Just when I thought I understood A timing...

Synchro909 said:
This thread won't die!!!
There is something else that has been bothering me about Art's pictures in post #1. In the first pic, the piston is at (or close to ) TDC, yet the exhaust valve is open. That shouldn't happen till the piston is near the bottom of its stroke, a whole half a turn from where is it in the pic and certainly a lot more than either 3 or 4 teeth. Am I missing something or is there more?:eek:
Not that this explains the open valve but if the marked tooth on the crank gear is out in relation to the key, who is to say that it is out by a whole number of teeth. The key could have been cut, say, 3 1/2 teeth out. That might explain the 3-4 teeth issue.
Another (but unlikely) issue that hasn't been mentioned is "Is the key slot cut in the right place in the crankshaft?"
As they say, the thlot pickens!
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Actually the exhaust valve should close a few degrees after TDC, but with the cam gear being late by 4 teeth this is how the exhaust valve would be.
 
When the marks on the gears are aligned #1 is not supposed to be TDC on compression.
That only happens when the pin thru the hole in the timing cover is in the detent on the gear. Agree with Art and Vince and Dick
 
OK, I found my new crank gear and took a picture of both sides. It actually does make a slight difference if the gear is installed backwards. If backwards the cam timing will be retarded by a couple degrees.
in the correct position the right side of the keyway will line up with the top left of the tooth. When it's flipped over, the right side of the keyway will line up with the right side of the groove on the left of the tooth.

Both sides of the gear have a slight recess from the teeth, and the back side is a few thousands more recessed.

I just went back to page 4 and looked again at the corrected timing to see how it compared to my left picture, and I agree with Vince that it looks correct, so button it up and run it.
 

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Thanks for going to that effort Tom. My plan is to remove the pulley if it isn't too difficult to get off. I have the correct size socket for the nut but no longer have any 3/4 " drive breaker bars. I'll line one up and give it a try. If there is a mark way down under the slinger, that's a stupid place to put it. The gear is probably pretty hard material but I'll try to use a drill. It'd be nice to have the pulley off so I could clean it up.
 
Art Newland said:
Thanks for going to that effort Tom. My plan is to remove the pulley if it isn't too difficult to get off. I have the correct size socket for the nut but no longer have any 3/4 " drive breaker bars. I'll line one up and give it a try. If there is a mark way down under the slinger, that's a stupid place to put it. The gear is probably pretty hard material but I'll try to use a drill. It'd be nice to have the pulley off so I could clean it up.
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Looks like you got it right, why not just mark it with out taking the pulley off. Or just forget the mark.
 
forever4 said:
You guys are talking exhaust stroke. The timing marks only can go one way, and the ignition timing is done at the end of #1 compression stroke. Both valves are to be closed at #1 TDC ignition timing.

Art has it all timed correctly now.
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I was talking compression stroke but I think Tom was on exhaust stroke. Not apples with apples. I agree that Art seems to have it right now. It'll run fine.
 
I've got a 3/4" drive breaker bar now, I'll try to remove the pulley. If it's too tough to remove I'll just put it together, put it on the stand and see if it'll run! (how exciting!):)
(( yes this is the real Art ))
 
Art Newland said:
I've got a 3/4" drive breaker bar now, I'll try to remove the pulley. If it's too tough to remove I'll just put it together, put it on the stand and see if it'll run! (how exciting!):)
(( yes this is the real Art ))
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Art,
You are welcome to use my air impact wrench (600 ft lbs of torque). It will spin it right off.
 
Art Newland said:
I've got a 3/4" drive breaker bar now, I'll try to remove the pulley. If it's too tough to remove I'll just put it together, put it on the stand and see if it'll run! (how exciting!):)
(( yes this is the real Art ))
Click to expand...

Apologies for the confusion, Art.
 
easy does it, theoretically that nut shouldn't be on there that tight......

there are threads where guys have sheared the shaft.....that is a large 1 3/8 (IIRC) nut attached to a threaded shaft.....basically to give a very large bolt.

put the impact on low and let it vibrate some
 
Well, apparently all of Vince's replies have an expiration date, and they have all expired.
Once again they're all gone. :confused:

Now we have another mystery to solve. :D
 
I could have used this posting a couple weeks ago when I replaced mine. My gear was not marked correctly as the "dimple" was for the timing pin, not the gear alignment with the crank gear. Set it to TDC, and then insert the gear making sure your timing pin lines up with both valves closed and the distributor rotor pointed to cylinder number 1 on the cap.
Kevin
 
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