I did a cursory search in the forum for similar posts, but do to time constraints I did not read all of the dozens of pages of posts that came back.

My carb worries seem to be behind me. She appears to be running strong and is driveable again (hurray!). In any event, I ordered a rebuilt Autolite 1101A for a 65/66 I-6 from RockAuto yesterday, just to be sure.

The manual says that to fine tune the mixture and idle speed the alternator must be active and so to turn on the headlights. When I do the engine cuts out. I just tried this and before she spun all the way down I turned the switch back off and she sprang right back to life.

Question: Is this a classic symptom of some documented defect in a component like the regulator or alternator or is the wiring/switch the most likely suspect?

Thanks.

 

Sounds like a low idle speed. Did you have the engine fully warmed? Did the engine cut out, or die down?

 

Does it chug and sputter until it finally dies? - That's low idle speed, improper mixture, vacuum leak or any combination of these.

Does it just cut out? - That's an electrical problem, disconnected wire, miswire or short.

 

At idle it sounds like its running pretty smoothly, but I did just reinstall the carb after a rebuild, so it could be mixture/idle speed related.

Was it fully warm? The manual says to let it run 30 minutes before fine tuning the idle speed (and turn on the headlights). No it wasn't run for 30 minutes, but for 10 and a taken for trip a round the block. No indication that it wanted to stall.

It doesn't mess around when the lights are turned on. It cuts out really fast. No chuggin', belching, gasping, just done.

Thanks for the opinions.

 

if it dies when you pull electric power. I would trouble shoot electric.

Clean the grounds, check the alternator output. If that is OK then take a pair of jumper cables.(fprget red and black for now) connect one lead from either cable to the neg on the battery, then connect the other end of one to the engine,and the one left to the bumper... try it then. My first impression is you have no ground strap some ware.

you should have straps going... 1from batt to body- 1 from body to frame-1 from frame to engine. and dont forget the neg pn the batt on the block.

 

If it does it only when you put a load(electrical) on it...I would look at the alternator or regulator...regulator is cheaper of the 2...bad grounds is another...originally there was only 2 major grounds...battery to block and block to cab. theres other grounds on the alternator wiring harness...those 2 on either side of the core support by the voltage regulator on the left and the other one between the battery and support on the right...undo the bolts, clean the wires and reconnect...clean the sheet metal too of course...Also, have a look at the alternator wiring itself...if the wires look wicked nasty...lots of exposed or previously spliced wires. those also would be suspect as well...clean battery cables in good shape help alot as well...


IMO, it doesnt sound like a carb issue at all...also...when you turn on the lights...what does the alt gauge do?? Or if it only has a light, does it come on and stay on until you increase engine speed...if so, idle could be low as well as the electrical stuff mentioned above...If you need a regulator, let me know as Ive got lots of them.


- cs65

 

It should still run, even without the alternator. I did it for several months only on battery power until I could afford a rebuilt generator. That included driving at night with the lights on. I think it's an electrical connection or maybe the result of a bad harness.
I notice that the rpm drops on mine slightly when I turn on the headlights. My harness has seen much better days, too.

 

Thanks for the advise. I guess I'll take a look at the grounds first. I've got a second voltage regulator already from earlier electrical diagnostics.

When I rebuilt the carb I took the manifolds off and swapped in a newer OEM exhaust manifold. It had a D0 (1970) part code to replace the C5 coded original that was cracked to pieces, litterally. The later model is a heavier casting and to get it on I had to remove the alternator bracket. The bracket and alternator went back in fine once the manifold was in place, but the bracket was too confining to slip the manifold in behind without removing it.

I photographed the wiring on the back of the alternator before removing it and was certain I got everything back in the right spot, but I'll be double checking that too. The wires and boots were in surprisingly good shape.

As far as the ALT light (no guage in this slick) I just went and tried two things. First I turned the lights on without starting the motor to be sure they worked at all. They did. Started it up, let it idle for about 1 minute. Pulled the switch, lights went on, engine kept running, could barely tell a difference in the idle speed/engine rumble. So it's fixed with me doing nothing...I doubt it. If there's one thing I can't stand (and let's face it, there's plenty of things I can't stand, but this one's high on my list): intermittent problems.

Nonetheless...I'm going for I ride.

Thanks.

 

Electrical "Gremlins" are funny creature technician's, that like to play tricks on the unsuspecting owner.
Do not assume it's fixed.
Take the advise previously posted. Check and clean all ground areas. Make sure all ground straps are there and in good condition. If it went out once it will do it again. Drive during day with lights on to monitor it. You don't want to try it while far away from home at night.

 

Here's a quick way to check the voltage regulator: With the truck running pull the battery ground cable off, if it the truck dies the voltage regulator is bad, if it keeps running when the battery ground cable is off of the battery then voltage regulator is OK.


Hope this helps!