Timing and crank puzzle?

[mjr45]

OK I know I have a bad timing issue, the engine runs like crap over 2500 RPM. New timing chain, guides and head was redone. Now when #1 is at TDC(by touch with a stick in the cylinder) lobes on the cam look like rabbit ears, the timing mark on the crank is at 15° and the woodruff keyway is at about 11 o'clock. I have a rebuilt crank pulley to put on since I think maybe the balancer spun, but why would the keyway be that far off from 12 o'clock if # 1 is at TDC?

[zKars]

My guess is that the timing chain was not timed correctly between cam and crank. With crank key way at 12:00, check if the #1 cam gear mark is close to its oval mark on the plate behind the gear.

Edited June 12, 2013 by zKars

[Zed Head]

15 degrees of crankshaft rotation won't drop the piston very much from TDC. Up and down motion of the piston drops dramatically at the top and bottom of the crankshaft rotation. That's why they call it DEAD center, it has to be exactly centered to be at the top. You can't do that with a stick.

What you really need to do is actually measure timing with a timing light to know if your timing is off. Why assume when you can measure and know for sure? There could be many other reasons for it to run bad at or above 2500 RPM.

p.s. if you set the timing mark to zero where is the woodruff key located?

Edited June 12, 2013 by Zed Head

[Wade Nelson]

I'm thinking you should swap cams with the guy here who's Z engine will ONLY run ABOVE 4000 rpm....

/snark

[mjr45]

When I checked the timing with a light it was at about 20 degree's but when I initially installed the engine the timing was at 7-8 degrees, since I had no more room for changing the timing on the dizzy, I left it there over a couple of weeks the timing changed as stated. Right now I am in the process of removing the crank pulley and will re-install the timing chain which has less than 500 miles on it and make sure everything is in alignment per specs.

Wade I'll check the timing mark on the cam when I pull it all off. Like the cam remark, maybe between us we'd have 1 good engine.

Zed, with the key at 12, the cam is off the rabbit ears config. which makes me believe the cam and crank timing are off, I'm actually surprised it ran at all.

Edited June 12, 2013 by mjr45

[Zed Head]

I don't know enough to know if the keyway should be straight up when the timing mark is supposed to be at zero (TDC). But, if I was in your spot I would take the other damper that you have and compare its keyway to the one on the engine. If they're in the same spot, a change won't help.

It wasn't clear that you are trying to restart an engine that you just put back together. Is that what's going on? I've never heard of a timing chain on an L6 actually jumping a tooth although it does get proposed often. Putting it together wrong is a possibility of course.

Good luck with it.

[mjr45]

Zed, this engine was running, although very poorly, when I was checking the timing which I do fairly regularly and noted that the timing had changed from 7 degree's to 20 with no adjustment done. The keyway should be at 12 o'clock with the timing mark at zero, so I'm thinking that the cam and crank timing are off and that the damper has failed.

[EuroDat]

You think your front pulley slipped. I had that happen and found TDC by measuring the nr1 piston depth. The "stick" method it too ball park figure for checking timing.

To find TDC accuratly I punched the guts out of an old spark plug and welded a section of rond steel (section of 8mm bolt shank) into it. Fit it in nr1 spark plug and gently turn engine by hand until the piston touches it.

Mark the pulley and then remove the plug. Turn the engine past TDC and fit plug agaiin.

Turn engine backwards until it touches plug and mark the pulley.

Exactly in the middle between these two marks is TDC.

Then you can check timing.

Chas

Edited June 12, 2013 by EuroDat

[mjr45]

Thanks Chas, I'll try that today. It is my understanding that when the crank keyway is at 12 o'clock, the dizzy rotor just past the clip and the cam with #1 cylinder lobes at about 10 and 2 then # 1 is at TDC. I gently used a screwdriver as well as a stick and felt the piston going up and down and stopped turning the crank at the top of the stroke. Should be at TDC or very close. At this time I've got stuff apart with no oil or coolant and I'm going to pull the crank pulley and just realign the timing chain and put the redone pulley on which will hopefully allow me to time it correctly.

Edited June 12, 2013 by mjr45

[mjr45]

Sometimes I feel like a complete idiot! After putting the timing mark at zero degree's the keyway looked like it was at about 11 o'clock, then after looking some more I suddenly remembered that with the engine in the car it is canted to the side, thus putting the keyway at 12 o'clock. I'm still going to pull the timing cover and reset the chain, just to make sure it's all lined up correctly, also after pulling the dizzy, it was no where near the correct position, the #1 plug was at least 1 plug off the dizzy cover mark. Oh well, live and learn.

[Jeff G 78]

Wait. Cam timing and ignition timing are two different things. Don't pull it apart yet! It sounds like your distributor drive is off one tooth. To fix this, you need to set the engine to #1 TDC and pull the distributor body. Look at the shaft. It should look like the hands of a clock at 11:25. If it isn't, you need to drop the oil pump and rotate the shaft. There is a mark on the oil pump and a mark on the shaft. Line those up and slide it in. It will rotate slightly as the gears mesh. Put one oil pump bolt in and go up top to look at the orientation again. It could take several tries to get it right.

[mjr45]

Thanks Jeff, but I wanted to make absolutely sure the cam and crank were right, which I now know they were, also, I had to replace my crank pulley with a newly refurbed one. Today I'll be putting it all back and will make sure the dizzy is correct. I've also learned that the timing cover doesn't go back on without dropping the oil pan, last time I did this, the engine was on a stand much easier that way, in the car its a PITA.