Hi,
All the below might be a bit out of order, but it should give you a full story ... i hope ...
i checked on a few distribuitors lately and most of them have the same problem which come with age (40 years!)
a) points and condensor burned (easy fix, replace, which should be done every 10 thousand miles anyway)
b) vacuum andvance not working (easy fix, replace)
c) the spindle in ditributor (under rotor) has play ->overhaul or new new distributor
d) the humps working the points (under the rotor) are nearly gone ->overhaul or new ditributor

to a)
you can see at the points surface (where they click together). When it's kinda burned, not smooth surface, the condensor
is most likely gone. Change both. If condensor is gone you'll get a spark between the points resulting in surface to go. noone wants that.
Dwell will never be stable

to b)
unscrew distributor cap. disconnect thehose that goes from distributor tocarburator at carburator side.
(if you have a fixed line, unscrew at vacuum advance and attach a rubber hose to vacuum advance)
Suck on the hose, cable like on a straw. what should happen is:
- the vacuum advance moves the whole contact breaker plate (most old ones do that still)
- when you have a vacuum sucked, put your tongue onto the hose to block the hose. The vacuum should hold. That means the breaker plate should stay in advanced postition.
Only when you release the vacuum created the plate should move back. If it's not holding the vacuum the membrane is ripped.
If it's not bulging at all when puting vacuum on it, it severly damaged. Either way. replace

to c)
when you're able to move the spindle where the rotor sits on, you'll never get a correct sparktime throughout the cylinders, dwell will be inconsistent ---> rubbish fuel economy and performance

to d)
during the years they just flatten. I usually grease them with a TINY bit of axle grease. When they're uneven it results in same as c).

So from all that and what your distributor looks like: get a new one.


Now for the choice: points or electronic.
===========================
there is only 2 reasons for point distributors
1. back to original
2. easier to fix once something goes wrong. It's mechanical. I once fixed my distributor with a few twigs to hold the braker plate in place to get me home at least. Then I screwd the whole thing down.
It was rubbish, but getting you home is great !


Every other aspect speaks for "Electronic", breakerless (i shouldn't say pointless) ignition.
1. You most likely will get w whole new distributor, which will resolve c) and d). the spindle will have no play and in brekerless ignition the humps don't exist anymore
2. the dwell is not static throughout rpm range:
If you have a new good distributor, which works with points. You'll need to adjust dwell at idle rpm. Either with dwellmeter or with a feelergauge.
The dwell will be exactly the same with 4000rpms, again throught the machanical nature.
the humps will dictate on when the breaker opens or closes. rpm has no influence on opening/closing time relateion in percent.
(dwell is the opening period ina full period). You have 360 degrees when the rotor goes around once.
All 8 cylinders spark in that cycle. So you have 8 periods being 45 degrees each. In this 45 degrees the breaker has to be closed for a specific amount of degrees to charge the coil, and at the exact moment the breaker opens you'll get the spark.
Again the relationn between time open and closed in that period is known as dwell. If you adjust the breaker such that it opens longer or shorter you adjust the dwell.
As I mentioned before: the cylinder gets the spark exactly when the breaker opens. So if the dwell gets out of adjustment, which will happen during time unless adjusted regularly, the ignition timing will get out of whack as well.
therefore: points have to be adjusted regularly, otherwise ignition timing is off, less performance, less fuel economy.
As there are no points in electronic ignition you can see why they're favoured.
What most prople might not know is the fact that the ignition module (pertronix etc) is actually able to adjust dwell throughout rpm range.
Another + for this.


Vacuum advance and so called street/racing ditributors.
================================================== =====
When picking a distributor you will get the choice of a "street" and a "race" distributor. the difference between them is that the vacuum advance is missing on the "race" model, and for that you pay _more_ ?

There is a huge misconception as well.
a) racing sounds like: this will be quick
b) the mentioning of not allowed on pollution controlled vehicles sounds like: more pollution/more quick as well.
This is all wrong! The theory behind that is:
if I have a drag racing car, I step on the accellerator and will not bulge from that pedal until finish line. thats all my car needs to do. For this I don't want a vacuum advance that messes with my ignition timing. If this is the case and you build a drag racer, go for it.

But if you (like me) are driving your car on a road, where you have traffic lights, highways, hills etc then do NOT.
here's the reaons why:
lean mixuture takes longer to ignite/burn
lean mixure you'll have standing at traffic light in idle. You'll have it as well when cruising with 65miles on a highway. The only force you have to beat there is the force for keeping car at speed (rolling friction) and the wind.
for this you hardly need 50 of your 200+BHP. very lean mixture in this situation. so when you cruise on motorway you will have increased vacuum, resulting in ignition advance.
The autolites and most other carbs hook to ported vacuum.
I could write about 4 pages only on this, but here's the short story:
only when you drive with full throttle more than 90% of your time->go for race distributor without vacuum. But those people know anyway.
if you're driving the car like any other person, with the occasional or quite often foot on the accelerator go for the street model (don't believe a salesperson that a race distributor will be more fun, better, anything).

a vacuum advance this will give you: smooth idle, great fuel to mile economy. I bet at least 30 miles per tankfill.
It will handle ALL driving situations you come across, not only full flat out.


which distributor to get, which coil:
=====================================
If you have money in your pockets and this is not a question, most people would poijnt you to the MSD sets. they're just great I hear.
I never had one, but saw/drive two of them and all the ownerswere wellpleased.
If you want to go original all the way, then go for a rebuilt one with points.
I personally took something in between, which I'm happy out with:
the pertronixII distributor, together with flamethrower coil.
- looks kinda original as the coil is still external and don't have those but-ugly huge things (squar coil) on top of the distributor
- gives great fuel economy and improved performance (at least in my case both improved greatly)
- it's a very easy swap
i added new spark leads for that (bigger diameter) at the same time. looks good and is recommended for higher voltage.

If you ask around, which ditributor/coil system to get you'll here different opinions from all around.
This is all correct, there are preferences. I chose mine. But to sum up the article:
If you want original, go for overhauled original. Any other reason: stay away from points, go electronic ignition.

just my humble opinion to this ...

Kalli

 

oh.. and btw: if you have rust in your distributorn, this usually results from when condensed water (after rain/wash) gets under your distributor cap resulting in a very very hard starting of engine). Most likely you have to wipe your cap with a cloth after every rain before you;'re able to start that car ... Those rust particles and water wuill fly around in your cap). reulsin gin the spark going anywhere, but not where the rotor intends it to go (misfiring) ....

 

i found out that i have a K code dual point dist. im my car. i guess someone swapped it out years back cause my car sure aint a K code.

 

Wow, save that. You may not want to use it (although there's nothing wrong with it), but I'm sure you could sell it for a pretty penny to a K code owner.

 

changed mine last night to petronixs-took about 25 minutes...easy and it started right up ! good luck scott

 

Kalli, thanks for going into so much detail. Really helps me understand what to look for in a distributor and will help me make an informed decision on what to do with mine.

 

by the way, mustang monthly has an excellent article on street survival in an early model mustang that will provide a simple guide of the thing that might need addressing. http://www.mustangmonthly.com/techar...ide/index.html

 

not a bother. forgot the most important.
in case you ditch your old ditributor, make sure to keep the old one. you might want to have it back to original in 50 years time or when seeling it the buyer will be delighted to hear you kept it

Kalli

 

Kalli, how do you know if its an original distributor? I pulled it out and I can see its an Autolite. Theres other numbers stamped on the stem too. Does this sound like an original to you?

 

I don't know anything about the datestamping. so someone else might help to find out.

the fact it's autolite and that your distri actually looks it's 40 years indicates that it probably is the original distributor.
another thing to mention:
changing the distributors is usually 30 mins work maybe an hour if you don't know and go through every step carefully, but sometimes here on the forums you hear about people who have a VERY hard time to remove their rotten distributors. They're usually rusted to the block which will give you a hard time. Persistant people resolve this with vice grips and blow torch. Don't use hammer to try and knock the thing out !Most important thing is:
The distributor needs to be able to turn to be able to being pulled out.
Before checking on what I wrote next be sure the make proper markings on the exact ditributor position. so you can turn it back where it was).
There's a clamp holding down the distributor. loosen the clamp and see if you can turn the ditributor in both directions as if you are adjusting ignition. If you can I don't expect trouble pulling the thing out (don't forget to tighten the thing)

Kalli