Thread: Ignition timing for 2l spread bore

It idles fine. It has new fuel in a new stainless tank. When it's revved, it backfires through both exhaust and up into air box.

I suspect multiple issues.

Just seems odd that it was so close to fine one day then after adjusting the timing and mix/ idle it's shot. And these things were done by Blknight, not a muppet like me!


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It's useless stuffing around with the timing if the spark is weak and/or the carby isn't set up correctly .

Do the spark first . It should throw a good strong 3/8 to 1/2" long blue spark from the coil HT lead to ground as you open/close the points...... if it isn't then something is wrong with your coil circuit.

The leads need to be good , use a multimeter to check for continuity .... those horrible LUCAS screw in connectors in the dissy cap are woeful.

I bought an expensive aftermarket LUCAS repro coil and it was absolute junk..useless, made in India or somewhere . The car backfired and jumped about missing . I used the original 60 year old one ..works fine .

Mike

Thanks Mike - I'll be going through all those things in turn. According to Dave, my carby is blocked - didn't make sense to me, since it drove near fine the day before, but he is a knowledgable fellow, so off the carby has come again. I'm getting good at this now!

I'll now do what all the info on planet earth says don't do and take it all apart to shoot carboy cleaner through it all. Think I'll have a camera and notebook ready for this phase.

Then at least once its all clean the problem has to be elsewhere.

To my original question - the manual says 10 degrees BTDC for timing - but this is for 80 octane fuel. I run 98 - should this be advanced to 15 or 20 degrees?

[QUOTE=Scallops;1547242]Then at least once its all clean the problem has to be elsewhere.

To my original question - the manual says 10 degrees BTDC for timing - but this is for 80 octane fuel. I run 98 - should this be advanced to 15 or 20 degrees?[/QUOTE]

Hi Scallops

I stand to be corrected as the saying goes, but have a read of this.

Is High Octane Gas Worth the Money? | Wanderings


" High Octane - Simple Definition
Technically, an octane rating measures the proportion of isooctane to heptane in a fuel. But as a practical matter, a fuel's octane rating relates to how much energy it takes to ignite that fuel.
The higher the octane number, the more energy it takes to ignite the petrol."

This has reminded me of another thing that does cause back fire , that is the coil can break down under load, try another 12 Volt coil in it before you change any thing else.

Coils for early, Holdens, Falcons etc are not 12 Volt as they have a resistance built into the wiring feeding the coil, from memory those coils are rated at about 7 Volts.

You need the one like they use in a 12 Volt Fergy tractor.

Such as this one on ebay

Ignition Coil Massey Ferguson TEA20 35 135 Tractor 5977

Item: 390341665721

Store: Wagga Tractor a...


Cheers Arthur

Hey Arthur - I'm running 98 octane after a thread I put up here ages ago recommended premium as it has less additive that causes degradation of diaphragms/rubber parts etc.

It was the 100% consensus then!

I'm no authority on this but I believe that higher octane modern petrol burns or combusts slowly compared to the lower grade stuff of years ago . Because of that , you advance the timing so you can account for the longer burn .

Oh BTW .............that's the crap coil I bought, a tractor one for a fergy . Not impressed at all. You can buy new non-resistor BOSCH coils .... I would be going that way rather than a garbage thing made in a sweat shop in a 3rd world country.

Mike

Originally Posted by series1buff

I'm no authority on this but I believe that higher octane modern petrol burns or combusts slowly compared to the lower grade stuff of years ago . Because of that , you advance the timing so you can account for the longer burn .

Oh BTW .............that's the crap coil I bought, a tractor one for a fergy . Not impressed at all. You can buy new non-resistor BOSCH coils .... I would be going that way rather than a garbage thing made in a sweat shop in a 3rd world country.

Mike

Hi Mike

Sorry to hear about that tractor coil not working for you, did you send it back to whom you purchased it from and what was their response?

With those, early side and overhead valve motors, is it wise to use a high octane fuel, as they are well known for burning their exhaust valves ?

Ok, then the timing should be advanced for the higher octane fuels, as the burn rate is slower and more consistent. When running the motor on power Kerosine where is the timing best set then?

Cheers Arthur