missing and bogs down after 15 minutes driving

[myred63]

More data points to consider and heat questions:
Replaced the regulator Saturday. Went on a drive and was great for 20 minutes. Strong, no pops or hesitation. Just as I would expect. Then after all was heated up after 20 minutes, I started to get the misses and bogs down a bit. Got back to the garage and left it running taking Voltage from the distributor side of the coil. Still at about 8v just the same as when I left. Timing is at 12-13 deg or so. It increased when revving up the engine. Dwell is at about 30 deg. Now touching the coil and the generator, you can not leave you finger on them, they are too hot. Is this normal? Flaps for cold mornings are pushed closed. Then the next day, went out for another drive for 20 minutes or so and it started acting up with pops during acceleration and bogs down. I opened the hood (over the engine) and continued to drive and in 10 minutes, it was running great. Strong and no bogging down with smooth acceleration. After another 20 minutes of good driving I closed the hood on the engine. 10 minutes later, the problems came back. This is in Santa Barbara, CA, at 65 deg at 9:00 am, so ambient temp is no problem.

This tells me I am overheating. I will have to get a temp gauge to figure this out. With an air cooled engine, cool air outside, I should not be over heating. The blower is running off the belt, the bellows are wide open at the rear and I can feel plenty of air exiting out of the bellows door. What could be over heating? No generator light on.

[bbodie52]

Just a thought... is it possible that your generator is overcharging? I know you replaced the voltage regulator, but if there is a wiring fault at the regulator — such as a poor ground — the output of the generator might not be regulated properly. A faulty generator, such as a grounded field, could cause the output to go unregulated. Generator voltage output increases with engine RPM, so an idling engine might read a normal voltage input at the coil, but an engine running at driving speeds with an unregulated generator (and a resulting high voltage) could explain the hot generator and hot ignition coil. The generator light would not come on under overcharging conditions, since it only comes on when there is no generator output. It does not indicate excessive output voltage problems. An overheated electrical system might begin to fail and break down electrically, so an overheating coil would begin to misfire with continued operation at an excessively high charging voltage. Under those circumstances the ignition points would be arcing, pitting and burning over time too. Have you measured the voltage across the battery terminals — both at idle and at high engine RPM? If it climbs above 14 volts or so and stays high the generator and ignition coil would overheat over time and then would begin to break down.


There are some charging system quick checks on page 8-3 of the attached shop manual section that may help.

[myred63]

Conducted another test. We thought that the coil getting really hot was a problem. With longer leads, we taped it to the bumper outside the car. Closed the hood and drove around for an hour with NO problems at all. Very strong and smooth. When arriving home, we touched the generator. Could not leave you finger on it. How hot is your generator after an hour drive? We also checked the generator charging current. After an hour drive, voltage to the battery was about 14V. At high revs, it was 14.3 also, voltage at the distributor side of the coil was about 8V then at higher revs, went up to 9-10. Seems to me my engine is getting too hot. The Gen light does not come on. If it is normal for the generator and coil to get too hot to touch, then I guess a new coil is needed if this one fails when hot. It was replaced in 2011. Still searching for the silver bullet. Is there a digital temp gauge I could get to monitor the head temperature?

[Danny Joe]

Harbor Freight has a handheld one for $36.

http://www.harborfreight.com/non-contac ... 61894.html

[Darrin]

Based on my experience...I say bad coil. Swap it out and drive on....hopefully.

Darrin

[flat6_musik]

I agree about the coil! I mean, if that "did the trick" to eliminate the problem......can't argue much with that.

I don't what to say about the generator. It's doing its job with those voltages you mentioned, but......geez, if you can't even touch it, that doesn't seem right either. Weird. I think it's got to be soaking up some of the engine heat, just by being mounted to it.

[myred63]

YES YES YES. It was the coil. Got a $24 coil at the local car store. Put the coil in and drove for 2 hours without a miss fire or bog down at all. Smooth acceleration with no problems, even at highway speeds. I'll test drive more next week and give a summary of this problem for future reference for anyone else having this behavior. Thanks for all the help. I'm sure I will need more at some point soon.
Jon

[myred63]

Just drove the Red63 from Santa Barbara to Newbury Park today. 45 miles. It ran great. No problem cruising along at 60 mph the whole way. There is a long grade just before Newbury Park and the car was strong and was able to continue up the long hill at 60 mph. Seems like the car is running as designed. One question for you all, take a temperature reading of the coil with a hand held infrared thermometer and let me know what temp the coil is at. Still can't touch it after a drive, it is too hot. I have one at work and will test it this week to see how hot things are getting.
Jon

[bbodie52]

I always thought that the coil would run much cooler if it wasn't bolted to a stud that projects from the right cylinder head. There must be some heat that is conductred from the head to the coil bracket and to the coil. If it was to be relocated to a mounting point on the engine compartment perimeter frame — away from the right cylinder head — the coil may run considerably cooler.

This simple relocation may reduce considerably the amount of heat and vibration the coil is subjected to, which could increase the operational life span of the ignition coil.

[flat6_musik]

I concur, wholeheartedly! Unbolt that thing from the engine and onto the body!!

[myred63]

That sounds like a good idea to get the coil off the engine. There is plenty of room to remount as your pictures suggest. That will be the next task. Also, the engine heating covers were removed for cold temperature driving. I pressed the sheet metal closed but they still do leak some hot air. I will get the set of plates that say "Remove for cold temperature driving" and leave them in. Being in California, getting all the heat out from the baffle vents is the way to go.

Vents1.jpg (69.42 KiB) Viewed 1016 times

Thanks,
Jon