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Old 08-02-2017, 11:32 PM   #1
'63MurderTruck
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327 Compression Test - Results

I've got a long thread here about the problems that I'm having with my son's 327...

I think I've found the problem, and now need some advice...

Here are the results of the compression test(dry):

1 = 35(***UPDATE*** Now it's 105)
2 = 125
3 = 125
4 = 120
5 = 122
6 = 110
7 = 122
8 = 128

So, the number one cylinder is the culprit.

My question is... what should I do now?

I'm going to pull the valve cover off and inspect the rocker arm and valve spring, as well as the valve lash on number one. Anything else that I need to check?

Please keep in mind that I'm a novice...

Thanks

Last edited by '63MurderTruck; 08-03-2017 at 05:08 AM.
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Old 08-02-2017, 11:52 PM   #2
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Re: 327 Compression Test - Results

***UPDATE***

okay, one of the rocker arms bolts had almost completely backed off. The rocker arm itself wasn't even on the push rod.

Any ideas why this bolt may have backed off? Any suggestions on preventing it from backing off in the future?

Thanks
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Old 08-02-2017, 11:53 PM   #3
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Re: 327 Compression Test - Results

Might describe what the perceived problems are. I imagine a miss...
Has it been running well, and this is a new problem?
Has the engine been running or is this a recent start of a dormant engine?

Just WAGs...

(posted before seeing the above reply)
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Old 08-03-2017, 12:10 AM   #4
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Re: 327 Compression Test - Results

***UPDATE***

I've messed with the valve lash, the best that I can get out of number one is 105psi.

Will that be okay? Please keep in mind that this is a daily driver for a 18yr old, not a pro-street... lol
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Old 08-03-2017, 12:20 AM   #5
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Re: 327 Compression Test - Results

Sometimes a rocker arm stud can pull upward out of the head. Usually if this happens you can see a clean ring around the base of it where it used to be in the head. Sometimes a pushrod can wear out at the top and it will get all eaten up at the tip by the rocker arm. Those are a couple of the more simple reasons that a rocker will loosen without the actual nut backing off.
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Old 08-03-2017, 02:02 AM   #6
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Re: 327 Compression Test - Results

Quote:
Originally Posted by '63MurderTruck View Post
***UPDATE***

I've messed with the valve lash, the best that I can get out of number one is 105psi.

Will that be okay? Please keep in mind that this is a daily driver for a 18yr old, not a pro-street... lol
Run it and check it again. Pour a can of SeaFoam in the tank when it gets below 1/4 tank and see if that dont help clean things up in an other wise non firing cylinder...Did the stud pull out? Maybe a worn rocker fulcrum and nut? In any case, make the necessary repairs and run it...
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Old 08-03-2017, 02:28 AM   #7
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Re: 327 Compression Test - Results

Stud seems fine. For some reason the nut "backed off"

Will do on the Seafoam .


Quote:
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Run it and check it again. Pour a can of SeaFoam in the tank when it gets below 1/4 tank and see if that dont help clean things up in an other wise non firing cylinder...Did the stud pull out? Maybe a worn rocker fulcrum and nut? In any case, make the necessary repairs and run it...
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Old 08-03-2017, 03:07 PM   #8
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Re: 327 Compression Test - Results

***UPDATE***

Okay, I did the Seafoam down the carb to clean the possible carbon build up on the valves.

It runs "ok" at about 55-60mph, BUT... it spits and sputters at lower RPM range 1000-1500RPM... AND... it won't idle in gear, it dies.

I'm gonna check the compression on #1 again, and mess with the timing, although I've already messed with the timing a LOT, and it never seems to fix this issue.
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Old 08-03-2017, 05:23 PM   #9
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Re: 327 Compression Test - Results

***UPDATE***

Just checked the compression on #1 again... with the butterflies open.

Dry = 110
Wet = 150

Now when it's idling after a test drive, it starts out idling at 1,000 RPM... then after about 10 seconds drops to 900... then 10 more seconds down to 800... it continues this downward RPM drop until it dies. Strange.

While driving it runs extremely rough at low RPM's. It accelerates good, and runs good down the road at 55-60MPH.
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Old 08-03-2017, 05:46 PM   #10
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Re: 327 Compression Test - Results

***UPDATE***

Vacuum Test:

Okay, I have to set the idle at around 1,200RPM in order to keep it running long enough to check the Vacuum...

It sporadically, randomly, and slowly fluctuates between 14 and 16 @ 1,200RPM. When I rev it - it goes down to ZERO, then up to a little over 20... then back down to 14-16.

I'm a novice but I think this indicates a Vacuum leak. What is the best way to track it down? I've tried spraying starter fluid, but no luck.

Thanks
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Old 08-03-2017, 06:23 PM   #11
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Re: 327 Compression Test - Results

No, that test shows it's normal.
A low reading would indicate a leak.
What's your initial timing?

And after reading your other thread, it still looks like you need a fuel regulator.

And your strange dropping idle is another indication of too much fuel pressure.

Last edited by geezer#99; 08-03-2017 at 07:41 PM.
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Old 08-03-2017, 06:44 PM   #12
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Re: 327 Compression Test - Results

Also check the mechanical advance in the distributor....if the weights are worn and sloppy or the springs are broken, the timing will jump all over the place....put a timing light on it and watch what it does...
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Old 08-03-2017, 07:41 PM   #13
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Re: 327 Compression Test - Results

***UPDATE***

Not sure exactly which one of the many things that I tried worked, but it's running GREAT now. LOL

Thanks everyone!
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Old 08-05-2017, 03:45 AM   #14
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Quote:
Originally Posted by '63MurderTruck View Post
***UPDATE***

okay, one of the rocker arms bolts had almost completely backed off. The rocker arm itself wasn't even on the push rod.

Any ideas why this bolt may have backed off? Any suggestions on preventing it from backing off in the future?

Thanks
Yes. The stock style nut is swedged (pinched) to help it lock in place and should not be re-used. If it backed off once, it will again.

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Old 08-08-2017, 11:51 AM   #15
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Re: 327 Compression Test - Results

What he said.

Quote:
Originally Posted by GRX View Post
Yes. The stock style nut is swedged (pinched) to help it lock in place and should not be re-used. If it backed off once, it will again.

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