Originally Posted by Phil_F_NM (Post 3495819)

Ok folks, so gmog220d (Greg) helped me out a ton the other day. We got a few things sussed out: oil change, valve adjustment, checking timing with the 2mm method, pulling out my cam gear to see the offset key and were finally left with the question of what is a #18 camshaft? More specifically, we couldn't find the cam timing specs for the #18 camshaft, which is what my engine has on it. From the tag on the block, it looks like it is a Mercedes-Benz rebuild.

Things I thought I knew before working at Greg's shop:
-The timing chain was stretched about 5 degrees using the camshaft notch/tower notch against the crank.
-The IP definitely needs timing.

After the work:
-I have a camshaft with 18 stamped in the back.
-18 is not listed for cam timing specs.
-Against the 2mm valve test, my crankshaft balancer reads 16~17 degrees.
-Cam gear wear is very minimal. Teeth look good. Chain looks good.
-I have what we think is a 2deg offset key installed right now.
-My IP was missing the overflow banjo bolt/drain tube.
-I really should replace my front main seal...

Now, do any of you folks with the super secret Mercedes knowledge have the timing specs on that #18 camshaft?

Thanks all!

Phil Forrest

Originally Posted by Phil_F_NM (Post 3514314)

Greg, thnaks for telling me the answer was in my thread, today.
I haven't checked this thread in over a month as Bethanne and I have been moving then moving then moving again (landlord, et al difficulties.)
Anyway, back in July on the 15th we were in an area withzero cell reception and hadn't gotten our internet set up so I just didn't see the reply.
Anyway, thanks Stretch and funola!
I've decided since I'm pretty broke, just moved into a new place, saving up for a second set of wheels for some snow tires, saqving up for snow tires and having to get my main camera shutter replaced, I'm going to take the risk of sticking in an offset key and praying I get at least through the winter. The chain wasn't badly worn, the gear teeth looked good, so I should be ok. I also figure if something catastrophic is going to happen, it's going to happen. Ouch. Yes, the new chain is a bit of extra insurance but it's 10X the price of a key and quite a bit more work.
We'll get the key in there, time the IP then I'll get that linkage readjusted for altitude.

Then I'm going to attempt to use this car as my winter vehicle up in the northern New Mexico mountains. It's al we've got and it's all we can afford. She's made it so far through some really bad winters all across the country, I think she can handle it.

Thanks all!
Phil Forrest

Originally Posted by BillGrissom (Post 3492336)

Re racing, I would think retarding the valve timing would give more power at high rpm, since that is true in gasoline engines, and it is the same issue of getting max air charge into the cylinder. Gas engine "timing sets" often have 3 or 7 keyways so one can pick an advance or retard from the "straight up" design. Advance gives better low rpm performance (torque) and mileage. Drag racers go w/ the retarded settings. They don't care about low rpm because they rev the engines at the starting line and release the brake, or slam the tranny in (sometimes explodes). I had a friend who drag raced a Pinto and would retard the timing (rubber belt) one tooth before racing.

Re an offset Woodruff key, I see no issue using one as long as the chain isn't so worn that the teeth aren't meshing correctly. If you ever fooled with bicycles, you know you need a new chain when it only contacts the first teeth and is slack behind. Too worn and the chain starts skipping on the front sprocket. Otherwise, there is already plenty of slack in the timing chain, so as long as the tensioner can keep it tight on the return side, there should be no problem.

I am fooling with this currently, and trying to get a good measurement with my dial indicator. Last time I checked my 1984, it had 2 deg crank retard, which is the factory 10,000 mi wear-in spec, but I recall using the marks to measure that (inexact). I replaced my tensioner chain because the original was riding cocked (contact circles ~1/2 off) and the rubber liner appeared hard & cracked when I removed it.

Originally Posted by gmog220d (Post 3514372)

...
Why are the specified ranges so much larger for this group of cams?

Originally Posted by gmog220d (Post 3514372)

...

Stretch, I am curious to hear more about how the smaller offset keys don't actually adjust how we want them to. When I went through this on the '74 the cam timing was behind the outer spec by about 3.5 degrees at the crank. I installed the 2 degree (at cam) key and it brought cam timing up about 4 degrees (at crank), to just within the specified range.