Zenith Carb Issue - What would you do? - Page 2 - PeachParts Mercedes-Benz Forum

Mint2Me · #16 06-25-2013, 07:30 AM

We drove the heck out of the Heckflosse this weekend and it performed great. Yesterday, a 95 degree day, I made a routine run to my mechanic's place to meet a friend who was expecting delivery of his old Mercedes. My car ran well for the first 12-15 miles and then I made a stop at Starbucks. After that 15 minute stop, it started to run crappy again. Slightly rough idle around 500 rpms. It stalled once at a traffic light. My mechanic drove it and we are scratching our heads again.

We pulled the plugs (NGKs) and 5 looked pretty much the same. The sixth looked brand new. Like it never fired...ever! We thought that might be a vacuum leak but we checked everywhere and couldn't find anything. We fooled around with the carbs again and got it idling smooth again but the proof is in the driving and it isn't as good as it was this past weekend. Not as bad as it was before but not right. Am I really going to be forced to get Webers?

Am I crazy to think it might be ignition related? We installed a Petronix and my mechanic says he checked the plug wires. I had a Morgan that acted up when it was hot and that turned out to be a coil.

JMela · #17 06-25-2013, 09:58 AM

Did you upgrade your coil when you installed Pertronix?

Mint2Me · #18 06-25-2013, 12:04 PM

Quote:

Originally Posted by JMela

Did you upgrade your coil when you installed Pertronix?

Yes we did. Going to change the plug wires with proper Mercedes Stuff.

tcb323 · #19 06-25-2013, 09:13 PM

you may have to clean out the fuel system completely and re line the tank . it may be bringing up tiny flakes of rust which clog the needle valves.

pedrocamp · #20 06-25-2013, 10:12 PM

As you mentioned it seems limited to one cylinder so either ignition or a valve adjuster came loose. Cylinder #6? Carb problems usually affect the 3.

Mint2Me · #21 06-26-2013, 07:16 AM

Quote:

Originally Posted by tcb323

you may have to clean out the fuel system completely and re line the tank . it may be bringing up tiny flakes of rust which clog the needle valves.

We think alike...it was the first thing we did. Relined the tank, blew out the lines, cleaned the carbs – twice. We have a new M-B fuel pump, fuel filter, Petronix ignition and coil. We are on our second set of plugs.

Mint2Me · #22 06-26-2013, 07:18 AM

Quote:

Originally Posted by pedrocamp

As you mentioned it seems limited to one cylinder so either ignition or a valve adjuster came loose. Cylinder #6? Carb problems usually affect the 3.

We adjusted the valves last week so I imagine they are good. They were awful and we should have done that earlier.

Ordered new plug wires from M-B CLassic Center. Should have them today or tomorrow.

ctaylor738 · #23 06-26-2013, 09:36 AM

What dwell readings are you getting? There have been problems with Pertronix having too little dwell, not giving the coil time to re-charge. This was reported on the Pagoda website.

Did you use a CO meter when you set the idle mixture? If so, 5-6% seems to be about right.

Mint2Me · #24 06-26-2013, 09:55 AM

Quote:

Originally Posted by ctaylor738

What dwell readings are you getting? There have been problems with Pertronix having too little dwell, not giving the coil time to re-charge. This was reported on the Pagoda website.

Did you use a CO meter when you set the idle mixture? If so, 5-6% seems to be about right.

That's a good one. We'll check that on Friday when I bring it in again...

Mint2Me · #25 07-02-2013, 08:08 AM

The new M-B Classic plug wires were fitted yesterday. I want to think it improved a bit but there is still that annoying slight stumble that occurs between 1800 and 2300 under load.

If I really full throttle it, there is no stumble and pulls right up to 5200+ without issue. So light throttle stumble, heavy throttle no. WHen should I just give up?

Coolvibes · #26 07-02-2013, 09:18 AM

You can give up after you die, but in the mean time try this. If there is a problem / difference with only one plug, then I would think the problem is not fuel related; maybe ignition.
Is the plug getting electricity? Is it firing (take it out the engine, but leave it connected to the spark plug wire while cranking the engine to test). Switch the plug to another cylinder; does it fire now. Is the spark plug wire good, even if it's new? Is the distributor cap OK (check the underside of it for signs of arching / damaged terminals)? Lastly, do a compression check on the cylinder in question if nothing else checked out. BTW, I have twin Webers on my 1967 W110 230 and they work great. Still have points, but would like to upgrade to Pertronix in the future.

Mint2Me · #27 07-11-2013, 07:33 AM

Another half day in the shop and it is worse than before. I have given up and ordered a Redline Weber kit. Stay tuned.

Adler · #28 07-13-2013, 07:02 AM

Once a 180 or 130 engine overheats badly the zenith's will likely warp and cause various starting and running faults which even a new kit will not rectify.
The warpage needs to be trued and rectified at the base and at the two parting surfaces . The upper part is diffiult to reface due to protusion of jet channels.
Adler

Mint2Me · #29 07-24-2013, 05:58 PM

Life is good. The Webers are on and the car has been reborn. The difference is night and day. More power, quieter and seemless acceleration.

pedrocamp · #30 07-25-2013, 07:17 AM

What did you think as far as the quality of the Redline kit? Linkage? Installation and connections? Tuning? Could you post an image of your install or is an update on your Mint2Me site? Looked but could not find.

Thanks.

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