Timing issue 75 280z

[zclocks]

I have a timing issue that I need help with.

 8 months ago I had my damper pulley rebuilt on my 75 280. I replaced the damper and everything was fine. I haven’t put the car on the street in several years , but start and let it run every couple of weeks.

So for months the motor would start and run fairly well. The motor always had a very small mis at idle and up to about 1500 rpm. This was unusual as I never have been able to get the motor to run as smooth as I wanted. I should also mention that the motor was totally rebuilt many years ago and only has about 50 miles on the clock.

I tried to start the car several days ago and it was hard to start, several back fires, very rough, and wouldn’t idle.  I realized it was a timing issue so I removed the valve cover with the intention of checking valves and timing.

To my surprise I found that the intake rocker on #5 cyl had jumped off the rocker guide. The adjustment nut was locked so the valve lash had not changed. I finally got the rocker back in place and set the # 1 cyl to TDC. In the past I understood that the lobe of the #1 cyl was to be pointing straight up at TDC.   

At TDC my cam lobe is at about 45 deg . I know it’s at TDC and I rotated the motor stopping on the timing mark to make sure that the piston was at TDC, also measured piston position, and both valves are closed. I checked the vale lash on all the valves and all were in speck (cold).  At this point I was worried about a valve problem with the #5 cylinder so I did a compression check on all cylinders, everything was good and no leak down.

I also checked the timing chain position and mine is #2 position and just slightly left of the notch. See photos for all the above.

Here are my questions:

-- Is the cam lobe on #1 cylinder supposed to straight up at TDC?

--Is there a possibility that the damper pulley key was severed and the damper pulley has rotated on the crank shaft?

--Why did the intake rocker on #5 cylinder jump off the rocker guide?

 

At this point I want to check all possible timing adjustments before I restart the motor. Any help will be very much appreciated.

Thanks…Ron

[Patcon]

I believe your cam lobes are correct for TDC

[kickstand80]

The lobes will look like bunny ears

 

[zclocks]

Thanks , that's what mine look like. Have you ever had a rocker come off the rocker guide?

[Zed Head]

These engines seem to throw rocker arms occasionally, especially if they've sat for a long time.  Maybe the valve guides are tight since they're new, or they're drying out as it sits.  Apparently today's detergent oils drain more fully than non-detergent.  (Obscure factoid I picked up somewhere).

But since it's open you migth as well check the wipe patterns.  Maybe they're off and a rocker arm pad caught an edge.  There have been some posts on the forum about bad wipe patterns causing a racket.

The notch is on the gear which is bolted to the camshaft.  I think that the only way the cam could be off is if the locating dowel was missing.

[siteunseen]

I agree, looks good.

I was breaking in my "just rebuilt" '77 and about 30 minutes from home I hear a terrible clicking from the head. Slowly back roaded it back home and found the same thing, a rocker had jumped off. Put it back on after asking the guys on here. Never had another problem.

[zclocks]

Thanks , that's what mine look like. Have you ever had a rocker come off the rocker guide?

[zclocks]

WOW, mine made a terrible noise that sounded like the chain tensioner let go! I would hate to be  driving down the FWY and throw a rocker.

 Thanks for the input.

[siteunseen]

41 minutes ago, zclocks said:

Thanks , that's what mine look like. Have you ever had a rocker come off the rocker guide?

I found the thread and I need to apologize. It was my lash pad or rocker guide that fell off the valve spring. The rocker actually stayed on top of the valve spring retainer it was just super loose but straight. Looking at your's I don't think you would have gone too far without damaging something. 

Mine...

 

 

[madkaw]

Probably the lack of use is the biggest culprit. Valve probably hung up and the rocker went off the rail. Worst thing you can do to these engines is to NOT use them. Just starting them up now and then is not enough.  I'd put it back on and go thrash on it down a back road .  

[cgsheen1]

He means, put it back on, recheck your valve lash, and go thrash it...

[zclocks]

I was surprised when you said you were 30 min from home and you drove your car with rocker off the pad. I could barley keep mine running. 

Yea, I know I should be driving the car, but work, health, and a lousy restorer are my only excuses. Things got so bad with the restorer I took the car back and had to do all of the mechanical and electrical work myself. 

My car had 368K miles on it when I decided to do a rolling resto which turned into a frame up. My goal is to get the old girl back on the road by December. I hate to admit it, but this is a 17 year old project !