350 sl 107 valve timing 5 degrees retarded. is this a big deal ?

[dagwill]

i was not happy with the performance or economy 20 ltr/100 [or is this about right? ] so i started checking everything ignition and total advance seemed fine mixture was good so i checked the valve timing  with the inlet valve open 2 mm
the timing on 5 6 7 8 was spot on but when checking 1 2 3 4 that bank was 5 degrees late . i was told that the timing chain had been replaced not long before i bought the car 5,000 ks ago
can anybody tell me is that one bank running 5 deg out worth worrying about

[John Skene]

Normally 5 degrees retarded would mean you have to set the idle speed higher to stop hesitation on starting off, plus your power and fuel consumption would be badly effected - however having one bank correct timed is probably masking this effect.

How many teeth are there on the cam drive sprocket? 5 degrees would be 2 teeth on a 36 tooth sprocket, or is this simplifying it too much?.

[dagwill]

john thanks, but a 36 tooth sprocket = 10deg/tooth  now thats at the camshaft ,remember the engine does two revs for every one of the cam so 10deg cam =20degrees on the crank
as the valve timing is measured at the crank ie with inlet valve open 2mm the crank should be at 4deg BTDC
so 5 deg equates to 1/4 of a tooth so i dont recon its one tooth out or anything
now i believe i can get offset woodruff keys and can remedy the prob
i was interested in how much [roughly] you thuought this prob would effect performance and ecconemy
thamks

[John Skene]

Dagwill, thank goodness you didn't act on my post which I wrote just before going out, and I did not check after arriving home rather late from the CMC meeting! It's 4.36am and the thought just came to me (it actually woke me up!) that I had messed up so I rushed out to correct it straight away - only to find that you realised I gave you the wrong information! There are offset woodruff keys to do the job. The 5 degrees is within the limits set by Mercedes before correction, but how much one bank being 5 deg out of timing will actually effect the performance I shall leave up to others.

[Greg]

Dagwill,

5 degrees late (at the crank) on the right bank is nothing to be worried about on an M116 or 117. I have seen them up around 12 to 14 degrees before any signs of noises suggesting the need for a new chain. The real risk when the chain gets that worn is chain slap before the oil pressure rises for the tensioner when starting. Chain slap against old and brittle guide rails (made of plastic) can break the rails which then get caught between the chain and sprockets. The result is the chain jumps or breaks and pistons hit valves.

20 litres per 100km is quite normal for an early V8 107 in traffic, especially if there are numerous cold starts or spirited driving. When my 350SLC was my daily driver I used to see 22 l/100 in Sydney traffic. An interstate highway trip would only bring it down to around 14 l/100 and even trying hard on an economy run would only see a best of around 10 l/100. These engines were fuel injected for performance, not economy.

Greg

[dagwill]

 Thanks greg very informative info on the valve timing i wont worry about it unless i have do something else to the motor and put an offset woodruff key in while ive got  it dismantled  THANKS
economy still makes me wonder 20ltr/100 with sedate country driving
It does seem to rev more than it should before any forward motion starts    could the torque converter not be transfering power as it should?

[OzC36]

20ltr/100? I suspect something very wrong with your car. I don't know what the factor spec is for your model, but this sounds far too high?

[adytum]

Would I be following the old KISS addage to far if I said to check the transmission oil.
Low oil level will create hesitation when starting off, also presure will not be up for torque converter to perform.
Worth a look.
Keep It Simple S.
Tony
 

[Greg]

Thanks greg very informative info on the valve timing i wont worry about it unless i have do something else to the motor and put an offset woodruff key in while ive got  it dismantled  THANKS
economy still makes me wonder 20ltr/100 with sedate country driving
It does seem to rev more than it should before any forward motion starts    could the torque converter not be transfering power as it should?

20 l/100km is not normal for country driving. I would suspect that it is either running much too rich or there is a fuel leak. I can't imagine a few degrees of valve timing or even ignition timing could have that sort of impact. A 350SL should return around 20 l/100km in heavy suburban traffic with short runs. Country driving should return something more like 14 l/100km.

Greg