progress report...how set points gap? - Page 2 - PeachParts Mercedes-Benz Forum

ggenovez · #16 10-01-2006, 08:01 PM

Sounds like your carbs are out of sync.

Do you have a carb sync tool? if not you can try with a vacuum hose down the carb throat and listen for the different sounds and adjust as needed. I would not recommend if it's backfiring through the carb though...

Neubie · #17 10-01-2006, 11:08 PM

At the end of the day, I got it to idle nicely right about 950 rpm (although with the air filter on, didnt want to idle, had to adjust the idle screws up a bit.) Got the dwell set to about 39, and the timing at about 25 btdc @ 1500 rpm. Timing light malfunction was operator error. Hissing sound was a break in a vaccuum? line? bout 1/4" id plastic yellow tube runs from exh. manifold round back of engine. Taped it up and seems to be ok. new fuel filter just for kicks.

She still stalls under load,i.e in gear. There is weak spark in cyls 2 & 4. didnt replace points, still couldnt figure out how to get them off.

Things to do this week.....any advice would be appreciated. I never would have got even this far without y'all Thanks for sharing your wisdom!

Marc

Neubie · #18 10-01-2006, 11:18 PM

Synch tool is on order, have done the trick with the hose. not sure what Im listening for, just trying to get the sounds similar in intensity. Adjusting with the idle screws and mixture screws to try and make that happen. correct?

t walgamuth · #19 10-02-2006, 12:23 AM

before trying to synchronize your carbs you need to get all other problems ironed out. til you know the carbs are clean and functioning correctly and the ignition is correct and you have no vacuum leaks you shouldnt touch your carbs. if you do you will probably get them so out of whack you will be in real trouble.

first check for vac leaks. replace any suspect vac tubing. on old hoses it often cracks right at the connection and is easy to miss. check for proper spark at all cylinders too. check for accelerator pump function too, and look to see if the carb is delivering fuel when appropriate.

only after making certain everything is working correctly should you touch any adjusting devices on the carburators.

good luck.

carburators are a pain but not really complicated in principal. in detail they are really complicated, if you tear them apart.

tom w

ggenovez · #20 10-02-2006, 12:54 AM

Ok. so if the spark is weak in 2 cylinders that means the coil is ok. the points are ok. There may be a problem with the cap on the distributor, the wire or the plug. See if the problem follows the plug and wire by swapping them with Cyl #3. If they do you might want to check the plugs and wires individualy.

Now for the sync you need to listen for the difference in sound. Adjustment is done by the 10mm linkage. Like Tom said, that's last.

Stalling in gear is usualy a vacuum leak. Take a fire exstinguisher and some carb cleaner and spray around the manifolds, carburator base, the 2 vacuum lines from the carbs and there should also bee a vacuum line for the brake booster and one that runs from the manifold around the engine bay and is used for AC or auto door locks and such. I would just plug the AC/door for testing purposes.

What color are your plugs? black to rich. white too lean brown just right ...

Neubie · #21 10-03-2006, 12:52 AM

plugs were just replaced, but old ones were white. good idea on swapping wires. I just changed the distributor cap as well so that should be in good order. What am I looking for when I spray the carb cleaner? I poured some lacquer thinner down the barrels tonight and let them soak a bit. noticed some seeping out the rear carb base, right between theupper insultating plate and the sheild on the front of carb.

Remedy for leak is tightening down the carb? are these screws fairly obvious? Do I have to take off the top of the carb to get to them?

Will look at this all tomorrow and report back,

Thanks!!
Marc

ggenovez · #22 10-03-2006, 01:36 AM

White plugs are indicative of running lean. Great way to need a replacement engine. Try turning your mixture screws a little rich (out)

When you spray carb cleaner or WD-40 around, while the engine is running, if you have a vacuum leak it will get sucked into the engine and change the RPM's. It will cause your RPM's to rise but any change you get is worth respraying and double checking.

Remedy for leaky carbs is a rebuild kit. You might want to try the screws on top of the carb but they are usualy very tight. Don't crack your carb by putting too much preasure and work in a star pattern.

Not sure what soaking the throats in laquer thinner will do. All the mechanisms that need cleaning are internal.

MercyBenz63 · #23 10-04-2006, 03:33 PM

Nuebie,

Before you go screwing with the carbs make sure your ignition system is working perfectly as these two items are closely linked diagnostically.

Your ignition trouble sounds to me like a bad condenser. This can cause periodic weak spark as well as backfiring. Also, you mention that it runs fine for a few minutes then dies, this is very typical of a condenser failure. The condenser (for non-transistorized ignitions) is the little cylinder screwed to the side of the distributor, these are cheap <$10.

The carbeurator trouble for your car is infamous. The weights/flaps on the exhaust manifold riser get stuck open heating the carb excessively eventually warping the carb top plate and body. Tightening the screws in this case tends to make things worse. Carb needs rebuild where the flatness of the mating surfaces is checked.

Good luck!