Timing Gear

[Steves46]

Good day. Well after 6 years of active driving in my 30 Coupe, it finally happened; the car stopped running because the Rotor was no longer turning, and was towed home. Performed a couple of initial diagnostics:

1. Reversed the timing pin and manually turned over the engine however could not engage the divot.

2. Removed the spark plugs and electrically turned the engine over while using my thumb to check compression. Results: Cylinder 1 = nothing // Cylinder 2 = strong // Cylinder 3 = weak //Cylinder 4 = strong.

Although I have not removed the timing gear inspection cover to confirm, but with these findings, is it pretty certain I have bad timing gear?

[BButturff]

Following

[Will N]

Yup.

[Marshall V. Daut]

It sounds as though some teeth have stripped off the timing gear, leaving a just few to give spurious readings in #2 and #4 cylinders. I'm not sure, though, why if the distributor rotor is not turning, you get ANY readings at all. When the timing gear fails, the camshaft does not turn, or only turns intermittently when good teeth engage the crankshaft gear. The other possibility is that the distributor drive gear's pin has sheared, which would mimic a stripped timing gear symptoms. That's pretty rare, however. My guess is that once you remove the side timing gear cover (two large side bolts, a couple in the front timing gear cover and a couple on the bottom side of the pan rail), you'll find many timing gear teeth stripped. Rarely do ALL the teeth give up the ghost.
Marshall

[Steves46]

Thank you, Marshall. Yes sir that’ll be my next move to remove the side cover. Just wanna be sure. Hopefully afterwards, it’ll be crystal clear that I’ll need a new timing gear and if so, I will be ordering an aluminum type.

[Steves46]

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Update. I removed the timing gear side cover also from my vantage point. The gear looked intact, when I cranked the engine over with the hand crank the gear did not move so I suspect it’s resting on the bad spot.

[Gene F]

Don't overthink it. Swap the gear, and odds are in you favorite that will fix it. Change the oil too.

[Bruce of MN]

When that happened to me, I pulled the engine so that I could clean the pan and adjust the valves easier. I wish I had checked the main and rod bearing clearances while they were right in front of me.

[Marshall V. Daut]

It's pretty clear after you removed the side cover and couldn't get the timing gear to turn with the crankshaft that the far side of the camshaft gear is missing some teeth. To verify for sure, though, have someone hand crank the engine slowly while you use a long, thick flat blade screwdriver in between the timing gear teeth to inch it around so that the far side of the gear will face you. If you do this without hand cranking the crankshaft, you may strip more teeth off because the crankshaft gear won't budge unless acted upon. In such a confrontation, fiber timing gear teeth will always lose. You want to be able to see the far side of the timing gear without stripping any teeth.
As you suspect, it appears that you have a new timing gear in your near future.
Marshall

[Steves46]

Parts on order! Thanks all.

[Herb Concord Ca]

Hope you ordered an aluminum Gear. If not, you may be doing this again some time.

[ursus]

Hope you checked to see if the gear is an oversize one. They used to have 0.003 and 0.005 oversize gears to account for wear on the corresponding crankshaft gear.

[WHN]

Originally Posted by Herb Concord Ca

Hope you ordered an aluminum Gear. If not, you may be doing this again some time.

62 years and I haven’t used anything but fiber timing gears. I have never had to replace a fiber gear for a second time on a car. Also have not used oversized gear.

My first Model A when I was in high school had its timing gear fail. Being new to Model A’s and cars in general. We pulled the engine before finding out it was just the fiber gear. Put in new gear, reinstalled engine, drove car until college.

Enjoy.

[Steves46]

Originally Posted by Herb Concord Ca

Hope you ordered an aluminum Gear. If not, you may be doing this again some time.

Yes, I ordered aluminum.

[BButturff]

I'm very new to the Model A world having just purchased my first one this past November. Since then, I have read a few stories and watched several videos about timing gear failures. So I'm wondering if anyone has any opinion or anecdotal evidence as to why the fiber timing gears fail. It seems to me, and I'm not an engineer, that with only 8 valves, a low pressure oil pump and a distributor to drive the fiber gear should last just as long as an aluminum gear under normal use.

[ursus]

The fiber timing gears available over the last 40 years (my range of experience) have been composed of either a macerated or a laminated construction. The latter is reputed to be more durable than the former. I have never had one fail on me although I have seen gears with missing teeth that were invariably of the macerated type. It is important to have a good fit between the gears otherwise the rate of wear is accelerated.

Does anybody know how the original Ford gears were constructed?

[BButturff]

One other note for what it's worth and maybe it's already well known. The Burtz Model A engine build details and technical information lists (among other things):


7. A new steel crankshaft and aluminum camshaft timing gear.


Seems like the aluminum gear is a reasonable way to go.

[alexiskai]

Vince Falter's page covers the history of timing gears pretty comprehensively.

https://www.fordgarage.com/pages/camshaftgears.htm

[BButturff]

Originally Posted by alexiskai

Vince Falter's page covers the history of timing gears pretty comprehensively.

https://www.fordgarage.com/pages/camshaftgears.htm

Thank you. Vince's page answered many questions I have.

[nkaminar]

You can make the engine run backwards if you use a timing chain. Plus a special cam.