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MG MGA - Spark Plug Gap

I believe the manual calls for .25 gap on spark plugs. I was using .30 with a Lucas Sport Coil with the standard point setup before my rebuild and that seemed to work just fine. After my rebuild I was buying spark plugs at the rebuilder's shop and I mentioned I had a Lucas Sport coil already installed. It was then suggested I could set the spark plug gap at .40, however thinking that was too much, I started with .35. At .35 gap (car on jack stands in the garage) the motor falters(misses) when revving up the engine. It will run fine at a steady rpm, just won't rev up as it should. I have the standard point set up.
Maybe the person who suggested I open the gap to .40 thought I had pertronix ignition along with my Lucas sport coil.

Now my questions: With a Lucas sport coil and standard point set up, what have you folks found to be the most optimum spark plug gap?

With the Pertronix set up and Lucas Sport Coil, can one go to .40? Seems like an awful lot.

I intend to reduce the gap back to .30 as soon as I get a chance and see how that works.

thanks,
Ray
Ray Ammeter

On a rolling road using an a Series engine and a lucas sports coil (yellow) I found that whilst the difference in plug gap was almost negligable I did eventually convince myself that a gap of 32 thou was optimum. Perhaps I needed to find some gain in order to justify the rolling road time!!
Bob (Robert) Midget Turbo

The larger the plug gap, the higher the voltage developed at the coil. That voltage is applied to everything downstream i.e rotor, disty cap, wires plug connectors and, yes, the condenser and points albeit at a lower level. With all the problems with rotors these days, I wouldn't go too much wider than .030". And the std side entry cap was never designed for the higher voltage either. Comparing the Sport coil to a std coil, the Sport coil will give more "energy" at the plug keeping the plug gap the same.


Chuck
C Schaefer

This thread was discussed on 13/10/2008

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