No power at low RPM

[ekslee]

1969 280SL, automatic trans

Under 1,500 RPM - no power.  Sounds fine revving in Neutral, but putting in gear and trying to get moving causes severe "chugging" (don't know how else to describe).  Very difficult to get moving up a slight incline.  Downshifting to "2" lessens the problem.  It's easy to replicate the problem by pressing the gas and brake at the same time.  Once car is moving and RPMs get up to 1,500, everything seems to be fine. 

Recently blew the fuel pump fuse and replaced it.  Don't think that would have anything to do with the current problem, but thought I'd mention it.  Car runs fine at higher revs, I don't think there's anything wrong w/the pump, now. 

[ja17]

Hello,

What is the history of the problem?  Something recent? Did it come about all at once?

[ekslee]

Sorry, not really sure.  It's my Mom's car.  She's been complaining about it chugging and sputtering, but she's not very good at describing the symptoms.  After changing the fuel pump fuse (couple weeks ago), it seemed fine.  I'm sure it was having the problem, but I just didn't experience it.  It had some bad incidences on Mom's next drive, so she didn't drive it after that.  Next drive was the drive where I figured out what the symptoms were. 

[J. Huber]

I'd check the dwell and condition of points and plugs first.

[ekslee]

I'll do that.  Points and plugs are pretty new, but I'll check the ignition stuff, and let you know.  Wonder if it could be some timing/advance problem. 

[ja17]

If the car has not been exercised and has just been moved about, started and stopped, the new plugs can be fouled.

[ekslee]

Joe,
Good call.  I checked the plugs (OK), distributor cap and rotor (cleaned the crud off the cap contacts), and cleaned the points.  This made a significant difference.  Problem was still there, but quite a bit improved.

Then I remembered, "Oh yeah, I need to check the dwell."  It was waaay off - probably about 45 deg.  My vague recollection was that 28 deg was about right, but the dwell get really spastic below 30 deg, so I settled for 30 deg.  What a big difference!  Guess the dwell has been increasing gradually over some time.  Come to think of it, it has been a little harder starting, for a while. 

Thanks for the help!

[Benz Dr.]

It depends which distributor you have. If it's the aluminium one 30 degrees is perfect. If it's the cast iron version 38 - 40 would be what you need.