Can't find an answer by searching. How is the main harness connector held to the firewall? Mine is loose and flops around. Looks like maybe some screws. If so, what size? Also how does the connector come apart? Need help! Thanks,
Gary

Hey Gary, On my '67 the bulkhead connection is screwed to the firewall from inside the car. There are two 5/16" head screws that go through the fuse panel . On the engine side there are two harnesses that plug in with tabs on each end to keep them in place.

As Tucson '67 RS stated it is held with two screws that hold the fuse block and the female side of the bulkhead connector against the firewall. The screws could be missing or stripped out. If the fuse block is loose then it may be the screws. If it's the two male sockets on the engine side of the firewall the center retaining bolt may be missing or loose. I think that one is 3/8".
To remove the two harness plugs on the engine side of the firewall, loosen the center bolt about5-6 revolutions and then pull back on both plugs to get them started coming out. Continue loosening the center bolt some more while pulling out the connectors and when the bolt becomes fully unthreaded both connectors will come out. On my 73 and 74 cars the center bolt is retained with a clip so even if it does come loose it won't fall out.
One word of caution when plugging the connectors back in. Make sure all of the male and female terminals are lined up so they go into each other correctly. Years ago a neigbor was in a hurry and pushed the purple starter solenoid wire out of the engine harness connector by not having it line up properly before bolting it together and wondered why his car wouldn't crank. Luckily is was fixable and didn't require any parts to fix.

If the screws are stripped out you may be able to put some clips on them too hold them tight or make a small steel plate with a hole drilled into it to thread the screw into on the engine side of the firewall. I don't think you can put in larger diameter bolts unless you drill out the holes on the plastic fuse block and bulhead mounting ears.

Jim

One quick fix to the stripped out screw holes is to remove the fuse panel after you remove the connectors from the bulkhead. You need an assistant to help you with the next step. Have someone hold a dolly while you tap the sheetmetal flat again. The screws will now have grip through the firewall.