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'78 l28e cam and crank timing help


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Edit - First, thank you for any replies and to anyone who read my original post.  I am learning this with the FSM and two repair manuals.  I used a second set of eyes to go out and triple-check that I hadn't made a bunch of mistakes.  The first cylinder gets a compression reading on the gauge at about the 45 mark (if it existed).  When bringing the pulley mark to zero with the help from my second eyes, I get a completely different and much less dramatic looking scenario. 

 

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The timing mark on the chain is a V (sitting at 2) versus a shiny which I couldn't find before.  This looks less problematic than the crazy scenario I originally posted about but is still puzzling to me as the PO's mechanic didn't work on the timing but said there was a definite issue.  Do these markings look off to you?

Edited by newoldzguy
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Do the mechanics notes mention cam timing being severely retarded or ignition timing?    The picture of the pulley does not make it look like the engine is at TDC.

I agree with you.  I will go back out and verify again but this is where the compression test (finger over the 1 plug hole and a compression test guage) claims tdc is and I can see the cyclinder through the hole.  Is there any reason why the crank pulley mark would be so far off the mark (if it is at tdc)?

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The finger in the hole method is only to indicate whether the piston is on Compression or Exhaust stroke. 

 

Final step with the finger in the hole method is to stick a long thin screwdriver in the plug hole, and then slowly rotate the crank pulley by hand, until you feel the piston come all the way to TDC and then pause before heading back down. You can get it pretty dead nuts accurate like that.

 

If mark on pulley is still out, then it's possible that the dampner rubber ring has slipped or someone has put the wrong pulley on.

Edited by Chickenman
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The new picture of the pulley it looks much closer.  If this picture correlates to the oil pump drive shaft that also looks correct.   To check the V notch on the cam pulley you will have to remove the cam bolt (~100ft/lbs) to see the other notch.  It looks like someone has engraved a line perhaps to extend the hidden notch under the cam bolt.  If this is the case your cam is close although from that view it could be slightly off.  Tough to see from the camera angle.

 

The marks on the chain move around as the engine is turned.  So overtime the engine does a full rotation it will move it's place on the cam gear.  I think 4 turns and it will go back to it's original position.  These marks are meant for setup only, and not a good way to judge cam position once assembled.  This is what I have learned at least.  

Did you try checking your ignition timing with a timing light?  Could it not be possible the mechanic was talking about ignition timing (Although, i suspect he would change it on the spot).

 

Edited by HuD 91gt
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  • 2 weeks later...

I didn't want to mess around so I spent $12 on a piston stop from amazon.  I rotated it one direction until it stopped, and then rotated the engine the other direction until it stopped.  Right in the middle between the marks was my TDC.

 

Go on amazon and search for 

 

Competition Cams 4795 Top Dead Center Stop, 14mm Bolt-Style
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