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Old 06-05-2010, 10:34 AM   #15
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Can't set timing due to no marks

I went out to check the timing on my 454 this afternoon, and the strobe light could not find the mark on the harmonic balancer even after I verified the strobe was connected to cylinder number one's spark plug wire.

The only work done up until this point was to pull & clean the rotor and check the cap for cracks. Both the rotor and distributor cap only go on one way, so I don't think I screwed up anything there. The truck fired right up afterwards.

Out of curiosity, the strobe's inductive pickup was moved from wire to wire until the timing mark was finally visible after connecting to cylinder seven's wire. This cylinder is six cylinders away in the CW firing order (1 8 4 3 6 5 7 2).

Everything was fine two years ago when the timing was last checked.

The harmonic balancer looks okay and does not appear loose in its mounting.

If I were to trust what is lighting up while connected to plug #7, the timing is off two degrees.

Would anyone care to offer insight into what has happened?

Thanks,
Tom
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Old 06-05-2010, 01:20 PM   #16
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Would anyone care to offer insight into what has happened?

Thanks,
Tom
What could have happened is the weight on the balancer has shifted. It is also possible there is a second set of timing marks you may have forgotten about since the last time you checked the timing. There may be a second timing mark on the bottom of the engine that would align the mark with #1 cylinder.
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Old 06-05-2010, 01:35 PM   #17
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What could have happened is the weight on the balancer has shifted.
I wondered about that. But to shift that much, I figured there would be some evidence. The strobe lighting up almost within spec on a different cylinder, though has me stumped.

Quote:
...It is also possible there is a second set of timing marks you may have forgotten about since the last time you checked the timing. There may be a second timing mark on the bottom of the engine that would align the mark with #1 cylinder.
I wondered about that too. Nope - I sanded, chalked, and fondled the balancer's perimeter with no discovery.

Checking the timing was supposed to be the easy step in verifying I might have had bad gas on a previous trip, and not a burnt valve.

Ain't nothing ever easy these days...

Tom
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Old 06-05-2010, 02:28 PM   #18
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Tom,
Since you checked that the plug wires are indeed in the new cap in the correct firing order, the only thing I can think is that the balancer is bad and the rubber has let the outside spin. A couple of things you can do. First mark on the outer case the position of the #1 lead and then take the cap off the distributor. Bump the engine till the rotor is pointed to the #1 lead. This should be close enough and then check and see where the mark is on the balancer. If the wires are right and the rotor is pointed to the #1 terminal then the timing mark should be visible close to the pointer on the block. The most accurate way it to find true TDC is with a piston stop but I have used the shade tree method with a dowel stick through the spark plug hole on the compression stroke. Takes a big breaker bar to rotate the engine and it is much easier with all the plugs out. PUt your finger over the #1 hole and rotate till you get pressure indicating the compression stroke and then insert a clean rod to rest on the top of the piston to see when you get to TDC. Make sure it is on the compression stroke. I don't know with the angle of the plugs on the 454 heads if that is possible to use that trick, but I have used the dowel trick on everything from old jeeps to a Continental 0-470 in a Cessna. The easy way is the rotor on the distributor method. I'd bet your balancer is toast.
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Old 06-05-2010, 03:04 PM   #19
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Perhaps the balancer HAS moved in a mysterious way. But

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Originally Posted by 68 TWind View Post
...I'd bet your balancer is toast.
My first thought too.

I just can't get over how doggone close cylinder #7 times to what I expected to find on cylinder #1.

Perhaps during tomorrow morning's sermon, the resolution will present itself to me.

Tom
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Old 06-05-2010, 03:37 PM   #20
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Just some more possibilties.

Hi, are you sure you are on #7 wire? Are you using in inductive type timing light? Are you connected at the number one wire at the number one plug? Or are you at the distributor cap area. I have seen people install the distributor incorrectly and rotate the plug wires to make it work. Did you disconnect the number one plug wire at both ends and check for continuity? Chevies are known to have the timing marks on both sides of the timing chain cover, [different applications] could you have a left hand mark and be using a right hand marked dampner? Or vise versa, correct dampner and wrong timing chain cover.
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Old 06-05-2010, 05:07 PM   #21
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I too fall in the advance the timing till it pings and the retard it till it stops camp. An old hot rod technique.

Another old trick only applies to a known good balancer, something to consider if you replace. Scribe or paint a line from the inside of the balancer to the outside, crossing the rubber dampening material. That way you can verify that the outside of the balancer has moved or not. Unfortunately, that doesn't do you much good now.
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Old 06-09-2010, 04:26 AM   #22
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Oh for an easy solution

I ended up burying my head in the sand on the timing issue, and moved on to replacing the driveshaft carrier bearing. The next step appears to be removing and inspecting the harmonic balancer.



In the above image, it looks okay to me. Am I looking for the right signs of trouble?

Tom
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Old 06-09-2010, 10:40 PM   #23
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Hi, in your picture the harmonic balancer looks good; One that has slipped usually shows lots of cracks in the rubber isolator, or the parts are out of alignment. I don't see that. I would try to find, physical, top dead center. Then see if the timing marks line up. Don't get me wrong, but even if it looks good, it still could have slipped.
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Old 06-10-2010, 04:15 AM   #24
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Quote:
Originally Posted by overlander63 View Post
What could have happened is the weight on the balancer has shifted...
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Originally Posted by ROBERTSUNRUS
...but even if it looks good, it still could have slipped.
I used to think the harmonic balancer was pretty sturdy. But, come to find out, new ones are readily available at chain-parts stores, and there is even a place in Oregon who will rebuild my Suburban's existing one. So harmonic balancer failure is apparently not that rare.

I'll let you know Saturday how the Mighty Burb's harmonic balancer compares to a new one.

Tom
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Old 06-12-2010, 04:06 AM   #25
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In conclusion

Although all signs pointed to a shifted harmonic balancer, I still had doubts about mine because it was stiff, and looked okay. But after comparison to a new one, I knew the problem had been found. Look at the timing marks with respect to the woodruff key slots in the image below:



The outer ring on the oiginal equipment shifted over 135 degrees.

The new HB has a nice feature the old one did not have - the opening bore had been increased a thousandth or two to make it easier to install.



Thanks, everyone, for your help.

Tom
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Old 06-12-2010, 01:00 PM   #26
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Wow Tom,

That's quit a shift! That photo really tells the whole story, doesn't it?

Now make the mark across the rubber from the inside to the outside. I've seen a cold chisel used for that too. Support both sides and give it just enough of a hit to put a small line across that will still show through the paint.

Glad you figured out the problem and shared for everyone.
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Old 06-13-2010, 04:34 PM   #27
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I ended up burying my head in the sand on the timing issue, and moved on to replacing the driveshaft carrier bearing. The next step appears to be removing and inspecting the harmonic balancer.



In the above image, it looks okay to me. Am I looking for the right signs of trouble?

Tom
This photo of the timing mark guide is great, you wouldn't believe how hard it is to find one. In that photo of the marker it looks like you have it advanced to 16 degrees? Am I rigHt in reading that and is that what it should be set to?
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Old 06-13-2010, 04:48 PM   #28
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Picture is for general illustration only

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... Am I rigHt in reading that and is that what it should be set to?
No.

That is a "static" picture taken after the motor was switched off.

The spec on my '84 454's timing is 4 degrees BTDC.

Tom
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