'72 107 roller chains and rails
 

Hi Guys,
I'm real new here, so please bear with me. I've recently purchased a 1972 450-350??? sl and feel the need to replace the timing rails. It whines and grinds for about 30 seconds at startup, but is fine afterwards. Other than that, and not knowing much history of the car, and the horror stories I've heard about rail explosions ruining a $5000.00 engine, I feel that it's a good time to replace. It also smells really rich, like gas, but I'll save that for another post.
What parts do I need? Just two rails at $3.00 each? Are there any gaskets to replace? Any o-rings or seals? Should I change the tensioner wear pad? The last thing I need is to get knee deep into car parts and find out that I'm lacking a .15 cent widget with a three week lead time. I know about the puller for the pins and I have to take the alternator and stuff off the front. Should I take off the oil pressure tension plunger thingy and play with it in a bath of oil? I also have the bootleg disc from Ebay. ($30.00 including shipping, works great). Is this a good time to upgrade to a roller chain? Do I already have a roller chain? This isn't my daily driver, so I'm not pressed for time, but I would like to get it done before summer. My wife wants to go topless, and we need it to be dependable.

Thanks,
Bob.

How many miles?

I don't think the rails are the source of your noise, but I could be wrong. You more than likely need a timing chain and tensioner if over 100K and never been done. If you're over 350-400K you might need rails (upper and lower). The older cars have aluminum rails which don't wear out as fast as the plastic rails.

Might also need a valve adjustment while you're in there. Should be adjusting them every 15K or so on the 4.5 (same interval as the diesels).

Do a valve adjust, and check your rails and chain stretch while your there, also change the plastic ends on the oil pipes.
You can check chain stretch by setting the crank on t.d.c. then look for a mark on the first cam tower and then a mark on the washer on the cam on the back side of the gear, you can line up the marks and read the amount of stretch from the timming marks on the harmonic balancer. With the valve covers off you can see the wear on the top rails. I think there is a revised tensioner for that engine, about $35.
Jerryb

Miles and parts
 

Thanks for the help and advice guys,

The sl has 180,729 miles on it. I'm not sure when the last adjustment was done.
To do this, I'm guessing just like any other car, I'll need valve cover gaskets, and should do it when cold. Do I need a special MB tool or just a combination wrench and a screwdriver?

Bob.

Takes a special tool, although I've heard of it being done with a 17mm crowsfoot (but have heard that more offten than not the crowsfoot breaks). You need the Hazet # 2770-4, 17mm valve adjustment tool - about $68-$70 or so. Might try Phil at PartsShop/FastLane and see if he can obtain one, if not try Baum Tools at Baum Tools .