Dual point dwell

[Brandon]

It's been a while since I set my point gap, but in need of a tune-up.

Running a stock C5AE-12127-E distributor on my 67 GT500.

My points were at .012" and dual dwell was at 34 degrees. For the 67 428, the manual says .019-.021 gap with a combined dwell of 22-24. If I gap them both to .019 my dwell is too low, but then a dwell of 22-24 seems low from other cars I've worked on.

I assume I set the primary to .019 and adjust the secondary, thought I think last time I set both equal by trial and error until the dwell was in range, but hoping someone can refresh my memory.

[shelbydoug]

It's been a while since I set my point gap, but in need of a tune-up.

Running a stock C5AE-12127-E distributor on my 67 GT500.

My points were at .012" and dual dwell was at 34 degrees. For the 67 428, the manual says .019-.021 gap with a combined dwell of 22-24. If I gap them both to .019 my dwell is too low, but then a dwell of 22-24 seems low from other cars I've worked on.

I assume I set the primary to .019 and adjust the secondary, thought I think last time I set both equal by trial and error until the dwell was in range, but hoping someone can refresh my memory.

You can screw with the points forever in attempts to get those dwells. That is up to you?
I would tell you to set the points with a feeler gauge and leave them alone.

Some of these distributors I've seen are showing signs of wear that will throw off the point setting.

The points cam must ride very accurately on the distributor shaft to maintain a accurate points setting. If it is off .001" then the points will be off .002".

It may need to be knurled and reamed?


I just had a Boss 302 distributor here that had ,004" play which made it impossible to set the points accurately.

[roddster]

If the distributor shaft top bearing is worn it is not that hard to replace it yourself or send it out for rebuilding.

 Also, often enough you have to fiddle with the gaps to get the swell right on.

[Brandon]

I'm actually getting very consistent results for both gaps and dwell. My question is whether 22-24 combined is what others set (seems low), and others are setting both points at .019"-.021" and ending up with 22-24 dwell, as mine require the gaps to be less than .019" to end up in that range.

Or are you both suggesting I'm needing to go less than .019" to get to the 22-24 dwell range because my distributor shaft top bearing is worn?

[rockhouse66]

Is the dwell number with both points active?  I don't recall and I am away this week and don't have the manual.  I know when I run a dual point on the Sun machine I have to isolate one set of points (piece of cardboard across the contacts works).  And I agree to just set the gap as accurately as possible and don't worry too much about it.  I would also say if you can push on the side of the shaft and see the point gap change, it needs a new bushing.  If it is only a tiny bit, you might be okay but I would not close up the gap to get a better dwell reading.  Or run a Pertronix which doesn't much care about a little shaft movement or dwell numbers.

[Brandon]

Here's the 67 manual I have which specifically shows .019-.021" breaker gap for all models and 22-24 degrees combined for the 428.

[TLea]

22-24 is for transistorized dual point. conventional should be 30-33

[Brandon]

Interesting.  Any idea why it refers to 22-24 rather than 30-33 in the manual?  The original was obviously not transistorized, and it doesn't make any reference to it.  Where did you get 30-33 from?

[Brandon]

I would also say if you can push on the side of the shaft and see the point gap change, it needs a new bushing.

If I push on the side of the shaft, I can see it move, and I can feel a point gap change with .001" feelers, but can't measure a change with them. Meaning the play at the points is less than .001".

[rockhouse66]

I doubt that small movement would result in anything noticeable in the engine performance.  

[TLea]

Interesting.  Any idea why it refers to 22-24 rather than 30-33 in the manual?  The original was obviously not transistorized, and it doesn't make any reference to it.  Where did you get 30-33 from?

The transistorized refers to the R code Galaxies which used same distributor
Where did I get 30-33 from? Working on Ford dual points since I was 13 

[Brandon]

Interesting.  Any idea why it refers to 22-24 rather than 30-33 in the manual?  The original was obviously not transistorized, and it doesn't make any reference to it.  Where did you get 30-33 from?

The transistorized refers to the R code Galaxies which used same distributor
Where did I get 30-33 from? Working on Ford dual points since I was 13 

But this is a 1967 Shelby GT350/GT500 Owners Manual, which wasn't transistorized. I'm not challenging your assertion because 22-24 seemed low to me, but surprised they'd have this big of a misprint.

[JD]

Hope this helps, page 60 of a 1967 Shelby GT350/500 Owners Manual...

[98SVT - was 06GT]

I've "fixed" cars with badly worn upper distributor bushings by installing a Pertronix electronic ignition. They use a magnet to fire the sensor and are not very sensitive to the air gap moving around.
https://pertronixbrands.com/products/pertronix-1281-ignitor-ford-8-cyl

[FL SAAC]

The answer to ALL your issues is called petronix.

It's all underneath the cap, no one will ever know.

Set it and forget it.

Make sure you get ALL matched components

Best of luck