pertronix and dwell

[47silver]

do you have to set the dwell with a pertronix ignitor electronics points set? if not does the pertronix do it internally?

gary

[72 four door]

It does it internally as you would say With points you would have to.

[RoninLB]

Originally posted by 47silver
do you have to set the dwell with a pertronix ignitor electronics points set? gary

I think a good eyeball of the timing of each plug wire, w/a timing lite, won't be a waste of time.. just to confirm that the unit is perfect........... Ron

[47silver]

thanks
ill let you know what i find with the wires.
gary

[Targa Dude]

Hi Ron, Are you running a Petronix ignitor in your 77? if so what do you think of the unit?

Thanks

Jorge (Targa Dude)

[ruf-porsche]

Dwell is a function of the point gaps. Increasing the point gap decrease the dwell and decreasing the point gap increase nthe dwell.

With the pertronix ignition system, the point is replace with magnets and an a pickup that can read the magnets.

[47silver]

the dwell then is when the points are closed in order to charge the coil i assume. if that is the case then does the pertronix allow the coil to charge the optimal amount of time? if not then it is possible that the coil is not charged completely with a pertronix? i plan on installing the one we got from pelican this weekend.

[Early_S_Man]

47 ...

Dwell is irrelevant in so far as the functioning of the Bosch CDI-system is concerned. The risetime of the ignition pulse from the CDI-unit is only a couple of microseconds, maximum, so the dwell angle changes caused by wear of the points' rubbing block serves only to alter the ignition timing, not the spark duration! Spark duration is fixed by the design of the CDI-unit, and is a constant time, regardless of engine speed or dwell angle variations.

Be sure to carry a spare set of points in your glove box ... in the event the Pertronix fails ...

[RoninLB]

Originally posted by Targa Dude
Hi Ron, Are you running a Petronix ignitor in your 77? if so what do you think of the unit?

No, I'm not running one. and don't want to..

Many guys love them.. good for them.. I'd rather keep it simple.. I don't want anything else to worry about in an ignition failure.. I'm not saying it's NG.. only not what I need, or want..

So, the points wear block breaks in after 1,000mi w/dizzy grease on the rubbing block/no problem.. then points are good for big big miles/great/points are only a trigger/low current.. and pitting is not an issue/great. but if pitting, then it's a sign of a bad ground for the CD box/great..
so a timing light at plug change time/it's done anyway..

but I'm not saying don't do an ignitor.. it's my personal preference for not having one.. I'd also rather have carbs than EFI/$$ not an issue............ Ron

[47silver]

thanks everyone for the posts i appreciate it. ill let you know if i have problems and ill carry that spare set.

[Porschedude]

I ran the standard point system for 5 or 6 years on my ’72 911T and was changing or chasing the point dwell all the time. When it was timed right and the points and condenser were fresh, the engine ran like a Swiss watch, but when the points needed attention, I’d pull the distributor and set it up on a Sun Distributor Machine and set the points and check the advance curve. Whenever I changed the points I used the Bosch Distributor grease and applied the proper amount to the rubbing block. Once the dwell was set, I reinstalled the distributor and timed advance/retard and everything was great, until the next time. When the Pertronix came out for the 911, I bought one of the first ones they shipped and installed it with little difficulty. After the installation I drove the car over 100,000 miles in 8 years and never even had to time the ignition. Every time I checked the timing it was always right on the money. It mated well with the Bosch CDI and the tachometer worked fine. It never failed to start and always ran well, unless it needed the sparkplugs changed or the valves adjusted.

One less thing to worry about in my opinion.

[47silver]

porschedude
thanks, cant wait to install it. i run the msd 6al so it should not pose any problems either.

gary

[47silver]

Hi,

if you see the above posts, ther are over 6 years old, just wanted to let everyone know that they are still working and without any hassles.

[911pcars]

Ignition points tend to bounce off of the dist. cam lobe at high rpm thus producing erratic spark. Heavy Duty contact points can reduce this but at the expense of rubbing block wear. If one wants to service and maintain the correct dwell/point gap and ign. timing, points are simple and basic.

Electronic triggering devices like Pertronix, Crane, etc. don't "bounce".

Sherwood