Join Date: Mar 2002
Location: Austin, TX, USA
This is long winded, but hopefully will help. This is the alternative to swapping parts.
Chewy, those old headlamps were quite as good by todays standards. But never the less, dim lights are probably caused by a bad connection in the electrical system. To find it you'll need to get a Digital Volt Meter and start measuring voltage drops throughout the circuit. Here is an example of what I'd check -- lights on.
1) Battery voltage at the posts.
2) Battery voltage at the clamps.
3) Voltage accross headlamp terminals.
4) Voltage between battery - and headlamp switch -- both incomming power side, and outgoing switched side.
These four tests should focus you in the right area of the circuit. For example if you measure 12 volts on one side of a connection and 10.5 on the other side, then you've found the bad connection. I generally like to see less that 1 volt drop accross any connection, but that is a rule of thumb. Head lights draw a fairly high current, so the voltage drops are likely to be a bit larger than an interior light circuit would for example. Your results may cause you to have to inspect other circuits more closely. If they don't pinpoint the problem, then use the same technique to hunt down the drop. Here are some examples of other area areas to check.
1) Fuse terminals.
2) Head lamp socket terminals.
3) Firewall harness connector terminals.
4) Ground from battery - to fender.
A battery charger would be a good helper. Also, keep in mind what your readings mean. You can measure directly accross a connection and expect to see less that 1 volt. You can also reference to ground (at the battery post) and look for more than 1 volt below your battery voltage. Presuming a 12.0 volt source. You should be suspicious of any connection showing less than 11.5 volts or so.
Once you find the offending connection, try to clean it up first. Use a little bit of sand paper to scuff off the oxidation. If this doesn't restore the connection, you'll have to replace the connection whether it be a connector terminal, lamp terminal, wire, etc. Also, once you find the problem and fix it, dope the new connection with dialectric grease. You can get a fat tube of it for about $3.00. For some reason they didn't use grease in their connectors back in 68.
[ 07-23-2003, 04:30 PM: Message edited by: dnult ]
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI