[Alf ista]

Hi all. I have a problem with my GP that I hope you can help me with. Car is a 64 GP with a 400 and 400 transmission. HEI distributor with an MSD box and separate coil. A while ago the car broke down and the problem was found to be a burnt out distributor cap. Not sure why that happened though. Cap was replaced and car was mostly fine after that. Yesterday evening though I was out for a spin and it cut out on me again. I pulled in and checked all the visible wires. Gave them a wiggle thinking it might be a loose connection and then it started up fine. Appears to have fuel and spark ok. Tried to cut out a few times on way home but mostly started up again before I came to a stop. Narrow country road on way back so that was a bit traumatic!! Managed to get home and checked things over. Thought the ground connection to the battery may have been a bit loose so tightened that. Nothing else really obvious. I did look in the voltage regulator on the inner fender though. There are two solder connections that appear to be connected by a thin wire. However the wire is broken in between. I am not sure if this is the way it is supposed to be. I have looked online but cant find anything to confirm. See photos below which show the regulator. You can see the two solder connectors on the top left hand corner below the yellow spade connector. Should they be connected? I would appreciate any advice to confirm if this connection is correct or any other help on what my problem could be. Thanks in advance. Hugh.

[25stevem]

Can you post up a picture of your alternator please?

One suggestion I can offer to start to hone in on the issue is to ditch the MSD and also go back to having the coil in the HEI cap.
You do not need the MSD with a HEI anyway !

[25stevem]

I quick off then on aging cut out when driving can only be electric related as in a 12 volt cut out to what’s powering the ignition system, or a electronic cut out from the ignition system itself.

A fast off then on type issue can not be fuel related if you do not have fuel injection.

[phil400]

Not sure about msd stuff but I've had frayed pickup coil wires cause the exact same issue.

[25stevem]

I only see one wire going to that reg, so he must have a internally regulated Alt.

[Alf ista]

Hi guys. Thanks for the feedback. Some pics attached. Excuse the messy wires! Car was restored in the States before being exported to Europe some years ago. I have it about 10 years and has been pretty trouble free motoring since. I have been upgrading it bit by bit. Recent change was a new steering box. Under the hood though remains much the same as it left the US. I did remove an old ballast resistor not long after I got it after getting advice on here at the time. The alternator has two wires going to the one post on the rear of it. There is an inline 30amp fuse on one of the wires going to it. I just had a look at it and it was badly burnt out but not blown. I replaced the fuse for now and will get a new fuse holder in a day or so. Car is running fine in the garage. Have to say I am nervous about bringing back out on the road now without knowing what is causing this...

[25stevem]

That’s a internally regulated Alternator so what you think is a regulator on the wheel well is nothing more then a terminal block for some wires.

Your cut out issue is that 30 amp fuse wiring. You need a much bigger fuse with the heavier wire that goes with it.

The fuse and wire must be rated for how many amps that alternator is rated at which should be stamped on its case somewhere..
I don’t think a internally regulated alt was even made that put out less then 40 amps, but you could go online and look if you can’t find the stamping on yours.
Poor connections will burn up in time even if the wire gauge used is up to the needed spec!

[Alf ista]

Thanks for that. I am trying to replicate what happened out driving. So I started the engine and wiggled the fuse. Nothing happened so then I just pulled it out. The engine kept running though. Would you expect that to happen? I guess its not the same as driving down the road. Will see if I can find a model number stamping on it so I can check the amperage.

[25stevem]

Yes, if the battery is good you can do as you did with the fuse and it will stay running.

[Goatracer1]

From what I can see you have NO wires to energize or regulate the alternator so you have a "1 WIRE" self energizing alternator. That ONE wire is OUTPUT only. In your case someone added a second output wire. The second wire could power your AC high blower speed. I do see that your compressor is missing. I do agree that there is no reason to have both the MSD system and the HEI. From what you have said you are using the HEI distributor for the magnetic pickup only. It is that magnetic pickup that could be causing a problem. Remove the dist. cap and check the two little wires that enter the pickup and check for cracks. Give them a tug and see if one or more break off. It is very common for them to break off the pickup because they move back and forth as the distributor advances.

[Alf ista]

Hi all. Seem to have this sorted. I think it may have been something as simple as a poor ground connection. I have one of those disconnect devices on the battery. The MSD ground is connected direct to the battery. The disconnect device was a small bit loose so was dropping ground intermittently. This might not make much difference normally I suppose but it meant the MSD box stopped working and thereby probably stopped spark to the distributor. At any rate I replaced the burnt fuse holder from the alternator (still not sure what its for) ,ditched the battery disconnect and went through all obvious connections. Runs like a champ now again. I was about to get rid of the MSD box and get an in cap coil etc but seems ok now. Will still keep that in mind for future upgrades though. Thanks for all the help and advice. It is much appreciated. It has also improved my electrical knowledge a bit so all good. Hugh.

[25stevem]

For aftermarket electronics stuff like the MSD that you have a good ground connection is essential, in will not only fail to work right with a bad ground connection, but it can just outright fail completely on you .