I think I have stripped timing gear UPDATE

[Lawson Cox]

I know I am going to have to remove the hood, grill, radiator and timing cover. Then what else do I have to remove to replace gear? Don't know if it is aluminum or fiber.
1939 flathead in 35 pickup. Can't find anything on search. I have never replaced one.

[Ken/Alabama]

If your lucky that 39 engine has been rebuilt sometime during the last 75 yrs and someone installed a cam with a bolt on gear. The first thing I would do is remove the timing cover and take a look. If it is a bolt on half the work is done.. If its a press on its a lot more involved. Hardest part is getting to old one off. I have a homemade driver for installing the new one but you must have lots of room in front of the engine to drive it on. Or you can pull the heads,intake and remove the entire valve train then slide the cam out so it can be done under a press.

[jimTN]

All depends on if you have adjustable lifters. If so you can raise the valve as high as you canget it, pull the lifter up and stick a nail in the lifter slot and let the valve back down against the nail. I believ you can do that with a stock lifter, the early ones had diagnal slots, that is if you aim to use the same cam. That is the good thing about the adjustable lifters, you can change cams with them proped up. By all means get rid of a fiber timing gear if that is what you have. They are trash!

[Lawson Cox]

Originally Posted by Ken/Alabama

If your lucky that 39 engine has been rebuilt sometime during the last 75 yrs and someone installed a cam with a bolt on gear. The first thing I would do is remove the timing cover and take a look. If it is a bolt on half the work is done.. If its a press on its a lot more involved. Hardest part is getting to old one off. I have a homemade driver for installing the new one but you must have lots of room in front of the engine to drive it on. Or you can pull the heads,intake and remove the entire valve train then slide the cam out so it can be done under a press.

Thanks Ken. The engine is a fairly recent rebuild but not sure which gear was used. Not sure if it has adjustable lifters either.

[Walt Dupont--Me.]

You say you think you have a stripped gear. Remove the dist caps and spin the engine and see if the rotor is turning. Walt

[V12Bill]

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I had that same problem with my 1948 Lincoln. When I rebuilt the engine, I had access to a new cam, but it was the press on gear type Everything was fine until 5 years later the fiber gears wore out and the engine stopped dead. I got a metal press on gear from a large truck and every thing was fine after that.
PS I had to remove the cam to get the gear on. There were tools made to replace the gear without removing the cam though back in the day.

[Lawson Cox]

Originally Posted by Walt Dupont--Me.

You say you think you have a stripped gear. Remove the dist caps and spin the engine and see if the rotor is turning. Walt

Good idea. I'll do that. Thanks

[Flat Tire]

If you have a fiber press-on timing gear, often you can replace it without removing the camshaft. Pull the radiator, remove the distributor and timing gear cover, and cut off the old gear using a coal chisel or other instrument of destruction of your choosing. Mike the camshaft diameter to be sure you don't need an undersized timing gear.

Then heat the center steel ring of the new fiber timing gear to about 250 deg. F and it should slip right on the end of the camshaft, being careful to align the timing marks. However, if it doesn't slip on easily, have handy a big hammer and a piece of steel pipe with an I.D. slightly larger than the camshaft end and carefully beat the timing gear on. Make sure the center ring on the timing gear still is hot when you try the hammer trick or you'll damage the rear thrust bearing.

I used this method on my '34 and it worked fine and may work on yours. I hear that pulling the camshaft isn't any fun.

[Lawson Cox]

Originally Posted by Walt Dupont--Me.

You say you think you have a stripped gear. Remove the dist caps and spin the engine and see if the rotor is turning. Walt

I have pulled the cap (Crab distributor) and checked the rotor and it is turning as it should, with no hesitations. The cap looks good with no spark lines between the contacts. The rotor seems fine as well. I did find one spark wire loose, however, that should not be the reason for the back fire through the carb should it? It may account for a slight skip, but not a backfire. This makes me think the timing gear is probably okay. I guess it could have slipped a little, but that should cause tracks shouldn't it ????

This still has me scratching my head and other parts of my anatomy.

All other opinions readily appreciated.

[Brendan]

is power getting to your coil? do you have the right amount of voltage?

[51 MERC-CT]

Originally Posted by Lawson Cox

The rotor seems fine as well. I did find one spark wire loose, however, that should not be the reason for the back fire through the carb should it? It may account for a slight skip, but not a backfire. ??

This still has me scratching my head and other parts of my anatomy.

All other opinions readily appreciated.

Surprising that you didn't mention the backfiring to begin with.
Could be something as simple as cross firing between bad plug wires

[Lawson Cox]

Originally Posted by Brendan

is power getting to your coil? do you have the right amount of voltage?

Oh yes, it is getting fire or it wouldn't backfire.


And yes 51 MERC-CT, I thought I had mentioned the backfiring through carb but I see I had not mentioned that. Old Timers disease and all that.

All new plug wiring maybe 2 years ago but it has not been driven all that much since then.

[Marv]

Try replacing the Condenser.

[V8COOPMAN]

Backfire thru carb USUALLY happens when an INTAKE valve is open, and the cylinder fires. Sounds like a crossfire from another plug wire firing the cylinder with valve open for it's own normal intake cycle, or there's an intake valve not closing tightly, or even stuck open. Simple compression test would rule-out problem with intake valve. DD

[Talkwrench]

sounds like it wont be anything major Lawson.. Fingers crossed!

[Lawson Cox]

Originally Posted by V8COOPMAN

Backfire thru carb USUALLY happens when an INTAKE valve is open, and the cylinder fires. Sounds like a crossfire from another plug wire firing the cylinder with valve open for it's own normal intake cycle, or there's an intake valve not closing tightly, or even stuck open. Simple compression test would rule-out problem with intake valve. DD

Compression checks out within normal limits. All valves seem to be free and none stuck.

[Lawson Cox]

Originally Posted by Talkwrench

sounds like it wont be anything major Lawson.. Fingers crossed!

I sure hope so. I would hate to have to pull everything off to check for stripped timing gear, etc.

[Walt Dupont--Me.]

The next move. You haven't mentioned. Remove the spark plugs, prop the throttle open, take compression test. You may have a stuck intake valve ect. If the comp is all the same 100-120 the valve is not the problem. Posably a broken valve spring, unlikely. Let us know Walt

[G.M.]

Give it the MMO treatment. G.M.

[Lawson Cox]

Walt and George. I've done all that except checking for broken valve spring. That seems unlikely as all valves seem to be opening and closing properly from what I can see through the plug holes.

I am thinking about bumping the engine and distributor shaft and see if there seems to be any excess play in the timing gear by gently wiggling the shaft to see if there is any excess movement. Do you see any problems with that?