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hotratz
02-04-2007, 10:56 AM
Hello All.
I'm in the process of reviving a 304 that is in a 76 CJ5 that I recently adopted. Long story short, I found a bent push rod that eventually lead me to a very sloppy timing chain. It doesn't appear that it jumped a tooth but probably very close.

I'll come right out and admit this is my first AMC V8 so I can only compare it to the multitude of SBC that I'm more familure with. I was a little surprized to see that much slop in a timing chain on an engine with only 77K mile. (about 1" deflection)

I've heard of some oiling mods for this engine intended to improve oiling in the timing chain cover. One of these was to drill a small orfice into the middle of the oil galley plug behing the cam sprocket. I need to know if this would be benificial or a detriment to overall oil pressure further down the system.

In general, the rest of the components behind the timing cover appear to have had sufficient oiling.

Is this timing chain stretch for a 304 with 77K miles normal? Would additional oiling even matter?

jeepsr4ever
02-04-2007, 11:24 AM
I wouldnt be concerned too much about extra mods before I looked at the basics. Was your oil pump in good condition to begin with and what types of oil filters did you use. What weight of oil did you run.


Alot of engine damage can be traced back to a oil pump with excessive wear. The oil pump should be the primary concern. Beyond that one should look at adding a extra capacity oil pan and then you can look at other options like smaller hole cam bearings, smaller hole pushrods or rocker arms. All 3 with a new oil pump will give you too much pressure. Every engine has a combination and should be done right without sacrificing oil pressure down the road like the extra hole will do.

hotratz
02-04-2007, 11:42 AM
I've never taken this vehicle out of my driveway yet. It was given to me after sitting under a tarp for the last 14 years. The owner knew there was a mechanical issue with it but couldn't remember what it was due to a stroke he suffered some time back.

Anyway, When I got it home and did a compression check on it I found a dead #4 cylinder. All others were around 150 psi within about 4 lbs of each other. I replaced the bent push rod I found and now had about 146 psi in the once dead cylinder.
The oil pump must be in good condition because I was amazed at how much oil was being pumped up to the rockers as I was turing it over with the remote starter during the compression checks.

Like I mention before, everything else behind the timing cover looked like it was well oiled. The dist. and cam gears looked very good.

Sounds like I just need to replace the chain and sprocket set and be done with it ?? The cam sprocket is a nylon tooth type.
(never fond of those)
It had some chain impression in the teeth but not enough to account for the 1+ inch of deflection I found in the chain.

ironman_gq
02-04-2007, 06:05 PM
when you go to the parts store ask them for the "heavy duty" timing set. it costs more but it should be a double roller timing set. they're well worth the money and last much longer than the stock set.

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