Sounds like you may have multiple issues that need addressing. First
the dead battery issue. My advice is this, first with all accessories
off and all doors shut and any accessory that could draw a load, phone
adapters ,cigarette lighter plugs etc removed, pull the negative cable
off and insert a test light or a cheap radio shack meter that measures
amps -in line- with the cable. An amp meter will give a better
indication of what is going on but if the test lamp is used and the
light is lit bright you have a draw on the system which over time will
kill the battery, to isolate the draw, start with the alternator plug
and main cable to the alternator and disconnect one at a time while
the test light/ amp meter is installed..when the lamp goes out you
have isolated the problem, of course this only finds it sometimes if
it is alternator related from a bad diode. (2) if this fails to
locate the draw then the next method involes a bit more time. Slowly
pull one fuse at a time to isolate which CIRCUIT is the draw occuring
on such as B/U Turn circuit which could be either or. This will help
determine and narrow the trouble making circuit. (3) earlier cars had
issues with clocks especially analogs that quit working mechanically
but that would still draw amperage trying to run, in that case it is
either disconnect the clock or replace it. (4) if the draw still
exists look to the battery and see if there are any other things that
are wired to the positive post such as MSD, AMps for stereos etc. then
remove those leads one at a time remebering to hook the positve cable
up tight and recheck for the draw. Stereo hacks are good for hooking
up all kinds of crap to the battery and some not properly causing amps
to stay powered up all the time etc. Also while we're on that subject
alarms and car starters are sometimes ghost issues as well. ( Having
fun yet)

Having the battery tested is also a good idea seeing that killing a
battery stone cold dead on a few occasions pretty much destroys them,
and if you can add water to it..well in my experience, especially on a
Vette where the battery is in a less than desireable area to service
is a waste of time and money. Buy a Delco completely maintenance free
and be done with it. I don't know about you but changing batteries on
Vette's needs to be a once every 3-4 year project not every year, plus
trying to stop acid leaks and corrosion due to water puking sucks too.

Battery cable ends also should be a crimped or soldered thing not a
1.50 temporary bolt together p-o-s.

The simple things seem to be more overlooked which fix more problems
than I can tell you.

As far as the MSD unit goes and the quitting, the MSD is awesome,
couldn't ask for better ignition however, BE Careful! This thing will
bite you bad. IF you have a bad wire etc. you'll find it the hard
way...OUCH.

The MSD unit should have it's own power and ground and the case of the
MSD does NOT have to be grounded to work properly. Most race
application MSD's have a rubber mount to isolate the unit from severe
vibration and hence it's own ground. Since wiring one of these can
take some time to be done right, I would suggest downloading the
instructions from MSD/Autotronics and verify proper connections
especially the Main power and grds which in my opnion should go
directly to the battery due to loads placed on these by the unit. If
you find these wired to a fuse panel or such remove and follow the
installation instructions to correct.

My suggestion on that is to get a digital voltmeter and connect the
voltmeter to the engine block then back to the battery negative
terminal when you are performing this stalling issue. Anything more
than .2-.5 volts indicates a bad ground and will cause issues. Seeing
the old vette is glass grounds become super important to prevent
feedback and weird related issues. I would also find where the
interior grounds back to the battery go and are connected properly to
the engine etc. The chev's used to use a strap from the operators
compartment to the rear of the cyl heads to properly ground the body
to the block back to the battery and like wise sometimes used a ground
from the frame to the engine or battery due to the rubber body mounts.

Check them all.

Sounds like a poor ground to me, you could setup a temporary ground
using a jumper cable to verify your concern also cutting the
diagnostic time down even more.

As the other gentleman said it may be a poor ignition switch, but the
battery may not be able to keep up with the load that is being placed
on it by the igniton and other things.

Charging voltage should be 13.5-14.7 volts and nominal voltage should
be 12.6 volts if not the battery is either no good, bad call or not
charged fully.

Like I said previously if it has been killed dead multiple times
replace it with a Delco and start the search from there. Never ASSuMe
anything when diagnosing. Follow these steps and it should provide
you with a genuine cause, that you can fix to resolve the issue
instead of throwing parts at it.

If this is going to be a car you drive a lot spend the time and do it
right.

Ps: A bargain Corvette is better than any Ford any day!

Thanks,

James D

Master ASE tech


On 14 Aug 2006 12:41:56 -0700, "Joe" > wrote:

>Hey guys,
> I just recently bought a 1968 Corvette with the 427,4spd,MSD
>ignition. Once I charge the battery the car will start fine and it
>will idle but once you put a load on it (tap the brakes, turn on the
>turn signal the car will die. No matter what I am revving the car at.
>I am new to the Corvettes. I'm normally a Ford man but I got a hell of
>a steal on this car. The previous owner replaced the battery,ground
>wire for the battery,voltage regulator and the alternator. Any help is
>greatly appreciated.