I had a visit with the long lost and lamented Brian Carlton a while back. He drove my SDL. Said it was pretty good but seemed to be a bit muted in the acceleration. he thinks it could be the timing is off owed to stretched timing chain. Said the fix is to put in a new one. Doesn't sound as easy as replacing a timing belt in my Bimmers, the 325i E30.

Anybody done it?

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1986 300SDL, 362K
1984 300D, 138K

It is an easy job. Remove valve cover, remove tensioner, tie wrap chain to cam sprocket to hold it into place, cut old chain, tie new chain to old roll engine using crank bolt cutting and adding tie wraps at cam sprocket as you go. Take your time and make sure chain STAYS attached to cam sprocket.

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Jim

How advisable is it to change the chain without changing the guides?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Before getting carried away... Have you checked timing chain "stretch"? I mean if the timing is good already and you replace the chain, you won't really be accomplishing anything right?

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Good point.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Usually, there is just slight wear (stretch) of the timing chain (say 4 deg at crank). That is easy to compensate with an offset key, which I did in both my 300D's. I even over-corrected slightly to account for future wear. The guides don't affect timing since they just keep the chain tight on the return side. If your chain was worn, the engine should give higher HP, since that occurs at high rpm. Racers setup valve timing delayed because at high rpm there is a time lag in air filling the cylinders so the valves should be lagged to match. Read-up on "variable valve timing" (VVT in tuner high-end Hondas) to understand. But stretch also delays fuel injection, i.e. "start of delivery".

Generally, one first sets the valve timing (offset key or new chain), then adjusts fuel timing by rotating the injection pump. For best power/mileage at expense of perhaps slightly rougher idle, many recommend setting 27 deg BTDC fuel timing, instead of the 24 deg spec (my 1984 & 85). I did so, but can't say I noticed a difference. I wouldn't put much stock in a "seat of pants" test. I suggest temporarily running a tube from the intake manifold to a boost gage in the cabin. If the turbo isn't giving boost, that will make a big difference in both torque and max HP. Good luck.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

No offset keys for a 603. They use an axial index pin rather than a Woodruff key.

Check chain elongation and IP timing. Nudge IP timing to the advanced side of spec range if throttle response matters. Make sure it matters because touching the IP means moving an o-ring that might be 30 years old. That’s a bear you don’t want to poke.

Doesn’t sound like Brian to suggest replacing the chain based on feel but I wasn’t there.

Sixto
98 E320s sedan and wagon

Based on BillGrissom's remarks he might have sensed something he didn't fully explain. He alluded to it saying thats mine start to feel some punch at 3000 plus RPM but that it was not real quick before that. He said one of his had a good bit more torque at the lower RPMs than mine.

But there's a lot of good advice here. I'll need to research this.

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1986 300SDL, 362K
1984 300D, 138K

I'd be more inclined to suspect lack of boost/fuel-enrichment. Prior to replacing the seals in my ALDA, mine was a complete turd below 2000, and really picked up after it hit 3000.

My ALDA was leaking badly enough that it made most sieves seem watertight. Resealing it results in the power coming on much smoother with full boost by 2K. It's like lighting a fire under it, seriously.

The timing chain "stretch" is so easy to check, you can do it in less than 10 minutes. If it's stretched beyond 2-3˚, replace the chain. If it isn't, don't lose any sleep over it.

If you have a leak in the ALDA circuit, or have a clog in the intake manifold nipple, you'll be slow to build boost until the pressure is adequate to overcome the clog or leak, then you'll build full boost as the fuel is enriched.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Great advice. On my '81 300SD, I did a small adjustment on the Alda which gave a noticeable power boost. Haven't touched this one but I'll research what you refer to and give it a look.

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1986 300SDL, 362K
1984 300D, 138K