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Old 02-01-2001, 08:20 PM
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Join Date: Jan 2001
Location: Tucson, Arizona
Posts: 758
Greetings All,

Simply a quick question, hopefully not a quick answer so I can understand the impacts fully. I have a 1980 300TD with of course a 5 cyl. diesel. If the camshaft timing aligns at the top end but the crank, (harmonic balancer) timing is not at 0 TDC what is the effect on both sides of the spectrum, either retarded 10 degress or advanced 10 degrees ? Advanced I would imagine the valves would be bent or toast and if retarded by the same degree or more would cause what to happen? Also what impact would this have on the fuel injection pump, spay to soon, too lat or what?



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Old 02-02-2001, 07:25 AM
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Is this a rhetorical question?

You did not say that your cam timing is off, you are asking what would happen if it were off by ten degrees, is that correct?

If it's off by ten degrees, and the car has not been recently apart, most likely there is a severe and alarming amount of timing chain stretch. This would result in lower compression and a sluggish running engine. And would probably eventually result in a "hand grenaded" engine.

Timing chain stretch would result in a retarded camshaft. This means that when you turn the engine, on the compression stroke, to the TDC mark, the camshaft would not yet be to the point where it should be at TDC.

In the case of ten degrees advanced, the camshaft would reach this position before TDC. In this case you very well could be experiencing valve to piston contact. Not a good thing.

The injection pump is timed separately. You could have a stretched timing chain and still be able to time the pump correctly with relation to the crankshaft. If the chain has indeed stretched, the pump timing would be retarded, but not quite as much as the camshaft, because there are fewer links of the chain between the pump and the crankshaft, than there are between the cam and the crankshaft.

Have you already checked this, or what is your situation?

Good luck,
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Old 02-02-2001, 02:38 PM
Wm. Lewallen
Posts: n/a
Larry is right. If your timing is off 10 degrees,due to a worn chain,you need to install an offset Woodruff key on the camshaft. I experimented once with a 1967 200D and set the timing off by one chain link-(that's 18 degrees). The valves did not strike the pistons until a speed of about 50MPH. Luckily, no damage was done. I would not do that again. Use offset keys, or replace chain and cam gear.
Bill Lewallen Lexington,Ky.

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