Classic cars forum & vehicle restoration.

[FIFTIES CRUISER]

Hi when I perchased my mark 2 Ford Zephyr I was told by the owner the engine had been converted for unleaed fuel. On collection the tank was low and I filled up with unleaded. As there was no proof the conversion had been done I subsequently used leaded 4 star. From then on the engine didn't run as well, symtoms of misfiring. Recently I've replaced the points and condener and set the timing statically using a light bulb on the LT contacts on the coil. Timing marks lined up with Number one piston TDC on compression. I had to turn the vernier knob on the dizzy many notches towards retard to make the bulb light. The engine starts and ticks over and fast idles really well now. I believe leaded 4 star fuel requires a more advanced setting than unleaded. any views welcome.

thanks

[Uncle Joe]

The lower the octane rating of a petrol, the more likely an engine is to 'pink.'

A misfire due to a change in fuel is more than likely a symptom of other problems.....

UJ

[mexico]

It isn't that leaded petrol requires more ignition advance it's just that it can accomodate more advance which produces more power. Have you tried going back to unleaded fuel ? It might just be a coincidence that the fault appeared when you changed to 4 star.



Number Plates

[Uncle Joe]

Nope. That unleade fuel requires a timing change is just a myth that is sometimes heard. It was brought about by the fact that some oil companies took the chance to lower the octane rating.

UJ