(72 Bavaria) Timing chain slop help?

[Buffarea]

This is my first post here and hope no one minds a none-coupe post!
My Haynes or Chilton does not mention a seperate procedure for JUST tightening the chain, but heres why I ask.
How much play should there be in my timing chain? I adjusted the valves yesterday and while rotating the crank pulley back and forth noticed what I think is an alarming amount of play in the difference between how much the pulleys move before the cam OR distributor rotor move. I have never noticed a noise from the chain but the car runs eratically, going from powerless to fine, or dieseling after shut off.
I know there are still carb sync issues and I have not timed it with a light yet, but assumed those were the causes until now.
If you have had your valve cover off and rotated the engine, maybe you can share your experience and help me out.
Cheers, Michael

 

[m_thompson]

The timing chain tensioner is presurized from the engine oil. When the engine is not running there is only a spring for tension.

 

[Buffarea]

Yes! Thank you for that answer, it explains alot. I really didn't need another major setback on this project.
By the way, is my Bavaria presence on the coupe forums accepted, or should I keep quiet?
Thanks again

 

[x_atlas0]

Nah, you are fine, as the majority of the mechanicals work. Plus, many members own both.

If you are that concerned about the chain tension, you could replace your tensioner. It is a 5 min job, costs ~30$ for a new cylinder, spring, washer, and balance ball. If you aren't sure about the last time the job was done, I'd do it anyway. It really quieted down my coupe, that's for sure.

 

[61porsche]

timing chain

I've just installed a new chain yesterday and buttoning thing back up.

Here's what I know;

1) Is your timing erattic? A little or or a lot? Mine was slightly. I checked the tensioner, adjusted it to spec. It gave me a little more tension. I have carbs which I surmise gives a little more tendency to back fire. After rebuiliding the carbs, replacing every gasket that could have given a lean condition, tuning, valve adjustments, etc. I felt that the chain was next.
I have an original engine ( compression in spec, distributer like new, etc.)that I want to keep before I drop in something more serious.

The engine ran fine; but had a very slight miss that wouldn't go away. Noise wise at start up rarely would make noise. Sounded like plastic; not metal when you took off the oil filler cap. Something was definately amiss though when it happened.

2) From the manual- it looks in the illustrations that the tensioning rail is plastic and has a thickened end. It's not. Just a curved piece of metal with a hard rubber surface that the chain rides/ slips on. The chain guide is plastic.

3) With the top timing cover off, the timing guide was all the way towards the notch of the oil resevoir.

4) With a new chain- the timing guide was about halfway or at least 1/4" away from the notch/ wall internal of the housing. What this told me was that if the tang of the guide rail is all the way up against this wall or vertical piece of the oil resevoir which is necessary for the tensioner to work; there is no more adjustment for tension without replacing the chain.

5) Where the noise came from was that the chain was hitting the cover just slightly evidenced by wear marks. Nothing major, just annoying. It was metal; just aluminum.

I'm sure that there are many M30s out there where this isn't an issue for high miles; as many people would say that timing chain problems are rare. I also know of people who do replace M30 chains. I've read a lot of the posts out there for Zeniths and backfiring that I can't believe or won't accept that they came from Germany like that. For me, I just wanted it to run the way it was designed to work; so I changed mine. We'll see if it responds in a day or so when it's all together again.

To answer your question: Can you adjust the chain? NO. ( They just gradually grow at each link and there's 92 of them or something like that.) You can check everything on the adjuster against spec to see if you're in the ballpark. It can help; it did for me. The cure for me is a new chain and being able to know you can dependably run at will.

My question to the board- I have what appears to be an original engine, cast 71 ( corresponding to a 72 coupe) , 82 head w/ fuel pump opening. ( 2130797 on the pad above the starter) The damper has written on it in two places with yellow paint marker 3441 very deliberately. Is there a bore /stroke combo out there like this? :confused:


Best regards,

61Porsche

 

[Buffarea]

Preface: This car sat a year or so and was in disrepair upon my purchase:
The reason I started to question the timing chain is that the idle flucuated wildly ranging from around 2500 to a stall. But the good news is that after adjusting valves, a static timing adjustment and basic choke and idle settings to the Webers, and adding 2 engine-to-frame grounds, the car runs pretty darn well. Today I was able to dial in the timing with ye'ole strobe light and am gonna leave it well enough alone.
The timing chain does not make noise nor are there any where marks inside the cover, so I am going to assume the slop I noticed was due to the lack of oil pressure in the adjuster.
Thanks for the replies.