Timing Chain Stretch mercedes 450 slc
 

HI All,

I am taking out my engine and transmission out of my 1977 Mercedes 450 SLC.

the reason is to change the transmission. however whilst it is out will be good to do some general maintenance.

After turning motor to check timing marks. When Both cams are aligned on the timing marks, the crank pulley is about 6 degrees past Zero.

Is It necessary to change the timing chain ?

I will change the upper guides.

The cams look in generally good condition,

your suggestions is appreciated.

regards
C

6 degrees is a little long. 7 degrees for sure means change it. it's cheap insurance now so replace it and the tensioner along with the 4 guides. good luck, chuck.

Thanks

any thoughts on using a 5 degree offset?

thanks
c

At 6 degrees you've lost low end torque , definitely do new chain the engine will run smoother

at 6 degrees, the chain has weakened and stretched. install the offset keys, the chain continues to stretch until it breaks. that's why at 100k or so, i add time to an lof to pull the valve covers and check chain stretch. they break at about 125-130k, depending. don't chance it. good luck, chuck.

Thanks all for your suggestions. I will follow them.

I have a question, more form a curiosity point of view.

What are the camshaft numbers for the Mercedes 450 slc.

will any camshaft from a w126 fit into the 450 slc?

thanks
c

HI All
I checked the camshaft numbers for the 450 SLC using a mirror.

the left side(US driver side) is 00 and the right side(US passenger side) is 71.

Can anyone confirm that this is the standard ones ?

collin

Check that the "71" is not actually "01". 00/01 are a pair, and correct for your engine.
70/71 are a pair, but with much shorter timing.

Thank you Frank

I checked the rear stamp on the crank shaft a couple of times and it is 71 T. It could be that the previous owner changed only one cam out.

this would surely affect the performance?

if I am unable to find a pair of 01/00 cams, what other pair would be a good substitute for the 450 SLC.

thanks
C

The 02/03 profiles are the only ones that are even close to the 00/01.

thanks Frank and forum

so, I am sure the previous owner had a bad camshaft on the right bank and replaced it with a camshaft( number 71) possible forma W126 , 380 model.

I am looking for a set of cams with the numbers 00/01 in the meantime.

The question I have, will a set or 70/71 be a workable solution if I replaced both cams with this option.

I also have a set of 08/09 cams. any thoughts on using these alternative sets to the 00/01. will it affect performance negatively?

if the answer is " do not use them" , then I will find a set of 00/01.

appreciate your comments.

C

Use the 08/09 pair, advanced 6 deg. These will still be quite a bit shorter than the 00/01 pair (13 deg @ intake, 20 deg @ exh.) Torque will be better, power reduced.

70/71 were used in M116, and have less lift than cams for the M117.

thanks Frank

what does shorter mean.

overall would u recommend the use of 08/09 or would u rather suggest that I find the correct 00/01 cams?

thanks
c

"Shorter" means less duration, i.e., valve open time in degrees of crankshaft rotation. In this case the intake valve would be open for 13 degrees less with the 08/09 profile than with the 00/01 profile (179 deg vs. 192 deg), and the exhaust valve would be open for 20 degrees less (175 vs. 195).

If you have the 08/09 pair, I would go with them. If you find some 00/01s make a judgement based on price.

I don't know if it makes a difference, but Africa XJ6 is in Africa. He most likely has a ROW or Euro 4.5L SLC. Are the cam specs for those cars same as those in NA?

By the way, the weak point on the chain systems are the plastic guides. Chain will hardly ever fail, but the guides will and jam the chain.

Another thought - would new sprockets take up that 6deg? Only ask because when I installed new chain on my 72 (metal guides!) I still had some offset. Thinking I perhaps should replace sprockets (160k miles)