OK, When you pull the headlight switch **** out, what effect does it have on the vacuum system. Is it supposed to allow the vacuum to pass through or block it? I have a vacuum leak somewhere in the headlight systemand I have not been able to isolate it yet. I have tested the vacuum tank, the relays and the headlight actuators. Everything is working properly. I used a vacuum pump on these parts. I pulled the headlight switch out and tested it from the override switch under the dash. It holds vacuum when on and allows flow through when shut off. The only part that I have not tested yet is the windshield wiper solonoid on the back of the tach. I tested the brake booster, distributorvacuum advance and the heater vacuum system and theychecked out . I am still baffled by this. The lines are all new. I can't find any breaks or holes and tested most of them with a pump and vacuum gauge. I know that I am missing something but I can't find it. The leak is big enough to effect the engine performance. I do get some backfiring with the vacuum, systems hooked up. Any thoughts????

 

Off is pass-through, On is blocked. Sounds like your switch is good. Sounds like your vacuum advance is advancing too far perhaps? Hook everything back up and check the timing. It might have been set with a bad vacuum in the system, making the base setting too far advanced. Now that you have good vacuum, it is advanced+advanced.

bill.

 

Also check and make sure the vacum advance is hooked up to the correct port on the carb.No vacum at idle and as you accelrate you get vacum to accuate the vacum pot on the dist.Is there vacum in the system when the car runs?Are all the vacum ports on the carb plugged?

 

Thanks for the info. Sorry I haven't responded sooner. I was out of town and out of touch for a week. I do intend to reset the timing this weekend. I will unhook the distributer vacuum advance to set the base timing. The vacuum advance is hooked up to the front metering block on the Holley carb. I have not tested the headlight system for vacuum yet because it has been too cold to open the garage door for any period of time. My garage is under the house (under the master bedroom). My wife supports and participates in my hobby but I still like to keep the peace whenever possible. I may have to wait a couple of weeks before I can run the car to take care of the timing and test the healight system. The wiper door system works just fine.

 

Ok. An update. Since the day was half way warm yesterday (55), I opened the garage door, started the car and did a little checking on the vacuum system. Well, I have about 19 inchs at the manifold. I checked the operating hose at the front of the car and there was only 5 inchs. That isn't enoughvacuum toraise the headlights. I have the vacuum system and the brake booster connected to the same source. I depressed the brake pedal and noticed that it was soft. So, am I asking too much from that source? I will try plumbing the brake booster to the carb base plate and see if I have enough vacuum for the headlights from the manifold without the brake booster.I am stillin a little quandry because the wiper door opens and closes just fine. All the hoses, filters, relaysand the vacuum solonoid are new. I will find this gremlin eventually.

 

Most power brakes I've seen have had a line direct to the intake manifold for vacuum source.

 

I have used a manifold vacuum port and the carb base plate vacuum port for the brake booster on different vehicles and did not have any problems either way. Since this was a new engine build, in foresight, I installed a two nozzle fitting in the manifold with the intention of running the vacuum system and the brake booster from the same port. At this point I am just guessing whether this is too much or not. I will have to wait another week or two to find out. It is in the teens out and a little too cold to open the garage door and let the heat out without a very good reason. I have a great wife that understands and participates in my hobby but she has her limits and I have the sense to know where those limits are. I still have other things to work on until it gets warmer.

 

I don't know if the '69 headlite vacuum is the same asthe '73 but mine has what for lack of a better name, I'll call a vacuum relay between the headlite actuators. I believe a low level vacuum signal actuates this "relay" which ports a large level (manifold vacuum I suspect) to the actuators. If yours has this system, you might check this "relay" for leaks. I'd check mine further but the engine is currently residing on a stand waiting for me to find the time to finish the suspension rebuild. [:@]

 

73Shark, How about some pictures of your ride? I have a '73 coupe too.

 

On a late 69 there is only one relay for the headlight actuators. I have tested it with a vacuum pump and it funtions correctly. I check the operating system hose at the relay and that is where I found only 5 in of vacuum. I tested the reserve tank with the pump and there was no leak down. I also tested the new booster and there was no leakdown there either. I will be waiting until it gets warm before I do anything else.