Stromberg 175 CD on '76 230.4 - H.E.L.P.

[arkie]

Last Wednesday I picked up a pretty nice 1976 230.4 with a Pierburg (Stromberg) 175 CD carburetor. It has been driving me NUTS - when I got it all of the vacuum ports on the carburetor didn't have hoses on them, the water mass for the choke system was missing, and the thing idled way too fast. I found some nice information on the carburetor - it seems that Pierburg took the 175 CD design over in the early 80's - don't know how it made it onto my car, though. I found a 75 230 in the junkyard and pulled the complete carburetor off - and started stripping parts off of it and getting everything hooked up as it should be and got the idle set down to proper levels. Everything seemed to be improving until tonight. The car has been running way too rich, so I started dissecting the parts carb to see how the "choke" mechanism worked. I took it apart and found everything gummed up, so I cleaned it including cleaning the enrichment jet so that is doesn't stick anymore. I found the same problem on the carb on the car (enrichment jet stuck in the depressed warmup mode) , so I just took that entire choke housing and installed it on my carb. The car was running pretty good for a while (maybe 15 minutes)as it was idling, then it started misfiring a little. The car was running very smooth before now, and it just isn't idling as good as it was. I have cleaned the rotor and put a new distributor cap on it in the last few days - I am waiting on plug wires to come in. I cleaned the points with a piece of paper (and they were clean), but I don't have any information on the gap in the points to check it. Maybe the ignition needs going through, or maybe I have the mixture messed up now that the carb is getting straightened out. Any suggestions or thoughts appreciated.

[nachi11744]

Hello,
You are on the right track, if the throttle spindle is not worn excessively causing an air leak, it may just need the mixture reset. Search for user name *oreo*, I have listed a webpage with the Pierburg service sheet in one of the posts.
Have a good week.

[arkie]

I installed new plugs and wires - the idle smoothed out and the miss at idle is all but gone. Now the big problem - when I drive the car it cuts out at higher rpms. If you depress the accelerator too hard, the engine starts chugging, choking, and spitting until you let off the gas. If you keep the pedal depressed, it will actually lose speed and black smoke bellows out the back. I have a new fuel filter for the car (the old filter has a little rust in it) thinking the engine may be starving for fuel under load, but I don't know why that would cause it to blow a BIG cloud of black smoke. One thing I haven't yet done is put oil in the carburetor. I have read that it acts as an accelerator pump - would it being out of oil cause this (remember - the choke needle was stuck in "rich" mode before I cleaned it up and freed its movement)?

[psfred]

That stromberg is a variable venturi carb, and it will run very funny without damping oil in it -- the venturi piston gets stuck and the mixture is all over the map. Holly 2700 seris carbs are similar.

Definitely get some damping oil in there.

Beyond that, I'm out of my depth -- the recommendation I've usually heard is to get a weber conversion kit and ditch the Stromberg, it's too much trouble.

Peter

[nachi11744]

Hello,
You need to fill the piston rod cavity with ATF and roadtest There is the remote possibility that the choke could be reengaging in low vacuum(full throttle)operation
My experience with the 175CD carbs has been with Volvos(manual choke) and Mercedes(auto choke) and I have to say that most, if not all, of the problems in the Mercedes application are centered around the automatic choke I have disabled the choke on my W115 200(it is in the tropics)and have had no further issues with carburation
The only other thing that can cause black smoke on acceleration is a blocked air filter, when more airflow is needed, a clogged filter will restrict it and cause black smoke. I see it all the time in restored or resurrected cars that have been sitting with the same filter for 30+years
Hope that helps.

[Oreo]

Hi

1) The difference between having oil the damper will not be as dramatic as you described. But eliminate that possibility anyway.

2) What about vacuum leaks? Did you over compensate for a vacuum leak with too rich an idle mixture? Whatever you do for idle will apply across the rpm range. So if idle is too rich, the rest of the rpms will be too. Big leak culprits are vacuum hose and booster (I encountered both).

3) Did you reset the float level? When fuel bowl level was too low, stumbling and cutting out will happen. It will idle but it can't accelerate.

Oreo

[67fintail230s]

With reguards to your lack of power and big black cloud... I had the same symptoms with my 67 230s (zeniths). It would buck at high speeds and sometimes blow a GIANT black cloud. The cause was a loose fuel line at one of the carbs. It was sucking in air at high RPMs. The black cloud is still somewhat of a mystery.

cheers

Anthony

[arkie]

May have found the smoking gun - I hope. I was putting the electric meter on all of the ignition components this evening, it was after dark, so I had a 12V magnetic base light plugged into the cigarette lighter. The ignition switch was in the run position, so I was playing with the points and heard a sizzling sound. I extinguished the light and found the sparking in the dark. The two primary leads on the coil were ARCING to each other AND to the coil lead (to distributor). Never seen this before, but it must be making the spark go crazy. I could wiggle the primary leads on the coil while running the timing light and make the timing go all over the place. I will change the coil tomorrow and see what happens.

[arkie]

Got a coil today and installed it - didn't help the situation much (stabilized idle just a little bit, but not much). I am beginning to suspect the condensor and points (haven't changed them out yet). I took the points out and cleaned them with my shirt - they were a little dark on the pads but not pitted. I gapped them to 0.016" with a feeler gauge - I don't have a meter to check dwell with. It started good but still has a bad miss and stumbles under load. Any guesses guys? Am I on the right track with the points and condensor? I'm getting quickly discouraged with this project - nothing I do seems to make much help. I changed a starter out on a 1980 Ford F-150 today, it took 20 minutes to do - I sure do miss easy fixes, readily available cheap parts, and easy access to components.

[psfred]

Check the points with a VOM -- should have less that 0.1 ohm resistance closed. I'll bet they are bad -- they are platinum plated, and if someone filed them or cleaned them with sandpaper, they are corroded and not closing reliably. They are also cheap, what $8?

If the transistor box is still hooked up, disconnect the condenser, it's only needed if you hook the points up "simple" (that is, directly to the coil), otherwise it can cause serious problems. Don't know why it's there, actually.

An ignition analyzer would be a great help at this point, since it can tell you the condition of wires, plugs, switchbox, and points.

Try new points with no condensor, you may be surprised!

Peter

[arkie]

I cut the wire to the condensor and voila - the car will fire right up and I could actually adjust the timing again. I've got the engine where it idles reasonably smooth, and it has good pick-up unless you give it throttle too fast (it will load up, engine speed will decrease and black smoke will cloud out the exhaust). I tried driving it, but it seems to have a steady miss or stumble under load. The miss doesn't seem to be there at idle without a load, but when I put it gear and drive it, it appears. I tried adjusting the mixture - I adjusted it lean to the point that it ran rough and backfired out the carburetor, then opened the mixture up from that. I am befuddled - when I get this POS running it will go up for sale and I will forget the idea of having a "weekend car" to "tinker with".

[arkie]

Here's a quick follow-up. I have noticed that the running of the car gets worse as it warms up - running rougher the warmer it gets. I was tracing all of the wires out to the ballast resistors when I found that the wire that goes from the points to the transistor switching box has been spliced, and also has a spot where the insulation is worn off and grounding out at times to the car body. I took the battery box out, and found that the battery acid has eaten a hole in the transistor box. I took it out and cleaned the inside (which was badly corroded) with contact cleaner. But at this point, I am going to ditch the whole point system and switching box and buy a Pertronix hall-effect set-up. I hope this fixes the beast.

[Oreo]

Arkie

Sounds like its very rich off idle.
Are you sure you don't have a vacuum leak?
And you're compensating with too much mixture at idle?
Is the carb piston spring in place?

BTW I prefer Crane systems myself. Easier fit for all makes. Be patient and hang in there

Oreo

[psfred]

Pertronix or Crane will fix most of your problems, since I think you have weak spark leading to fouled plugs.

If you have Bosch plugs and they have carbon fouled, they will have to be cleaned or replaced, they take nearly forever to recover from carbon fouling for some reason, unlike other brands. NGK don't suffer from this, clear nicely right away. So do Bosch Platinums.

By the way, if you have platinums, you need non-resistor plug wires, otherwise you get weak spark problems.

Peter

[Oreo]

Hi psfred

So in your opinion are NGKs superior to Bosch? Is there a NGK number equivalent to Bosch W7DC?

BTW - I have tried the Bosch 4 electrode coppers, thinking more is better. It is not. I think too much shrouding of the spark.

Oreo