Mechanical Help Please (fouled plugs/erratic idle/hard start)

[72HCODE]

If it was the distributor/points/condenser would the symptoms change with RPM or be consistent across the board?

it would be all over the place. NOS unless its in the original sealed box from 1971 from ford and never used might be trustworthy. NOS does not mean the part is any good.

 

[Paul4425]

Well, turns out the old distributor does not work. No spark at the plugs, tested with a timing light (that was a waste of about two hours changing it and then changing it back). The new old parts do not fit the new stock style distributor. They have different internals. I'm out of time and patients for today. Will try again tomorrow evening.

 

[Carolina_Mountain_Mustangs]

I grew up with nothing but points and condenser. Usually when they get weak they will burn the points. I have had the condenser just die at a red light because the condenser went bad in 289 but always kept new ones in the glove box. The condenser does not have to be for that car as long as you can get it inside the distributor. My 1972 Suzuki motor cycle had one of the three condensers go bad while on a road trip. You can tell which one was bad with the cover off the spark across the points was much brighter flash not blue like a good one. I just got a condenser at parts house and hung in the dist. and got home and got the correct one at motor cycle shop. Yes they have different ratings but about any will work. If I remember correct the one for 351 C with dual points is the same as the 49-53 flathead mount and rating same.

We use to charge them up by letting a spark plug wire arc to the condenser wire and leave them laying around you would know when someone picked it up you would hear then holler, lol.

Crank the car over with cap off and it there is big flash at points condenser is probably bad or weak. If little spark usually ok.

I was luck to find several of the Autolite tune up in a can at a swap meet for $2.00 each. Points, condenser and plugs for $2.00.

I am still thinking something in carb causing the issue. Wish you had another carb to switch out.

 

[Paul4425]

I grew up with nothing but points and condenser. Usually when they get weak they will burn the points. I have had the condenser just die at a red light because the condenser went bad in 289 but always kept new ones in the glove box. The condenser does not have to be for that car as long as you can get it inside the distributor. My 1972 Suzuki motor cycle had one of the three condensers go bad while on a road trip. You can tell which one was bad with the cover off the spark across the points was much brighter flash not blue like a good one. I just got a condenser at parts house and hung in the dist. and got home and got the correct one at motor cycle shop. Yes they have different ratings but about any will work. If I remember correct the one for 351 C with dual points is the same as the 49-53 flathead mount and rating same.

We use to charge them up by letting a spark plug wire arc to the condenser wire and leave them laying around you would know when someone picked it up you would hear then holler, lol.

Crank the car over with cap off and it there is big flash at points condenser is probably bad or weak. If little spark usually ok.

I was luck to find several of the Autolite tune up in a can at a swap meet for $2.00 each. Points, condenser and plugs for $2.00.

I am still thinking something in carb causing the issue. Wish you had another carb to switch out.

Lol, I like the condenser prank. Might have to give that a try. I am also thinking it is more likely in the calibration rather than the ignition. Going to look harder into that today. I have the original carb, but it hasn't run in 25 years so it would take some work getting it operational.

 

[piper62j]

Question. Why did you swap out the original carb? Did you have this problem before installing the new carb? This issue seems to be fuel starvation and as mentioned before, just because the carb is new doesn't mean it's been assembled correctly. There may be a void in the casting or a crack somewhere inside making it run lean.. Adjusting the idle set screws should always make a difference in the running of the engine. If you turn the screws in all the way, the engine should stall out. If it doesn't, there is a problem with the carb.

Have you checked the EGR vale if installed? The diaphram should hold vacuum.. Also inspect the EGR plate for carbon build up which would plug the holes going to the valve.

Keep performing the process of elimination so it will bring you to the problem..

 

[Paul4425]

Question. Why did you swap out the original carb? Did you have this problem before installing the new carb? This issue seems to be fuel starvation and as mentioned before, just because the carb is new doesn't mean it's been assembled correctly. There may be a void in the casting or a crack somewhere inside making it run lean.. Adjusting the idle set screws should always make a difference in the running of the engine. If you turn the screws in all the way, the engine should stall out. If it doesn't, there is a problem with the carb.

Have you checked the EGR vale if installed? The diaphram should hold vacuum.. Also inspect the EGR plate for carbon build up which would plug the holes going to the valve.

Keep performing the process of elimination so it will bring you to the problem..

I swapped the original carb and intake during the rebuild. The car was not running when I bought it. The idle set screws do/did make a difference when I was able to get it to idle. It seems to be an excess fuel, not starvation (had loads of carbon on the plugs). No EGR installed.

 

[c9zx]

From what you said in your first post the engine has not run properly since being rebuilt. The calibration of the carb may be off for your application. Just as a hail Mary, I'd try removing the mixture screws and squirting some carb cleaner in the screw hole using the supplied small "straw". Reinstall the screws at about 1&1/2 turns out. I seriously doubt it will fix the problem but, it is quick and easy to try.

Calibration kits are available from Edelbrock based on the specific carb you have (I believe there are 4 650 cfm edelbrock carbs, 2 with electric chokes).

Here is a link http://www.edelbrock.com/automotive/mc/carburetors/access-calibration.shtml

Please let us know what you find out. Chuck

 

[wwhite72]

kinda sounded like a blown power valve...

 

[Paul4425]

Well, after a long week or so of troubleshooting I have the fix/fixes...The distributor points were not gaped correctly (way too close), and this was causing an erratic spark. I also discovered a spark plug wire that was not working consistently. The erratic spark and the wire were the reasons for the missing/thus the plugs were fouling due to the extra fuel in the chamber when it did spark. I am thinking the points may have moved when I was out driving it that day. I adjusted the points and also swapped the condenser for good measure. This fixed my idle issue. (Still a little unsure why this was only an issue at lower RPMs and why when the engine heated up it smoothed out for a while)

The second issue was that once under a load and driving the engine would surge. I am fairly certain this was due to the timing being too advanced, and the distributor vac advance advancing too quickly. Tomorrow I will start doing some road testing on this issue and see if I can get it set correctly. Right now, when the vac advance is hooked up it is backfiring out of the exhaust on the driver side. I still have some fine tuning to due (probably adjust the idle set screw on the driver side). But, the car is starting and runs very well without the vac advance hooked up, so I am definitely ahead from the last week!

-Paul

 

[Chris Womack]

Glad to hear that you have resolved the issue, before I switched to Ford Duraspark II distributor I had a breaker point distributor and still recall some of the experiences with points and condenser failing.

 

[Paul4425]

Upon further testing and investigation, points suck. I was still having issues when it was under a load. I broke down and swapped the points and condenser with a PerTronix electronic ignition. It fired up perfectly and ran like a champ. No hesitation or bogging under a load. That will be the last set of points I ever deal with. It was definitely worth the $85 dollars.