Where is it written

[spstan]

Engine damage is very rare, especially with 75K miles. And especially since you drive it normally.

the chain tends to get looser as mileage goes up. This retards the cam timing so power goes down and it can make it heat up easier.

if your car is running smooth like EFI right now then the chain is in good/decent shape.

4; The car is running smoother than it ever has (may be due to the MSD distributor which replaced the Chrysler ignition module). Running so smooth I hate to mess with it. But reading some of these posts has put a fear in me. My race car neighbor told me if you replace the timing chain you should replace the cam shaft. Told me it was a 3 day job on his Nova.

Like I said before the car has been mostly babied but I think the next step is to remove the distributor cap and put a breaker bar on the crank to check the rotation. Paul

 

[Toolmanmike]

4; The car is running smoother than it ever has (may be due to the MSD distributor which replaced the Chrysler ignition module). Running so smooth I hate to mess with it. But reading some of these posts has put a fear in me.

Don't let it bother you, just turn the crank back and forth to check for the slop.

My race car neighbor told me if you replace the timing chain you should replace the cam shaft. Told me it was a 3 day job on his Nova.

Of course the cam is worn. Does it need replaced? Probably not. Especially if the engine is running smoothly. Old engines can be a can of worms if you let it.

Like I said before the car has been mostly babied but I think the next step is to remove the distributor cap and put a breaker bar on the crank to check the rotation. Paul

Yep, get that test done and report back.

 

[CBODY67]

First time I've ever heard that the cam and timing chain set need to be changed at the same time. Not even on a Chevy engine.

You can check for "play" in the timing chain, but that will NOT tell you anything about the condition of the nylon on the cam sprocket, if it is suspected it is still the OEM production sprocket.

Just some thoughts,
CBODY67

 

[57fury440]

You do not need to change the cam when replacing the timing chain and sprocket. If it took him 3 days to do that, then I would not take his advice too seriously.

 

[Triple Pickle]

Love thy neighbor. But, in your case ignore his advice.

 

[volksworld]

replacing the cam just cause you're doing the chain? that's insane especially if you're not doing the job yourself...adding the cam into the mix means (1) pulling the distributor and drive gear (2) pulling the intake manifold and valley pan (3) pulling valve covers (4) pulling rocker arms, pushrods and lifters ....now you have the dilemma of what cam grind to replace it with, what brand, who's lifters, will it need new valve springs, new valve seals...will you degree it or just slap it in? you need to break it in properly and even then there are tons of horror stories of todays crap cams and lifters going flat...and you might even wind up with an intake leak when you're done...sure if you're a hot rodder and want a hi performance cam it makes sense to do the chain at the same time...but not the other way around

 

[Dan Scully]

64 Buick 401 75,000 but almost 50 years old. New chain tighter than a hookers hold on a 100 bill.
Cheap insurance to replace it for me.

 

[Loadrunner]

where is it written that one has to replace a timing chain at between 80,000 and 120,000 miles? Finally got my 1975 NY'er running smooth (MSD distributor makes the car run like it is fuel injected - naturally this happens with only 2 months to go before winter).

Any way the car has around 78,000 miles and with smooth running accomplished the next thing I'm thinking is replacing timing chain. So I'm thinking if I drive gentle and change the oil every 2500 miles will this help preserve the timing chain? I mean is it written in stone that the timing chain will fail? Does any one have a story of a high mileage NY'er with the original timing chain? Paul

It isn't written anywhere, and some never fail.

My '70 W300 snow plow truck - like a whole winter of drag racing - has a 1980 Dodge Diplomat engine in it, and sprung a leak from the timing cover front seal a few years back, so I R&R'd the seal, which Chrysler in all their wisdom chose to trap behind the cover, and I found a nylon toothed timing belt inside in perfect condition, and this engine had the dog run out of it by a farmer down the road since 1980, and then my snow plowing for 10 years.

I did replace it with a Cloyes double roller, because that's how I roll, but it wasn't causing a problem after 30 some years on the job.

 

[Milo]

I have replaced many mopar timming chains and never once had to replace camshaft

 

[fury fan]

I had a timing chain jump at the gas station when I restarted the engine after a fill-up. Can happen anytime, anywhere.

If it's a car you plan on keeping, a Cloyes tru-roller is a nice piece to install.
Last time I did one it was a ~$100+ chain, and that was a long time ago.
But roll one of them in your hands vs a standard double-roller and the difference is very noticeable.