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A Cautionary Tale ...Tail

Outsider

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So I stepped up and bought a GTX a few months ago, haven't bought a fun car for over 30 years. This one is driver quality, a 25 year old plus fixer up and paint that was pretty much what I was looking.
One of the reasons I bought it besides it was decent appearing, was that it was a good runner with good, smooth power throughout. However, after I took possession, the more I drove it, the more I wondered if something wasn't quite right, as despite it being a factory exhaust manifold car with a magnum like cam, it seemed the power really didn't seem to come on until after 4k and then it wanted to go to the moon, which I was not interested in, since I didn't want to scatter it.

I decided to try some checks and tune exercises, including lighter dist springs to bring the advance in earlier and that helped some, but was not enough. So some time later one day after a couple hour drive and the near home requisite putting it through its paces, I hurt something as it lost some power and was making a metallic tinking noise. Got it home and started doing some checks. Pulled the modified distrib since it suspect since I had touched it, but it looked ok. However, while checking I noticed that when I was turning the crank with a socket and breaker bar the distrib was not moving in sync.

I started pulling it apart and this is what I found.
 
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Hopefully your valves are ok and it'll be a simple fix. Lighten up Kern.... my brain works faster than my typing, so I make mistakes too.
 
I understand a 50 year old car has likely gone through several owners and a lot of mods even though the car may not have that many miles driven. I'm guessing the motor was "freshened" some time ago, likely 10 or 20 years ago based on the age of the gaskets; with an overhaul gasket, bearing, timing chain kit. Unfortunately it was a standard kit, with a standard, though US made, timing chain, but that wasn't the main problem. When I got the timing cover off I could see the timing gear looked a little wonky and when I checked the cam bolt it was loose. After I took the chain and gears off I found the cam gear had been loose and the cam pin had worn through the back of the gear. Close inspection showed no evidence of any thread lock on the cam bolt.


So, its a bad news, ok news thing. After ordering a double roller timing chain, I decided I should keep on doing some checking and pulled the pan to check the bottom end for torques etc. Found forged pistons and balanced assembly. While it was running it never lost oil pressure, and I was keeping a close eye on the gauge after I noticed there was something wrong. After installing the new chain, bolt and an application of thread
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lock, I did a compression test and got 175 to 180 for all, so I called it worth moving on without pulling the heads. Got it back together and it runs good.
 
Think you were right on time finding that issue, that could have become a major disaster if not found.

Just to confirm i understand what happened, due to the cam gear bolt being loose the cam sprocket tilted and went that far it cam "off" the locator pin, allowing it to be out of sync with the crank, right?
Quite some cranking pressure btw.
 
Yes as best as I can tell, it came loose in phases. It appears it kind of hammered out a notch in the cam gear over considerable time, which I presume retarded the cam some, but it still ran well and made good power. Then recently I was hitting the throttle pretty hard close to home just after a completing a short trip, it slid out of the notch so much that it was not running well. Better to lucky than good sometimes. John
 
Wow good thing you got it before the valves met the pistons. Nothing good happens when that cam bolt starts backing out...we had that happen on a Roadrunner with a 400, just a factory-style rebuild, done by a popular and reputable builder. I personally won't use single-bolt cams anymore, and even with the three-bolts I put some blue loc-tite on just for a little extra help..
 
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hopefully it gives you many miles of fun!how bout a car pic? gotta love this place and GTX's!
Kern will be along soon to finish out the school year.hope the next lesson is application of the ignore feature for the reduction of blowby!
 
As requested pic of the Green Machine. Kind of a rainy day in these parts, so an inside pic.
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Ya, after I started racing in the 70s I always ran rollers and they had 3 bolts. I never really had time again for a street car w/1 bolt cams until now. I'll give this one a chance with the thread lock before I give up and buy new stuff, as it runs pretty good otherwise. Happy Motoring All
 
I was thinking you had a project, that thing is good to go! very nice!
 
Thanks BB, at this point in life not much time for many more projects. Forty years ago I had had several '68 and '69 cars, and parted a couple '71s, but had never had a '70, so I figured it was now or never. Not a contemporary "perfect" car, but a good complete driver quality car. If it was a new rotisserie restore I probably wouldn't want to drive it like I have. I still have my '65 Coronet too, but it hasn't been streetable since the mid '70s.
 
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