowCooper]

The marks can be seen but your going to have to invest in a better timing light, I would at idle take a reading of the timing with the vacuum disconnected and see what it is now, and centralise the vernier adjustment, set it to what your engine number dictates and road test the vehicle. Then carry out any adjustments as required, do you run valve master or simular now if the heads not had unleaded inserts?

[mickthefitter]

I use Wynn's Lead Substitute. I don't do a lot of miles. The car has just emerged from winter hibernation and I'm on a 1500 mile annual insurance policy. I read something about centralising the vernier adjuster somewhere either on this forum or in my Haynes manual, but I don't fully understand what is meant by that. Turning my adjuster didn't seem to have a visual effect on the distributor nor any effect on engine idle speed, so I'm not sure what I'm looking for to say it is central. I reckon at one point I could just make out the 5 degree stamp on the flywheel, and looking in the mirror, I think the stamp was on the bulkhead side of the timing pointer, which if I'm right would suggest it is very retarded. I can't remember what rpm that was at though. I tweaked it a bit while playing around. The Haynes book says set at 600rpm which I guess is about the slowest speed a Mini engine will tickover at. But some references on the forum quote higher rpm figures to set the dynamic timing. The Gunsons Tachostrobe has a prism with a shadow in it which is supposed to guide you towards judging what rpm a non-tachometer equipped car was doing, but I always found it a bit difficult to interperet. It was cutting edge technology in 1984!

[KernowCooper]

Centralise the vernier just means the adjustment in in the middle of the threaded section so you have the same advance retard each way. What years your engine and the engine no I'll check what the factory manual says by number.

[mickthefitter]

Right, okay. I'll have to play around with this vernier some more to try to understand it. The only bit of thread I can see is the bit protruding from the bottom of the knurled wheel, and like I said, turning it up to 50 clicks each way seemed to have no effect whatsoever. It does work with the dizzy clamp tight doesn't it? I thought that was the point, so you could tweak the timing without moving the clamp. As far as my engine is concerned, I'll have to get back to you with the number. The log book still has the Wolseley's original engine number in it - it's a '63 car - but in the past someone changed the engine for one starting 99H. I once tried an online resource listing engine numbers to try to find out more about my unit but the resource didn't recognise the whole number. The best it told me was it was a post '71. It uses the original long gear lever but the box is an all-synchro. I'm not sure how they managed that because I thought once the gearboxes went all syncro you got the short remote lever, apart from on the early 70s 850s, but my car is certainly a 998. Tomorrow I'll look under the bonnet and note the engine number. Cheers.

[mickthefitter]

I've just thought - does the vernier move the base plate inside the distributor? So I wouldn't see anything move with the cap on and the engine running.

[KernowCooper]

Yes thats the way it works the base plate moves inside the distributor.

[mickthefitter]

Okay, I've got my engine number off the block now. 99H - 141 - H769. For some reason the little aluminium ID plate looks battered to within an inch of its existance and looks like its been run over by a steam roller at some point, but it is still readable and that's the number on it.

 

I've also now established that my dizzy base plate does indeed move when I twirl the knurled vernier knob, but to see any movement with the naked eye (and I made a little mark in the film of grease behind the moveable plate) I need to turn the vernier knob at least two full turns in any direction. Then when I put it back initially the baseplate seemed to stay put. There's maybe 1mm to 1.5mm backlash in the dizzy baseplate, but I'd assume that was resonably normal as I can't ever remember setting points on a car, in the days when all my cars had points, without the baseplate moving a little while I'm trying to tighten the screw. The car's tickover speed certainly seems stable enough.

 

I cannot physically see a screw thread relating to the vernier adjuster, so at the moment I am assuming that when people say to set the vernier in the middle of its adjustment, I am supposed to screw it as far as it goes one way till it stops, counting turns, then go all the way in the opposite direction, still counting, then set it halfway. A bit like the rough and ready method of setting the brass mixture nut on an SU. Sorry if I'm being a bit dense on this apparently simple matter. I used to be a factory mechanic and always serviced my own cars, but some car parts still hold mysteries for me. The only distributor vernier I ever came across before was on my sister's 1977 Toyota back in the 1980s, and when it started running on, we didn't have a lot of luck with that either!

 

Can anyone recommend a nice timing light? The Gunson's xenon thing I've got was the bees-knees once. It doesn't seem very bright now though, though I'd probably been staring into the light of my Ring LED inspection lamp not long before!

[carbon]

Mick,

 

Is it possible that your adv/ret can has corroded where it slides in the 25D distributor body?

 

When you move the vernier you should see the can moving slightly either towards or away from the distributor body, by about 1mm for each full turn of the vernier wheel.

[KernowCooper]

The early engines with the 25D4 distributor Id No 40931/41030 has the timing listed at 8º BTDC at 600 rpm with the vacuum advance disconnected and blocked if that helps

[mickthefitter]

Mick,

 

Is it possible that your adv/ret can has corroded where it slides in the 25D distributor body?

 

When you move the vernier you should see the can moving slightly either towards or away from the distributor body, by about 1mm for each full turn of the vernier wheel.

Hi. Sorry I'm misunderstanding some of the terminology again. What do you mean by the 'can'? I can see the baseplate move a small amount with the dizzy cap off if I give the knurled knob about two full turns, but at the moment that is the extent of what I understand should be moving when I use the vernier adjuster. Dark again in the garage now so I won't be playing with it tonight. I meant to go out to a classic pub meet but other events had other ideas!

[KernowCooper]

Here is the vacuum advance unit the can mentioned is the round chamber where the vac pipe connects http://www.simonbbc....um-advance-unit

[mickthefitter]

Here is the vacuum advance unit the can mentioned is the round chamber where the vac pipe connects http://www.simonbbc....um-advance-unit

Right, okay, I understand what I'm looking at now. Believe it or not, mine has a thin copper pipe fastened by a brass nut and an olive running over the rocker box to a rubber pipe on the carburettor, rather than the usual rubber or plastic pipe all the way through. So this - almost - flying saucer shaped 'can' is supposed to move is it, when I turn the vernier knob? I'll have to look tomorrow when I've got light in my garage.