Discuss Set Dwell and Tach and Points Gap on AllFordMustangs.com, the place for Mustang enthusiasts.
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I'm going off '65 specs, but they should be the same for any 200 straight six. Dwell angle should be set at 35-38 degrees at idle with piont gap spacing at .024 to .026. Initial ignition timing should be set at around 6 degrees BTDC for a manual, 12 degrees for an automatic. Engine idle speed should be 575-600 for a manual, 500-525 (in "drive") for an auto. Sorry I don't have pictures. Also, don't forget you turn the distributor counterclockwise to advance timing on a six. Now be prepared for about twenty posts telling you to get an electronic ignition. It's good to hear someone else is doing it the way Ford built it!
To help you to understand a few things I will start the lesson with part 1. LOL
No really here goes.
When people refer to a Tach and Dwell meter, it is a tool for measuring 2 things
The first is the Tach portion - which measure engine rpm.
The second part of the meter checks the dwell (which is adjusted according to the space in between the points. This space is referred to as Gap.
I hope you are ticked, I'm just trying to help.
For your motor the Gap depends on motor cubic inches.
For a 170 or 200 cubes the gap is .027 with a dwell of 35-40 at idle.
for a 250 cube, the Gap is .025 with a dwell of 37-42.
If unsure of the motor size, I would Gap the points to .025 and you will be very close.
That is the end of part 1. Now on the part 2 - Setting the points.
First several comments:
A. - When changing points it si a good idea to change the rotor, condensor and points together. The rotor sits just under the cap and has a brass pointer. The condensor looks like a little can about 1 inch long with a single wire.
Now for setting the points. I will go on theassumption that for now you are just setting the points. If you are infact replacing, it requires removing 2 screws that hold the points and if replacing the condensor, it has a screw as well. SPECIAL NOTE - -When tightening the screws even for adjustment, just use finger pressure to tighten. You can strip the hole pretty easy if you overtighten.
Here are the steps for adjusting the points
1. - Put car in neutral/ apply e-brake - even block the tire
2. - Remove key from ignition
3. - Remove distributor cap. The cap has 2 springs on opposite sides. You place a screw driver blade between the cap and the clips and pop the clips off. (They will be attached at bottom so don't worry.
4. - Lift cap and turn it out of the way.
5. - Inside the cap remaining in the distributor you should see the rotor. May be black in color and have a brass tip. This part lifts off. It is made to only go on in one position.
6. - Now look at the distributor shaft and you will see the rubbing block. (SEe pic)
7. - Grab fan and rotate the motor. You may have to apply light pressure to the belt if it slips and the motor doesn't move. You want to get the pointer of the points at a high spot on the rubbing block.
8. - Loosen the 2 screws that hold the points and adjust the "Gap" between the 2 contacts of the points.
9. - The gap is best set using a "Feeler Guage"
10. You really should use a feeler gage available from parts stores for about $3-$4.00 .
There is a little trick to keep in mind. When you gap the points and a tightening the screws, don't use to much force because you could strip the holes and also you could change the Gap.
I am attaching a picture of a the inside of a dizzy but I think it is an 8 cylinder if i recall. Your's will be very simillar.
After setting points - reassemble (Don't foget the rotor and be sure it sits all the way down (Look for the groove in the shaft.
In the picture - -A points to rubbing block or lobes
B points to where you adjust the space (Gap) of points
C. - is the condensor.
Screws E and H need to be loosened to adjust the gap. I try to just lightly loosen screw E and loosen screw H more. Kinda use E as a base and use the H screw to allow more movement of the points. When you look at the base of the points near the contact area (B) you will see a notch that allows you to pull or push the contact area open or closed.
I think you'll be OK but ofr now..... Class Ends... LOL
If any trouble just post...... Print DAd
Last edited by Print Dad; 12-29-2009 at 12:15 AM.
Reason: Forgot picture
My dizzy has made it 44 years. I'm two years older than it is and wish I ticked as good as it does. Don't feed it if it isn't hungry. Points and condenser will easily last several years and you already know they don't cost much. Print Dad is right. If you spend the money, read the fine print. Pertronix have their own sceletons and you don't want to spend that kind of cash twice.
Hi again. I have pertronix in my car, but, I also keep a new set of points and condensor in the glove box. The pertronix unit is extremely sensitive to electrical spikes, so, if you ever have to jump start the car, or, your charging system does something stupid and sends a surge through the system, it can shut you down. I'm seriouslt considering going back to the points because the breaker point system and I have no surprises left for each other, while I am absolutely clueless as to how the pertronix thingy does what it does, and I really, really don't like having to trust a component that I don't understand.
Even I, with a good understanding of the Pertronics unit, have problems with using one to replace my points. In the early 70s I had built a unit from Popular Science that was called a "dwell extender" and installed it on my Falcon. The car ran great and didn't require any adjustment other than to make sure the points open and close. The dwell was completely controlled by the circuitry. It was a simple timing circuit that gave the coil far more impulse than it could get at any rpm with just the points. It improved the mileage and power.
I just recently recovered the information that I had lost and plan to build three of these units - one for each of the two Mavericks that we use most and the Mustang that I am building. That way I get to keep the points and get the advantages of "electronic ignition" without the associated problems that can occur by simply leaving the ignition on for too long without the engine running.
I couldn't agree more with Veronica about trusting something you don't understand. Also, with a spare set of points in the glovebox and tools in the trunk, I can be rolling again in an hour instead of waiting for a tow truck. (That's what happened with my last Pertronix unit!)