timing chain / bad dist cam gear

[cwiehle0]

Hi guys, have not posted here in a while, I'm in need of some advice. My jeep quit running, and I narrowed it down to a worn timing chain and that it jumped timing. I disassembled the front of the motor ('76 AMC 304 ) and found a bad dist cam gear. I had already bought a timing chain set but now that I see it wasn't that, should I replace it. It seems as though I would run less a risk of messing something up if I left the timing chain alone.
One thing that is confusing me, and giving me some apprehension is the manual is telling me to turn the cam gear to 3 oclock and count 20 teeth from the crank mark. Why do I have to do this? I was told to simply line up the two marks on the gears before removal and install the new gears in the same fashion with the marks lined up.
I checked the deflection (with a tape measure, so probably not 100% accurate) and it is within allowable tolerance, probably 1/16- 1/8" under the 7/8 total allowable.
Also keep in mind, this is my wifes mall crawler (sorry) and will never see a trail,offroad, or long trip.

So, in short, should I just replace the cam gear and reassemble?

 

[Bent]

I would replace the timing chain. You already have it apart and they run a lot better with a fresh timing chain.
I think you put the chain on with the marks lined up, then turn the crank (clock wise?) until the cam gear mark is at 3 o'clock and count the teeth. If you have twenty between the marks, you know you're not a tooth off. But, it's been a while since I've done one.

 

[Lumpy Grits]

Fix what's broke-first.
LG

 

[mtnwhlr]

I checked the deflection (with a tape measure, so probably not 100% accurate) and it is within allowable tolerance, probably 1/16- 1/8" under the 7/8 total allowable.

So, in short, should I just replace the cam gear and reassemble?

This sounds fine to me I would leave it alone. If it's not broke don't fix it.

Fix what's broke-first.
LG

 

[caveman]

If you decide to replace anything, replace it all. Timing chain and both gears. A half worn out chain or gear will wear the other parts faster. They all need to wear together.

 

[Hedgehog]

Generally I agree with the logic that says , "if it aint' broke don't fix it." In this case, where you are having trouble with at least one part of the system AND you are right there with parts in hand, why not? You will sleep better knowing you've freshened up the most troublesome area in an AMC engine.

While you are at it I'd replace the gear on your distributor. When I go my D.U.I. distributor the instructions highly recommended getting a matched set of cam/distributor gears, I think MSI was what they recommended. I'm sure someone will step up to advise using factory gears only, not a bad idea, but I believe that a set of matched gears are the way to go. Along with cheap insurance.