George, I agree with both Mitch and Peter. Swap the vac lines at the distributor, reset timing at idle to 4 degrees ATDC, then check the timing at the high speed spec (4000rpm?) to ensure that retard, advance, and mechanical components of ignition timing are in spec. If the engine stills lags a bit on acceleration, or you want better mileage, you might disconnect & plug the retard line at the distributor. Next step, free up the manifold heat control valves under the carbs. Between the dwell measurement confusion related to the transistorized switch unit, constantly clogging idle jets, sticking manifold heat control valves, ignition timing complexity, and dash removal to replace broken control levers and expansion valve, I doubt I'll ever be tempted to own another vergasser. Wife, however, swears by her15 mpg 320ML, whle I've sworn at it the three times it had to be towed in, for broken, but operationally critical, plastic parts and clamps. Regards, Mike Boerner sdl, 300d, both 87s
If the advance was on full when you set the timing, it's probably doing exactly what I had assumed it was doing. From what Mike said, (and from the chart in the .pdf) it sounds like you did it right (if the car were working properly). The car is over 30 years old and likely gone through a few sets of vac hoses. Somebody may have misrouted hoses or replaced a fitting that was meant to include a delay valve, restrictor, etc (or such a fitting might be original but not functioning as it did when new). Do you have vacuum diagrams for it? It might be as simple as switching the advance and retard hoses on the distributor and resetting the timing. Mitch. -----------------------------------------------> > Message: 11 > Date: Sun, 14 Aug 2005 11:33:01 -0500 > From: Peter Frederick <[EMAIL PROTECTED]> > Subject: Re: [MBZ] 72 250 stalls at drive > To: Mercedes mailing list <[EMAIL PROTECTED]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=US-ASCII; format=flowed > > George: > > You have the lines hooked up backwards! > > Manifold vac on the retard diaphram all the time, ported (variable, > that is) vac on the advance. What you currently have will start out > with retarded timing and go later as the engine speeds up and the > "advance" switchover valve cuts in! You are in fact something like 12 > degrees later than it should be. > > Try 7 BTDC with no vac applied and see how it runs. > > Peter
