1,3,4,2.

[Mixer]

Has anyone come across an alternative firing order than 1,3,4,2, and if so why?. I have acquired a 7 Opal and it was running very sweetly, but since having the starter brushes and bearings replaced, for some peculiar reason I lost  a spark to the plugs, doing the usual checks of ingition to coil and power to the dizzy, assuming the firing order to be ok I decided to fit another dizzy with the desired result of a heathy spark.
In my excitement to get her going I connected the HT leads to the appropriate plugs to fire 1,3,4,2 and checked the flywheel  for TDC and when turned over  had a backfire through the carb -much to the wifes alarm.I then checked whether 180% out and the carb alighted again when turned over. So hence the opening question. Any comments will be appreciated.

["Slack Alice" Simon]

Getting the timing right can be a bit hit and miss.

Both my cars have manual advance, so easy to play about with.

80 odd years on, the play in the drive train often means that the timing doesn't set up as in the book


Silly mistake that is possible: have you got the firing sequence right for the rotation direction of the distributor?


Sevens will run a bit, or backfire a lot, almost whatever the timing is.


Some distributors have the earth return through one of the screws holding the base down to the casing, which may be intermittent.

Others can develop a tiny crack in the connection on the base itself.


Both faults will give you erratic firing, and may not show up on a testmeter.

[Steve Jones]

No 1 is the front plug. Have you counted from the rear?

Steve

[A G Wood]

1243 for some Ford engines, that's the only one that comes to mind for inline 4 cyls. Make sure you are timing on the correct cylinder phase too, you want the end of compression stroke TDC #1, not the end of the exhaust stroke TDC #1.

[Ivangardiner]

Maybe the replacement distributor has a cracked cap.  Also, my Bedford camper had an enforced 3 months parked outside, and the contacts inside the cap got quite corroded.  My theory is that, with the one contact which was corroded worse than all the others the spark would say "too hard to get across there, I'll go to the next nearest one instead".  Fitted a new cap and no more problems.  Still only a theory of course...

[Tony Press]

Has anyone come across an alternative firing order than 1,3,4,2, and if so why?. I have acquired a 7 Opal and it was running very sweetly, but since having the starter brushes and bearings replaced, for some peculiar reason I lost  a spark to the plugs, doing the usual checks of ingition to coil and power to the dizzy, assuming the firing order to be ok I decided to fit another dizzy with the desired result of a heathy spark.
In my excitement to get her going I connected the HT leads to the appropriate plugs to fire 1,3,4,2 and checked the flywheel  for TDC and when turned over  had a backfire through the carb -much to the wifes alarm.I then checked whether 180% out and the carb alighted again when turned over. So hence the opening question. Any comments will be appreciated.

Deja Vu all over again 

 see : 1,3,4,2. 25th  July

[Robert Leigh]

Rileys are 1243 as well.

[John Barker]

The cylinder firing order of 1,3,4,2 will be determined by the cam shaft which controls the opening and closing of the valves. On the compression stroke the valves will be closed in order for the spark plug to be timed for the ignition of the fuel.
  To change the firing order will involve a different cam shaft setting for the valves to be in synchronizing for the compression/firing stroke.

---

There are different settings given for the amount of advance on the Austin 7 engine. "Bill" Williams book gives the setting of one and seven eighths of an inch, and The Austin 7 Companion a setting of one and a quarter inches.
I have set our Austin 7 with manual advance / retard to one and a half inches, although this has a Phoenix one and a half inch crank. The advance setting may have something to do with the back firing. I am unsure if the mixture setting on the carburettor would cause this.

[Bob Culver]

Spark advance has been covered at enormous extent previously. Auto advance cars with the misinformation in the handbooks, the difficulty of establishing full adavnce, and myriad combinations of worn and wrong parts can be a puzzle. but the manual cars are delightfully simple as can find optimum in action. The minimum advance to acheive performance or a little less is the ideal crank stress increases hugely with spark advance. For non sport unmodified cars driven as originally 1 1/2 full advance is usually plenty.

[Tony Press]

Has anyone come across an alternative firing order than 1,3,4,2, and if so why?. I have acquired a 7 Opal and it was running very sweetly, but since having the starter brushes and bearings replaced, for some peculiar reason I lost  a spark to the plugs, doing the usual checks of ingition to coil and power to the dizzy, assuming the firing order to be ok I decided to fit another dizzy with the desired result of a heathy spark.
In my excitement to get her going I connected the HT leads to the appropriate plugs to fire 1,3,4,2 and checked the flywheel  for TDC and when turned over  had a backfire through the carb -much to the wifes alarm.I then checked whether 180% out and the carb alighted again when turned over. So hence the opening question. Any comments will be appreciated.

Deja Vu all over again 

 see : 1,3,4,2. 25th  July

I have just noticed I received a negative reputation from nrzam for this post back last year- why I ask ?