Renovate Dizzy?
 

Any Needs to replace or refurbish distributor and coil when rebuilding engine?

Good question... :confused:

Check for play in the distributor shaft and make sure the advance weights are free and that top shaft can move on the main shaft. Check the vacuum pot that it functions. There is an old thread here somewhere going through refurbishing a dizzy. The black coils seem to last for ever....

I've found a few reasons over the years.
http://forums.pelicanparts.com/uploa...1647690209.JPG
http://forums.pelicanparts.com/uploa...1647690209.JPG
http://forums.pelicanparts.com/uploa...1647690671.jpg

Agreed it should be checked. Mine at 130K miles was fine, my friends (same 3.2) was worn to the point the rotor was starting to contact the cap, same mileage engine.

Worn out distributors are quiet a common problem with high mileage cars and can cause reliability and performance issues. If you have a stock engine and like to keep things original than rebuilding the dissi to the correct specs makes sense. An alternative would be a new programmable 123-ignition distributor which allows to select ignition and vacuum advance curves. No need to touch a healthy original coil and /or CDI-unit.

@Peveland
If your dizzy isn't worn out and just needs a full maintenance, then have a look here:
https://nineelevenheaven-wordpress-com.translate.goog/wartung-des-verteilers/?_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wap p
(translated via Google)

911SC Distributor
 

Thanks for the dizzy maintenance link - I need to swap an early distributor in my quest to “backdate” my late (‘82) SC to early SC specs (complete early CIS, large port heads, etc.) to squeeze a bit more power with my Max Moritz P&C’s, SSI’s, M1 cams etc…

Invest in MM P&Cs, SSIs, other Cams etc but sticking with an ordinary dizzy mechanical advance driven ignition is honrestly not a real good choice as its stands in no good relation.

Andrew,
Thank you for the website. I have an 81sc usa. Setting warm idle duty at 45% was recommended in your website for increased full throttle enrichment. If it's set between 45 or 55%, that represents only the smallest of turns on the fuel mixture and is additive, not multiplicative. So at idle, x+small delta. At full throttle, say 4000rpm, the fuel flow would be 50x+small delta. So very little difference at full throttle to the final mixture. The 50x full throttle vs idle is a guess, it might be lower, or higher, but the point is that it's a trace more fuel at full throttle and I don't think we could measure the improvement in terms of acceleration. What do you think?

In reality, if I was still in my 20s, I'd open up the FV electronics and change the full throttle enrichment to a variable amount within the cabin using a bypass circuit with mosfets and a 555 timer and potentiometer, I'd have to study it a bit, probably use the pre-driver signal fixed edge to drive the start of the 555 timer, set the timer to have longer period then the fv 1/f period, then tap off the peak of the ramp output of the 555 with a peak detector (diode) connected to a cap to integrate the peak to dc then use a resistor divider with a potentiometer that can be adjusted in the cabin to set the divide ratio and pass the ramp and the peak divided down dc signal to a comparator (when the ramp crosses the dc divided down signal the pulse will end, with hysteresis added so not to glitch the shut off edge) whos output would have the adjusted duty cycle, this circuit would be temperature and power supply independent, could switch it onto the output driver's input using two sets of pass gates so the existing circuit can operate when in all modes but hot full throttle. I'd probably terminate the unused existing pre-driver output to have a similar final drive device just to keep it's output's quiecent points intact when it's switched out of operation at hot full throttle, expescially if a bipolar is being used as the base takes in current, that way the existing pre-driver sees the same load impedance as originally expected under all conditions. I made a wavemaker for my aquarium years ago off the 120V supply, it worked for 25 years before the saltwater reef tank was put away. I'd start with an in cabin adjustable range of 65 to 75%, under full throttle hot conditions. The mosfet pass gates control inputs would be the full throttle switch and the greater than 35degC sensors I suppose through an And gate. Naturally, optocouplers or high voltage devices or local supply clamping using protection diodes would be included. There are high side drivers, but that's not needed here. This would be the dumb way of doing it, if the duty cycle is switched in with currents from the factory, then you can just tap into/or hijack the existing circuitry and really make it easy on yourself, the earlier stuff is overkill most likely.

Still, the wideband afr, which is additional work for the electronics gives the best hands free result I'd imagine. That I'd leave to others to design as I don't have the time or willpower for sure.

Phil

As this is not topic related, I suggest you could open a new thread.

It's okay, but I did edit the post just a little so it makes more sense to the next readers. I may take the distributor apart in the near future to clean the mechanism, hopefully you can help out if there are any questions.
Phil

I understand your issue Phil but its still totally out of topic and next readers who get into this thread expect answers regarding the distributor.
So to keep this topic clean I still suggest you open a new threat where others directly see in the subject what its all about.

This inspired me to explore the distributor. It was easy up to the three 3mm? allen bolts. I could see right away that two of them had been damaged, I tried but could feel it starting to strip. Someone else has been in here and didn't replace the bolts after they damaged them, so no luck, I'll pause till tomorrow, but it's a tight spot with very little working area. Anyone have any ideas? ez out? something else?

3mm hex key seems sloppy in general, upped to a 1/8 size, which mine is ~3.05mm measured, very snug fit, still can't break them free. My vacuum advance is perfect, the mechanical advance section looking with a boroscope through the vaccuum mount area looks very clean, someone has already done this job I think, it's not worth the risk/effort. I'll buy a timing advance innovus? with tach readout and check it in car. The intent was to clean and have a look inside the distributor if it was easy, could have been.

Phil