Diesel RVs: [diesel_mercedes] Fuel Economy, Power & Cam Timing

Yes Mark, you did ;

The thing is : I'm not comfortable fooling with the OHC, I worry I'll screw it up or damage things .

I'm keenly aware that cam timing is critical and shuffle keys offer the solution .

The V-8 Hot Rodders did this all the time using dial indicators to make sure they had the timing perfect .

I have never done it .

-Nate

LIVE in the world as it is, WORK to make the world as it should be

Rob wrote :

Mark

Thanks for the reminder.

Cam timing is on my to-do list. I already bought a 4* offset key, so next time I get in there, I'll swap it out.

Rob

MARK wrote :

I've said years ago what the problem is, Nate. Cam timing. Anyone who's had to advance their Injection Pump timing has proven to themselves that their timing change has stretched. Setting the IP is doing only half the job. Now, both of you, check the position of the timing marks by setting the crankshaft at "0" with both of the valves at cylinder one closed, and see where the notch on the camshaft timing gear is in relation to the notch on the first camshaft bearing tower. The woodruff keys are available in one degree increments up to 5-degrees. They're available from autohausaz.com; part numbers are:

6219910067 - 5-degrees

6219910167 - 4-degrees

6219910267 - 3-degrees

6219910467 - 2-degrees

Make a guess as to the number of degrees it's off, then, get the off-set key, and install it such that the camshaft is now a bit clockwise from where it was originally. I wouldn't go any less than 3-degrees, maybe 4, as these engines with the mileages they've covered are going to be at least that much off. AND, having the camshaft a bit advanced doesn't hurt anything.

If you had to make a big adjustment to the IP to get it timed correctly (like 10-degrees? WOW!), you may want to first advance the camshaft gear a whole tooth on the chain, then recheck the position before installing the offset key, retarding the camshaft back to get it to the desired position.

If you think advancing the IP improved mileage and power, wait till you see what happens after you get the camshaft correct in relation to the crankshaft.

Mark in Centennial, CO

1979 300SD (27 mpg combined, with 4-degree offset camshaft timing key)