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1971 eldorado 500 running rough, stalls at anything above idle

Started by sammidog, September 09, 2012, 09:12:40 PM

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sammidog

My 71 eldorado ran great for the last 5 years. It ran fine on the way home for 5 miles. When i went to put it away it stumbled and missed at idle to the point it barely runs. I rebuilt the carb, used fresh fuel and it still does it. Newer wires, fuel pump good, newer cap and rotor. I thought maybe it eas the coil.  I bought a new one and the motor will not start with it. I put the old one back on and it starts but runs poorly. The coil i bought said requires and external resistor. Does the original coil have an external resistor? Also what can be the problem here?

62droptop

if you are still using points,maybe points are the culprit, either the dwell adjustment or burnt tip,condenser in distributor will also cause issue

can be many issues at play here
vacuum leak,fuel issue,ignition issue, mechanical issue like stuck valve or head gasket issue,possibly timing chain jumped

may things can cause whay you are describing

some mor infor would be helpfull and i am sure someone will chime in

where are you located, possible someone close by that may be able to help



TJ Hopland

I am pretty sure 71 had a resistor wire feeding the coil if everything is original. 

I too noticed you did not mention anything about points or any sort of update or conversion.   A tach / dwell meter would quickly tell you if you are still dealing with a fuel issue or ignition.  This big of a problem should be fairly easy to track down. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

sammidog

To be honest i cant figure out if it still has points. I think so because it has a system that rubs against the cam in the distributer but i cant see tha actual contacts. The spring and weight system appears new. One other thing. I put a timing light on it and i can see its not getting spark on occasion. It totally variable as to when it quits.

The Tassie Devil(le)

The way to see the points is to remove the Distributor Cap, and then the Rotor and all will be revealed in 3D.

A simple observation of the condition of the points gap will show you if it is requiring adjustment, and as a starting point, if you don't have a Dwell; Meter handy, is to set the gap at .015".

Mentioning the intermittent spark, I would be looking at the coil itself.

One way of checking the coil, is to put the timing light on the actual cap to coil lead, and if that fluctuates, the Coil is the problem.

BUT, remember that the light will be flashing as though it is on steroids as it will be flashing at the rate of 500 times for each 1000 Revolutions per minute of the crankshaft.   And you will be surprised at the results, if the coil is at fault.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

TJ Hopland

If when changing the rotor you were looking directly at the weights and springs it sounds more like an HEI.  Its been a while since I worked on a gm points distributor but typically the weights and springs are fairly well covered by the advance and breaker plate.  The HEI was the later factory system that had the coil installed in the cap.  I would guess you would have found that out when you went to buy the parts since nothing is the same between the HEI and points systems.

Can you post pictures of the distributor?   Maybe its got a Petronix sort of thing in it?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

sammidog

Thanks bruce. Thats a good idea. What threw me is i tried a new coil and it wont start at all. The old one gets the motor to start but run poorly. I guess i coyld have got a bad one from the box. I bought a BWD fron advance auto. For a few bucks more i can get an accel.

sammidog

Interesting tj. Yes, when i remove the cap, there is a rotor which is round and takes up alot of space under the cap. I remove that with 2 screws and there are the weights and springs. Underneath that i see what looks like a points and condensor set but dont see the actual contacts. It does have a regular cylinder shaped coil outside to the driver side of the ac compressor which is dead center

TJ Hopland

I just refreshed my memory and forgot the GM V8 points distributor did have the weights up top right under the rotor.   If you are seeing the round thing that is the condenser which is part of the points system.  The conversion kits remove that.

I would say the next step is to get a new set of points.  A tach / dwell meter would also be a good thing to have.   For points try and get Standard brand Blue Streak model.   They are the only ones I have seen in the last 10 years that seem to be the quality of the originals.  The other 99% out there seem to be poorly made and won't last.   One of the reasons I suggest a dwell meter is to see if perhaps we are dealing with badly worn bushings in the distributor.  Its unlikely for that issue to come on suddenly but could be contributing to the issue.  With a dwell meter connected you just rev the engine and look at the dwell reading.  It should be smooth and fairly steady.  If its jumping around the bushings are worn.   

StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

sammidog

Everything looks like new under there. The weights and spring look like they were just unwrapped. This was my dads car and he never drove it much. Any work done on it was 8 years ago bur if the car has 800 miles since the work was done id be surprised.

Guidematic


Go back to the basics. Since no real work has been done on the car for 8 years, I would simp,y replace all the items that would have made for a major tune-up. That would include plugs, points, condensor, rotor and filters. Since you have already replaced/rebuilt or repaired other major components then this may just well do the trick.

The coil calls for an external resistor, which your car should have unless it's been modified in some way. This is a resistor wire built into the harness. The AC Delco number is E552C, Standard Motor Products is UC12T. These are good high quality coils available at many parts stores. Maybe the new one you have is defective.

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

TJ Hopland

This is what the point set looks like.



The end of the silver screw sort of points to the actual switch contact.   Sitting can be hard on them.  One of the old tricks was to bump the starter to position the contacts so they were closed then take a dollar bill and run it between the contacts.  The idea is the bill has just enough of a texture to it to take off any light corrosion without damaging the plating.  For more serious wear there was some mini files that were called a burnishing tool. 

I have also seen it many times on engines that sit where the pivot gets stiff and sometimes the contacts dont close. 

A dewll / tach attached will tell you if you are getting a good steady signal from the points.   If you are then you would be looking at the coil or further down the system.  If you are not getting a steady signal you are back to dealing with the points.   The plate the points mounts on is connected to the vacuum advance so it has to pivot as the advance signal changes.  This means that the black wire from the points to the coil has to flex.  Its possible that it is rubbing on something and has shorted to ground or that it has developed internal cracks.  There is also a ground wire inside the distributor that grounds that plate to the body of the distributor.  IF that wire broke you would likely have intermittent contact also.   Most of the time the vacuum advance is running off a ported vacuum source which means its off at idle. As soon as you come off idle you get vacuum and the advance moves so a broken wire would fit what is going on.  With a dwell or tach hooked up try revving it.  If the signal drops out unhook the vac advance line and try it again.  If its fine you now know where to look.   

 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

sammidog

Thanks guys. I do have a dwell meter so i can give that a try. As far as reving the motor it wont run past probably 1200 rpm at best. Maybe not even that much. When i first start it it runs pretty smooth. Then within 15 seconds it starts to shake and studder then all of a sudden will run smooth for 5 seconds then start all over again. Thought for sure it was water in the gas but used fresh and same thing. Definitely electrical given seeing the timing light fluctuate with the studder.

Gene Beaird

That sounds like timing is way off.  I'd definitely check the dwell.  If nothing has been done to the car in a while, the points could be corroded.  Had a set fail me on our 68 Calais that we inherited from my Grandparents.  It would occasionally just quit running while driving it around the storage lot where we kept it at the time.  It eventually just quit running.  I figured it was fuel, but I put a timing light on it and got nothing.  I eventually chased it down to the very corroded and pitted points.  New set, ran great.

It would run good until it quit running, and IIRC, it would shut down when I mashed the gas.  Sometimes I'd just let it cool a few minutes, and it would fire right back up.  That was until the total failure. 

Gene Beaird,
1968 Calais
1979 Seville
Pearland, Texas
CLC Member No. 29873

sammidog

Good news bad news! Good news is its fixed 90% bad news is i dont know what i did to fix it. First put new axcell coil. No help so i put the old one back on. Put dwell meter on and it read 27 and steady even running like crap. I removed the cap and can now see the points but cant get to them to clean the contacts without removing the whole set. I didnt want to do that for adding another variable into the equation. I sprayed contact cleaner inside and outside the cap and a little shot at the points contact. Let dry and replaced. Problem 90% solved. Of course now i dont know what caused it. Is 27 and steady the proper value. It does not change when i rev the motor.

sammidog

I dont want to call it fixed. I guess following guidmatic's advice is best. New points cap rotor condensor, wires.

bcroe

If the car has the original timing chain, I suggest you get it replaced.  Might
help now, will avoid disaster later.  You can check for chain slack by rocking
the crank and watching rotor motion.  Bruce Roe

The Tassie Devil(le)

I think the correct degrees for the Dwell is 30.

Plus, I second checking the "slackness" in the timing chain by turning the crank as Bruce recommended.

Any engine that has stood for a long time, with these Nylon Toothed cam gears are more likely to destroy themselves than a long-running engine.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

sammidog

Thanks guys for all your help. New cap, rotor, wires, coil,plugs dwell set at 30 and im back up and running. Maybe just all parts a little off causing a big problem. What would be a ballpark price to have the timing chain replaced at a shop. That job seems a little out of my league.

TJ Hopland

To properly do a timing chain in an Eldorado the engine and transmission have to be separated because the transmission blocks access to the oil pan. This means engine or transmission have to come out.  Reason is like most engines the oil pan seals to the timing cover so the oil pan is supposed to come off first.  Its also a nice thing to have the pan and oil pickup off to clean out all the bits of cam sprocket and valve guide seals.  There is a way to cheat and get the timing cover off without dropping the pan but usually you end up with a leak and there are a few things that can go wrong and cause you to have to drop the pan anyway.   

You can see the edge of the sprocket and chain by removing the distributor.  You can't see it all but as long as the engine is not real filthy internally you can usually tell if its plastic and get an idea how worn it is.   If you or your shop has a bore scope you can get a better look at it.  Might be worth doing as the next step so you can either plan for it or know its not your problem.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason