Timing Gear Troubles

[tiap]

94 E250 4.9L efi Was cruising up I 95 at around 60 mph, looked down at the vacuum gauge and it was running a little low for no load. Seemed to have a little less power than normal. Van backfired a couple times and quit, would turn over, but not start, had it towed to the shop. Guessed it was probably the electric fuel pump. Fuel pressure checked out at 60psi cranking. No spark, here’s what I found. Pulled dist cap, rotor not turning. Dist gear gone on one side. Checked cam gear with mirror, looked OK, but the cam moved back and forth about ¼”. Thought the thrust plate bolts had probably backed out or the plate had broken somehow. Pulled cover and cam gear fell off when I tried to turn crank. Teeth on both gears in perfect shape. Didn’t think this was possible, no damage at all to cover. Surprisingly, it ran pretty well, even though this had to take some time to happen. Think I’ll go back with a steel cam gear instead of the alum hub fiber gear.

[F-250 restorer]

Wow, go to Vegas, because you're riding a lucky wave. I've seen kits with the keeper, etc. I think I saw it on Summit or headbolts.com. Now I understand why you posted a notice to mich the front of a cam.

Def. go with an all steel gear. Cloyes has a nice set, aluminum cam gear with steel crank gear, for iirc about $90.

I've heard of the luck of the Irish, but this is the luck of the 300. I lost the keepers from one valve on the freeway, and the valve did not drop into the cylinder!

Btw, use locktite on the cam retaining bolts. And I'd ck that cam end REALLY well b/f risking reuse.

[f100jim]

Wow. I cannot see any way that the bore in that cam gear could have "grown". That gear must have been wrong from day one. How many miles did it go before it gave up?

[AbandonedBronco]

That's extremely fortunate! I agree with Jim, it seems like it's probably always been like that and has just plain old held on for a lot longer than it should have.

If you need the cam key, this site has it:

Ford 240 300 4.9 liter 6 cylinder engines Cylinder head bolts / fasteners

The cam key comes in a kit with the crank key, thrust plate bolts, cam shaft spacer ring, etc.
You can also get a new thrust plate there as well.

[tiap]

I rebuilt the engine about 8 or 9 years ago. No idea of the mileage because the van was struck by lightning and knocked out the speedo.
Everything was new except for the rods and dist, but the gear would have looked good at the time.
The cam gear did press on properly at the time. I'm also baffled as to what would cause this, it obviously loosened and got worse over time. The thrust plate is perfect.

About 6 months ago, it started running very poorly and after testing everything, I found the timing out about 10 to 15°. I reset it and went on since it ran well again. It puzzled me that electronic dist changed at all by itself. It must have skipped a tooth then. It should have been my clue at the time, but I had never had any problems with dist gears.

Hopefully the lifters and lobes haven't suffered too much from the cam slamming back and forth 1/4".

[AbandonedBronco]

The cam in my '84 had a similar problem. The bolts that held the cam in didn't have loc-tite on them, so they backed out, so the thrust plate was loose. The only thing that held the cam in place was the timing cover.
So, it was able to move back and forth a good 1/4" or so. I noticed it due to the odd growling sound that would come and go from the front of the engine for no apparent reason (ended up being the cam rubbing against the cover and then moving away.)

After tightening it back down, I've since had the oil pan off to replace the gasket, and very closely visually inspected all the lobes and lifters to see if there was any ill-effects from the cam wandering. They all looked brand new. If that comforts you any.

[AbandonedBronco]

I'm curious, is the 1.250" diameter of the cam snout the correct measurement?
Which is wrong? The internal diameter of the cam gear, or the external diameter of the cam end?

[tiap]

I posted that question over on the other forum but never got an answer, so I really don't know. The snout doesn't look like it's worn and I tried the good part of the old key in the keyway and it's good. Hopefully just the alum hub took all the wear. I ordered an iron cam gear, so I'll see how the fit is. I was even considering drilling the cam/gear joint after the gear install and either pinning or tapping and threading and installing a flush allen screw to prevent any movement.

[Rogue_Wulff]

Ummmm, wow. I've never seen a cam walk inside a "press fit" gear like that....
Is there a "freeze plug" type cam plug in the back of the block? Been too long, I can't recall.
If there is a cam plug, it should be checked. Would hate for that to be about ready to fall out...................

[tiap]

Finally got all the parts and put it together.
The new steel cam gear measured .249" giving .001 interference on the snout. Sounded good, but didn't press on nearly as tight as the new crank gear.
So I drilled, tapped and put in a 5/8" long 1/4-20 set screw with locktite.
I didn't want this to loosen like the alum hubbed one.

I put a slot in the lower land of the dist gear to squirt extra oil on the dist/cam gears. Old trick with chevys, so I thought it would help here too.
Also put a squirter hole in the lifter galley plug to add oil to the cam /crank gear.
I'm using a high volume pump, so I should have plenty of flow elsewhere too. I brushed molyd oil on all the gears first.
As you can tell I'm a firm believer in lots of oil.








Here's an old trick for finding tdc on the firing stroke when working by yourself.
Gut a old spark plug and solder or braze an air fitting to it. Buy a pack of water balloons for a buck and when rotating the engine by hand the balloon will temporarily fill when coming up on No 1 compression for firing. Then continue rotating by hand until the timing marks are where you like them. Only hand tight is necessary for the adapter.





The engine fired up right away, couldn't find my timing lite, so I set it with a vacuum gauge until I find it. Ran it for about 15 minutes at a high idle.
Engine runs much, much better now, like it used to when I first put it together. Could set a glass of water on the valve cover and not have it ripple, it idles so smoothly. The last few months after the gears jumped the first time, it sounded like I had a rod banging, but that's gone now.
Steel gears are a bit noisier and at a higher rpm almost sound like a cheezy blower, sort of cool.

Hopefully the cam will stay put now.

[critterf1]

That "set screw" should do the trick.