Problems gapping points on QD-19

[fleetwin]

h20lew wrote:

I tried the way Mumbles described and that by far is the best way to do it. I’ve been doing it before by disconnecting the wires at the points and using a flashlight connected to the points and ground like some of the manuals show. The downside on that method was you always had to reconnect the wires and that brought in error like Fleetwin mentioned and you couldn’t really go back and verify it without disconnecting it all again. Maybe I’m misinformed, but I think the disconnect (no pun intended) is that most of the manuals on this were made before digital multi-meters were around and so the better method with the multi-meter and leaving the wires connected isn’t described in the common service literature from that era.

Just checked a 68 OMC manual, it definitely says to remove all leads from the breaker point terminal, which makes sense and is the “correct” way to do it. The key to success with Mumbles approach, is to have an ohm meter that can accurately show low resistance readings. The problem that I see most often is that many digital meters are erratic in this low range, admittedly I don’t have a high quality digital meter. When it comes to accurate readings in the very low range, I really like my very basic stevens AT101 analog meter. Opinions will surely vary, the important thing is to have a meter that is accurate in the low range and understanding how to set it up correctly. We are talking about a very small difference in resistance readings here, about one ohm, so confusion caused by inaccurate meter set up/readings can certainly create unnecessary confusion and frustration. The other thing to keep in mind is that we are not working on aircraft engines here…Trying to achieve absolute perfection when setting up the points is frustrating indeed, especially when crankshaft and mag plate sideways slop are factored in. I am usually disappointed when checking point set up with the timing light while running, after static set up with the ohm meter, never the same…Maybe using Mumbles technique will help…

[fleetwin]

I fear I have gotten off track here. The original post mentions not being able to use the offset adjustment screw to adjust the points….Adjusting the points on these 10hps is difficult, because the point cam is on top of that spring/collar set up….Pretty tough to push the cam down under spring tension so the cam is on the breaker point arm…I often worry about pushing the cam down on top of the breaker point rubbing block and damaging the points. Yes, you can remove the spring/collar, but that involves removing the flywheel key. I usually adjust the points with the flywheel in place, using the inspection hole in the flywheel. The other thing to keep in mind is that you have to leave the adjustment cam screws somewhat “loose”, otherwise they might bottom on the mag plate during adjustment limiting the range of point gap adjustment.

[Buccaneer]

I’ve had a “buzz box” for years that I like to use. The nice thing about those, you don’t
have to disconnect the wires from the points. Mine is a different brand from the one
in the video, but works the same way.

https://youtu.be/rqZWiFIVI5g

Prepare to be boarded!

[aquasonic]

Another benefit of using a timing tool on the ten horse OMC classics, is that the timing tool compresses and holds the expansion spring and cam in place. Just slide the tool on the crankshaft and flywheel key, and hold it in place with the flywheel nut.

The Ohm meter needs to have a setting for 1 Ohm in order to pick up the subtle difference in resistance when the points just open. I have a multimeter that Frank R recommended some time ago, and was very reasonably priced. After using it for a while, I found that it also has an audio setting. The great thing about the audio, is that you can fully focus on the point adjustment, and just listen for a change in tone when the points open.

• This reply was modified 3 years, 12 months ago by aquasonic.

[fleetwin]

aquasonic wrote:

Another benefit of using a timing tool on the ten horse OMC classics, is that the timing tool compresses and holds the expansion spring and cam in place. Just slide the tool on the crankshaft and flywheel key, and hold it in place with the flywheel nut.

The Ohm meter needs to have a setting for 1 Ohm in order to pick up the subtle difference in resistance when the points just open. I have a multimeter that Frank R recommended some time ago, and was very reasonably priced. After using it for a while, I found that it also has an audio setting. The great thing about the audio, is that you can fully focus on the point adjustment, and just listen for a change in tone when the points open.

• This reply was modified 3 years, 12 months ago by aquasonic.

So true, using the timing fixture to hold the cam down solves that issue….

[Matthew Pieklik]

I had Blue Streak points that had the rivets loose. I would tighten the wires on and the insulator would move ever so slight and ground out the points.

[RetiredGunny]

Okay, like I said I was going to do, I ordered a set of Sierra points and put them in this morning. To be honest, in my own opinion, I was was impressed with the set of points I received. They sat on the cam with a pronounced gap that was easy to adjust, using the continuity method with my multi-meter. The actual points themselves sit squarely on each other, and the oiler pad actually had oil on it. The kit also contained a pack of dielectric grease, that went unused. So far, barring the actual performance, I am extremely impressed with the Sierra’s over the OMC.

Thanks, everybody for your assistance and recommendations ~ This has been quite a learning experience.

[frankr]

Well that certainly is a different report than what we are accustomed to hearing about Sierra stuff. Glad to hear it.

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