Exhaust "popping" on overrun?

[Joe eck]

Thanks to all for the suggestions.

I think I may have a slight leak before the silencer so will rectify that first.

I also suspect that the advance characteristics of the electronic distributer may be different from the original in that it seams to get to full advance very quickly?
In the absence of a method of accurately setting the static timing on the electronic distributer, I have had to try and set it by trial and error. I think I have it right but my lack of experience in this area may mean that I have incorrectly set timing.!

Having only ever listened to and driven my own Ruby I could probably do with comparing the running of my car with another similar car so if there is anybody in the Huddersfield or Oldham area with a Ruby who wouldn't mind me having a quick comparison some time, I would be grateful.

Thanks
Joe.

[Ian Williams]

My experience of the electronic distributors is they reach full advance too quickly. If you are determined to go down the electronic route perhaps try fitting the base plate to a Lucas unit, you may be pleasantly surprised.

[Joe eck]

Thanks Ian.
I have been in two minds wether to revert to a points type distributer to compare the two.
This would allow me to know for certain that the static timing is accurate and, although the original distributer is worn, I could compare the advance characteristics.
I feel that I may, as a result of the rapid advance, have the timing retarded ?
Joe.

[Hedd_Jones]

I put the manual original spec lucas dizzy on my chummy. The handbook for which states that once youve started it in the retarded position it should be fully advanced.

I find the bosch on my RL advances too slowly. The Bosch on the RP on the other hand is super.

[Ian Williams]

Bloody Germans! and who said they were a consistent quality manufacturer, oh yes I forgot they have also dumbed down to an Asian pricing model. Oh well I will just have to stick to my reliable restored Lucas units. :-)
Hedd, I think the hand book probably simply tries to simplify things for the inexperienced new car owner rather than what will make the car perform at its best. As we know the factory settings are a conservative safe setting which will produce performance commensurate with expectations of the period. Personally I would not recommend anyone runs around with their car at maximum advance all the time, not unless that max advance is well below the optimum setting.

[AllAlloyCup]

I once had a Morris 8 Tourer, BBO 218,  famously pictured 
On the back of the Morris 8 Profile Publication.

It was shown as what not to do to your Morris 8 !!

Mixed wire and easiclean wheels, no running boards, and go faster stripes. 
This was the state it came in when I bought it.

On one journey from Beith to Paisley circa 1967 on a narrow
country road I encountered a member of the Beith Hunt, astride his 
charger, resplendent in Red Hunting coat, hands off the reins
Having a quiet smoke.

As the Morris brakes squealed badly, I just lifted off on the accelerator
forgetting that this induced a very loud backfire.
As I got level with the horse it did indeed backfire, causing the horse to rear 
And he nearly fell off.

I slowed a bit to see if he was OK but decided to make my getaway
When he decided to chase me!!!

Later in the journey the Morris broke down with a dead battery ,where Sauchiehall St
cut Buchanan St in the middle of Glasgow city centre on a Saturday afternoon! 

But that’s another story for another day.

Regards

Bill G

[Bob Culver]

A few pointers. Power must not be judged from engine or exhaust noise. An advanced engine  sounds rorty when it may be little different, or lower powered! The manual advance range can be considerable, depending on the geometry of the linkages. On those cars the crank advance/retard is twice the rotation of the distributor body so can be estimated. For non sporty models considerably less than 20 deg BTDC crank full advance is usually adequate and prudent. Even for hand cranking it is unnecessary to retard before tdc. Neither of the auto advance distributors retard this far (the early Ruby ony 6 deg less than full advance). For the typical non sporty Seven doing most pulling in the 2000-3000 rpm range manual advance requirment is effectively constant, hence no need to fiddle with, or only very slightly. For the curious it can be interesting to calibrate the hand lever.
There were two original auto advance curves. The handbook instruction, much repeated, for the early Ruby repeats the manual instruction and is seriosuly wrong, esp so when applied to the later and similar replacement distributors.. It details the maximum difficult to determine advance instead of the static.

[Joe eck]

This weekend I have made some temporary repairs to an original DK4a distributor and removed the electronic unit in order to make a comparison.

On fitting the DK4 and altering the wiring to suit, I found one of the connectors on the relatively new coil ( fitted at the same time as the electronic dizzy ) to be cracked.
An attempt to rescue this connection caused irreparable damage and resulted in an original Lucas coil being re fitted.

Once roughly timed the first journey out was a revelation, and once the timing had been tweaked to prevent knocking it was genuinely like driving a different car. No more popping on overrun and a significant increase in power / smoothness.

Bearing in mind the DK4 still needs work to make it perfect and the timing may not be spot on, I suspect that it may have been the coil at fault coupled with a too rapid advance curve on the electronic distributer, although I am only guessing.

On inspecting the coil, the plastic around the connector appears to be very brittle, almost as if it has been heating up too much.

I intend to replace the worn DK4 parts and stick with the original set up.
These A7s certainly prevent us getting bored !

[Ian Williams]

Nice to know you have overcome your problem Joe, as I have tried to say on a number of occasions, a points system in fine fettle will perform very well and reliably satisfy the average seven owners needs.

[Ruairidh Dunford]

Good news Joe, on a similar note I have been suffering some inconvenient cutting out out in my Austin Twelve over the last few months which I have only just got around to sorting out today. The car is fitted with a taxi coil conversion, fitted at the side of the road (with wire, mole grips and tape) in Spain in the 1980s when the mag and the two spares ones we were carrying failed in the heat.

A few years later we fitted a discreet in line electronic ignition which has performed faultlessly ever since, particularly at providing instant starting. I assumed this unit had had enough after 30 years and given up. It turned out to be the coil (date stamped 1933)!

With a new one fitted normal service has returned.

I read how to test coils somewhere recently but cannot recall the procedure or where I read it.