Timing Gear Replacement
 

Model A Gurus - I need some advice:

Attempted to remove the timing gear on an engine rebuilt 40 years ago but on the shelf and never installed. Assembled the engine, but saw a small chip on one of the teeth on the fiber timing gear.

Tried the special tool and long bar with a pipe over it for maximum leverage and the nut on the timing gear will not budge. The next step would be to use heat.

Now I feel like I am at a point of proceed or retreat - like the Wagner guys marching on Moscow last week.

Is this worth doing? Is the small chip in the one tooth requiring drastic measures applying heat (afraid of damaging something else) worth the effort or leave it alone?

Please see the photo!

Re: Timing Gear Replacement
 

Replace it. That chipped tooth is just the tip of the iceberg. That gear is going to go bad on you. Now is the ideal time to change it.
In the past when using a hammer and chisel wouldn't budge the timing gear nut, I used heat - with mixed results. It's invasive, messy and the nut still has to be driven off afterwards. I now exclusively use an impact wrench with the special oval socket sold by all vendors. No more strained backs or skinned knuckles. 'REALLY works well if you have access to compressed air and an impact wrench. They are cheap enough these days that if you have a lot of Model A restoration work to do - especially disassembling unrestored cars - and impact wrench is a might handy tool to have.
Marshall

Re: Timing Gear Replacement
 

Thanks very much for your advice. I do have an impact wrench and the special socket for the nut. I will try that first before any heat.
Thanks again.

Re: Timing Gear Replacement
 

I find it best to use 2 slats of wood and two "C" clamps. Place a slat on each side of the cam gear and tighten with the "C" clamps. The slats will act as a stop against the block or pan. Crank your compressor up as high as it will go and use the impact wrench. This method always works for me.

Re: Timing Gear Replacement
 

End of story, lifetime gear and six sided nut if it isn’t.

Re: Timing Gear Replacement
 

One more piece of advice: Before removing the old fiber timing gear, use the hand crank to turn the crankshaft against the timing gear until the timing index mark and dimple line up opposite each other. This is where you want the crankshaft to be vis-a-vis the new camshaft gear's dimple. This is NOT TDC, so don't look for #1 piston to be at the top of its cylinder. If you don't bump the crankshaft in the meantime, the new camshaft gear will slip over the two dowel pins and line up exactly opposite the crankshaft gear's index mark. You can't put the new gear on 180 degrees out of alignment! The dowel pins are offset so that the gear can ONLY go on one way. Just kind of line up the camshaft's dimple when installing the gear to get in the ballpark for alignment. Hand crank the engine afterwards a couple times to ensure the two marks are opposite each other every other crankshaft revolution.
By the way, if you can't see the crankshaft's index mark because of an oversized slinger or a faint stamping, it's located on the first tooth to the RIGHT of the keyway in the crank. So, you don't need "no stinking" index mark to align the crankshaft and camshaft gears. :)
Marshall

Re: Timing Gear Replacement
 

Just one more question on this topic; if I have a clunk coming from this area, I believe it is the timing gear. Does it hurt to run the engine this way or will I just 'break down' and need a tow?

Thank you

Re: Timing Gear Replacement
 

A clunk in the timing gear is usually associated with a metal center timing gear that the metal has loosened from the fiber part. This condition requires replacement, and don't use a metal centered gear.

Re: Timing Gear Replacement
 

I appreciate your answer. So he tells me that the clunk is coming from that area but it is an aluminum gear (the engine on this car he purchased has only 2500 miles on it).

Is it possible that the clunk is a loose gear? Or some spring/plunger thing that Paul Shinn mentions on a video?

Thank you for kind responses.

Re: Timing Gear Replacement
 

Some fiber gears have an aluminum center. The fiber part and the aluminum center have been known to separate. If that happens the fiber part will get damaged and loose some teeth or suffer other damage. The gear can fail at any time and it is best to replace it before any additional driving. Most owners go with the aluminum gears which last a lot longer and are more reliable.

Removing the nut can be really difficult. I have resorted to cutting the gear in one place almost through with a Dremal cutoff wheel and then using a chisel to complete the cut. Others have used a chisel to turn the nut without cutting it. Buy a new gear with the hex nut so that a socket wrench can be used next time. You may have to buy a socket wrench because the size is large.

When using a cutoff wheel, stuff rags around the area so that the metal particles do not get into the engine and vacuum up all particles.

Re: Timing Gear Replacement
 

OK, I know a lot of people do this but the logic of it has always escaped me. You had to buy the tool for the stock nut, so you already have that tool. If you switch to the hex nut, you now have to buy a second tool, plus you have to buy the socket to fit it. Whereas the original tool can be used to install the stock nut just fine. Why not use the stock nut? If you're worried you won't be able to get it off, you can (a) use anti-seize and (b) not torque the dang thing to 100 ft-lbs, which is completely unnecessary anyway.

Re: Timing Gear Replacement
 

Measure the backlash. Should be in the .005" range, anything in the .009" or more will cause a rattle. The spring should add some tension against the gear, I usually shim it.

Re: Timing Gear Replacement
 

Gents - I used the impact wrench. First try nothing. Second try nothing. Third try the nut spun off, so easily I thought I dreamt it!!!

Thanks for the great advice.

Don

Re: Timing Gear Replacement
 

When using an impact wrench or air chisel, the compressor air pressure needs to be at least 90psi. I discovered this the other day with my new air hammer, trying to drive modern valve guides deeper into the engine block. At 70 psi, the guides wouldn't move. I was hesitant to increase the pressure over 90 psi - but I did. And that did the trick! I wonder if you had enough air pressure to back off the camshaft nut?
Marshall