So I have a 67 that I recently (well over the last 2 years, don't ask) converted from manual drums to power assisted discs in the front, all new SS brake lines (never get SS if you want my opinion) and all new everything literally, except for the brake pedal and drum backing plates.
So as I guessed might happen, I don't have enough vacuum for the power brakes. I was thinking canister, but at this point I might as well just buy a vacuum pump and finally put this baby to bed. Soooooo, I was looking for a place to hook into an ignition switched 12 v source. As I'm staring at this rusty old fuse box I see the Ign Switched terminal has a line to it. I trace it back to the engine bay and it is just grounded to something.
Is there any reason for an ign switched line to be grounded? Was this something related to a points ignition that got replaced when I switched to a Mallory electronic ignition?
I checked to see if it had any voltage to it, but it didn't and I had to leave for the evening. I'm guessing if it did have voltage at one time it would have immediately shorted and blown the fuse. The car starts and runs fine, this just seemed odd.
Tonight I'll check the fuse, clean the rusty terminals and then see if I get any voltage. I also had turned the car to on, but didn't actually start it.
I would like to hook the vacuum pump up on a circuit with 15 amp fuse, so I would like to avoid the other numerous piggy backs that run the radio and accessory gauge lights and just have it on its own circuit. I'm obviously not very electrically savvy, but assume piggy backs aren't the best option. But then again I'm not opposed to it, since I don't think the stereo and few bulbs for the gauges and tach draw that much current.
An option might be manual discs. My friend has a 69 with manual discs and they work fine. Just takes a little more muscle. I second the . stainless comment. I did a stainless fuel line and I was sorry. Nothing wrong with the stock type plated steel lines for cars that seldom see wet or salt.
So I have a 67 that I recently (well over the last 2 years, don't ask) converted from manual drums to power assisted discs in the front, all new SS brake lines (never get SS if you want my opinion) and all new everything literally, except for the brake pedal and drum backing plates.
So as I guessed might happen, I don't have enough vacuum for the power brakes. I was thinking canister, but at this point I might as well just buy a vacuum pump and finally put this baby to bed. Soooooo, I was looking for a place to hook into an ignition switched 12 v source. As I'm staring at this rusty old fuse box I see the Ign Switched terminal has a line to it. I trace it back to the engine bay and it is just grounded to something.
Is there any reason for an ign switched line to be grounded? Was this something related to a points ignition that got replaced when I switched to a Mallory electronic ignition?
I checked to see if it had any voltage to it, but it didn't and I had to leave for the evening. I'm guessing if it did have voltage at one time it would have immediately shorted and blown the fuse. The car starts and runs fine, this just seemed odd.
Tonight I'll check the fuse, clean the rusty terminals and then see if I get any voltage. I also had turned the car to on, but didn't actually start it.
I would like to hook the vacuum pump up on a circuit with 15 amp fuse, so I would like to avoid the other numerous piggy backs that run the radio and accessory gauge lights and just have it on its own circuit. I'm obviously not very electrically savvy, but assume piggy backs aren't the best option. But then again I'm not opposed to it, since I don't think the stereo and few bulbs for the gauges and tach draw that much current.
You should have lots of vacuum available. A pipe comes off the back of the carb directly into power brake booster. I assume you have a brake booster.
X2 On You & Bob's comment on SS lines.
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I have vacuum available, but I have a pretty wild camshaft so I only have about 14" of vacuum. I believe 18-22" is ideal. Currently it's ported to the intake manifold.I would have kept it manual brakes, but Id rather buy a vacuum pump ad canister than buy a manual master cylinder and have to redo brake lines to get them to match. I was just curious if anyoe knew the function of that port on the fuse block, but now i see photobucket doesn't allow picture sharing. I'll see if i can find a better picture hosting site.
So weird thing, I disconnected the wire and the car wont start. Just cranks over. Plug the wire back in and boom, fires right up. It's llike its a ground for the ignition or something. I'm guessing its something to do with switching from points to HEI. Better find another port for the vacuum pump.
HEI needs full 12V so it sounds like that was used to power the ignition. The original power for the ignition is through a resistance wire that drops down the voltage to the points
Can't think of a switched source that goes directly to ground, wouldn't last long unless there was some type of device between the source and the ground. Is it grounded directly to the body or block? I know people who run vacuum assist with less than 14" of vacuum. Did you actually try yours and there was not enough power assist? Do you have one of those small diameter boosters?
So it's is grounded directly to the frame. I don't have a good wiring diagram for the fuse block on the 1967 firebird otherwise I could just see what is one the firewall side of the fuse block and see if I could figure it out. I have the diagram from the '67 Pontiac manual, but it is different than the firebird and the firebird supplemental manual only has a picture of the fuse block but no details on the wiring.
Next to ign fused it has the fuse for bk up and gauges directly to the left of the terminal.
I'm not sure if the image from my first post shows up so I'll try again here and see if this works better. Photobucket apparently quit hosting images so every forum is just filled with blank images, but I digress. Giving Imgur a try.
As for the brakes. I only have about 10-12" vacuum as of last night. The car does need a tune bad, but since the cam is basically a regrind of the ponitac 041 in a 400 ci I don't think I'll get much more vacuum.
The brake kit has a 9" booster. Its the right stuff detailing AFXDC14. I did a small test drive around the neighborhood a few times. The power brakes work at first, but then it feels like once I press them halfway, they turn back to manual brakes.
I ordered a vacuum/boost gauge, a vacuum canister, and a vacuum pump. I'll install the canister first and see if that helps, then if necessary I can add the pump as well. I also will test the check valve on the master cylinder, but I think it is fine.
So I think it has something to do with the Mallory unilite ignition I added years ago. I think it may be bypassing the resistance wire so the distributor gets a full 12 volts. Not sure why it is connected to the ground though and not to the + side of the coil. I'm also running a ballast resistor instead of the resistance wire. Wish I could time travel back to 1994 when my uncle helped me install this and see if he could explain it to me. I guess it doesn't really matter since the car runs, but I would like to understand exactly what the deal is.
Ahhh wiring mystery solved. Turns out I'm just an idiot. Two identical wires go through the firewall. One goes to the ignition and one was hidden and is a ground. Somehow missed that. Anyways, does anyone know if its sae to piggy back off an acc fused terminal in the fuse box or if you can tap into the horn relay? Don't want to over draw.