MTFCA Forum

I installed my new Tru Fire system today and have constant backfiring through the carb when trying to crank the car (1914). I had to re-set the timing as it was way too far advanced from the setting with my New Day timer. Once it starts it runs fine and gives repeated free starts, but still backfires when I crank start it. I followed the instructions to the letter. Any comments? Bruce

It does't/never has done the same on my Haigh's chocolates van for 30 years now. I know this may not help, but it is an indication that a True-fire is a reliable product.

Allan from down under.

The timing may still be too far advanced. Count on having to reset the timer position per the instructions, ignore the part about checking it and maybe leaving it alone. Be sure that the #1 piston has gone 1/8 inch back down the bore after passing TDC before you set the initial timer position.

I couldn't stretch the stock timing rod enough to push the timer over to the correct position without the rod hitting one of the timer contacts, so I ended up having to fabricate a longer than stock timing rod, see the attached sketch.

The TrueFire puts out about 4,500 Volts or more that has to be equally divided between two spark plugs, 1 and 4 or 2 and 3 have to fire together.

The plug gaps are critical and must be the same!

Like wise 3 and 2 or 4 and 1 fire together.

One is considered a Waste Spark and that cylinder has just lost the charge, fired and was dumping the waste in the cylinder.

If your Timer is not properly connected, you may end up firing 1 and 2 together, and one will be providing the backfire.

Should a spark plug misfire, that Waste Spark will dump gas into the exhaust manifold and that gas will be lit in the manifold.

Looks like my coil box is the culprit that can't handle the higher voltage,.... or the spark plug gaps which were not identical. I put everything back to original (New Day timer) and it runs perfect again on battery and magneto so I'll be selling the Tru-Fire set-up if anyone is interested.

You may only need to dry the box in an oven for an hour or so.

Replacing the wood with all the contacts on with a plastic one is still your lowest cost option.