Cold Plugs

[oldcorollas]

all electronic ignition dizzy caps are screwed down, not clipped down that's the easiest way to tell. the advance required depends on the engine. a lot of dizzys have octane selector screws on the vacuum advance unit. this can be screwed in to reduce the amount of vacuum advance, and corrected by turning the dizzy. that's if whats needed, and if it has the octane selector.

thats not true.
the 4K and 5K electronic dizzys have clip downs. neither have an octane selector.. i think the only corolla one to have an octane selector was the KE10 denso dizzy.

octane selector doesn't change the amount of vac advance, it only sets the base advance. it has no effect on the mechanical advance, and the total vacuum advance (including the base) does not change... as the octane selector doesn't affect the position of the vac advance lock nut.

there IS a locknut on the shaft inside the dizzy to limit the vac advance. this can be played with.. ie set the base advance higher for full throttle, and reduce the vac advance for part throttle.
this is for the K series specifically

[urantia]

holden apollo carb model 3s-f motor has a mechanical dizzy. Vaccumm advance for low down, and centrifugal advance for the rest of the rev range, these things seize up easily when over heated. And cost many $$ in trying to figure out why a car would go like shit.

[cambelt]

jap ke 20's and 30's had the octane selector too from what ive noticed.

[Tham]

Tham, perhas you could try runnign with less than 20deg advance.. try 15 and see if it makes a difference.

I've dropped it to down to 15 degrees of advance
and the engine does seem to run a little cooler.

Performance is somewhat sluggish though,
and climbing uphill feels like a Spitfire trying
to climb beyond 15,000 feet without a
supercharger !

Thanks.