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Discussion Starter #1
Hello all,

I've read a lot of material on this forum, but this will be my first post. I've had a 1968 coupe with the 200 I6 and C4 automatic for about 8 years now. 2 years ago I upgraded to power front disc brakes. I've never been able to figure out the "correct" vacuum line routing for these! My current routing is:

Intake manifold -> brass angled fitting -> steel line up over the valve cover -> brass tee -> right to brake booster, bottom to steel line to C4 vac. modulator

This seems to work fine (with the exception of the plastic tee I was using, which broke, leaving me stuck in 1st gear... replaced yesterday with brass tee). That being said, what is the "correct" vacuum routing for this setup? Here's a few questions I have for clarification:

1. Were 68 200's optioned with power brakes? (Also what about 67? I know IMCO on 68's make for much more complex vacuum routing, though I think that's independent of brake/trans vacuum routing.)

1a. If yes, how were the vacuum lines originally routed for a 68 200 with power brakes and a C4?

2. The current steel line from manifold up over the valve cover is sometimes marketed as the transmission vacuum line, sometimes as the booster vacuum line. Which is it really? Did Ford use it interchangeably depending on options, or is it a more modern thing to use it for either/both?

Thanks for taking the time to answer this! I'm not going for concourse, as this is a daily driver, but I like to shoot for original or at least be knowledgeable about what's original so that I can modify accordingly.
 

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IIRC, the routing is indeed street elbow to steel tube, up to top of valve cover 90° bend to rear of valve cover (with a piece of rubber hose on the pipe to prevent rattles), then rubber hose to booster valve. Auto trans, if equipped, is fed by the other nipple on the booster valve. The tube could be either function, although I think the auto trans dedicated item necks down, while the PB does not.
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Discussion Starter #4
IIRC, the routing is indeed street elbow to steel tube, up to top of valve cover 90° bend to rear of valve cover (with a piece of rubber hose on the pipe to prevent rattles), then rubber hose to booster valve. Auto trans, if equipped, is fed by the other nipple on the booster valve. The tube could be either function, although I think the auto trans dedicated item necks down, while the PB does not.
Alright, good info. My steel tube necks up, pointing vaguely towards the booster, but much like in the pic you posted prior to installing power brakes, a rubber hose makes a 90° bend to the steel line sticking out near spark plug 6. If I'm understanding you, are you saying the check valve on the booster should have 2 ports, and the 2nd goes to rubber line to the steel trans line?

Now this is really interesting...
Mine was originally an IMCO with most of the equipment missing and the manifold ports clumsily blocked off when I got it. I swapped to a non-IMCO head and no longer have any of the IMCO equipment, so on the head side I'm probably more configured like a 67. I had the same vacuum block on the manifold.

My distributor vacuum advance is hooked up the same, albeit with a 1/4" rubber hose.
PCV is same.
Not sure what DCVC stands for, but I'm gonna guess it's the vacuum retard for the distributor? I've capped that at the distributor (inner port) and no longer use it.
Is that trans line really correct? It looks out of place to me, but I'm no expert by any means.
For the brake booster, I see that port is blocked and the photo is not of a power brake car. Would that have been a 3/8 rubber hose to the booster or some sort of steel line?

My vacuum block was rotated the other way (180°) with the threaded port facing forward, so the steel line comes to the front a little before going over the valve cover, much like in the pic 22GT posted. Now it's just an elbow because I'm not using any more than the threaded port. I've seen this pic before and it baffles me, but only because I'm trying to learn and understand this.
 

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Discussion Starter #5
Also, not sure I wanna open the can of worms with the whole IMCO routings, so would it be more appropriate to be asking about 67 configurations?
 

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Alright, good info. My steel tube necks up, pointing vaguely towards the booster, but much like in the pic you posted prior to installing power brakes, a rubber hose makes a 90° bend to the steel line sticking out near spark plug 6. If I'm understanding you, are you saying the check valve on the booster should have 2 ports, and the 2nd goes to rubber line to the steel trans line?
Yes.
Now this is really interesting...
Mine was originally an IMCO with most of the equipment missing and the manifold ports clumsily blocked off when I got it. I swapped to a non-IMCO head and no longer have any of the IMCO equipment, so on the head side I'm probably more configured like a 67. I had the same vacuum block on the manifold.
OK, we need to define some terms. "IMCO" stands for IMproved COmbustion. What that really means is Ford very carefully tuned the carb and distributor, and added or retuned a hot air riser mixer to the air cleaner. What it means, really, is "Very well tuned compatible components allowing the engine to pass emission standards". The smog system you have removed is what Ford called the "Thermactor" system, which pumps clean air into the exhaust ports to ensure more complete burning of exhaust, allowing the engine to pass emission standards.
My distributor vacuum advance is hooked up the same, albeit with a 1/4" rubber hose.
PCV is same.
Not sure what DCVC stands for, but I'm gonna guess it's the vacuum retard for the distributor? I've capped that at the distributor (inner port) and no longer use it.
In the 1970's roughly one billion high school kids disconnected or removed the Distributor Vacuum Control Valve, because It's Smog Equipment That Kills Performance. Nothing could be further from the truth. The DVCV senses coolant temperature at the thermostat. When coolant reaches 220°F, the valve opens, exposing the vacuum advance diaphragm to manifold vacuum, increasing the advance, which in turn causes the engine to idle faster, which spins the fan and water pump faster, which cools the engine below 220°F (hopefully). I suggest you return this safety feature to functionality.
Is that trans line really correct? It looks out of place to me, but I'm no expert by any means.
Oddly yes, it is.
For the brake booster, I see that port is blocked and the photo is not of a power brake car. Would that have been a 3/8 rubber hose to the booster or some sort of steel line?
My recollection is the line out of the booster valve to the transmission is smaller diameter than the brake booster line.
My vacuum block was rotated the other way (180°) with the threaded port facing forward, so the steel line comes to the front a little before going over the valve cover, much like in the pic 22GT posted. Now it's just an elbow because I'm not using any more than the threaded port. I've seen this pic before and it baffles me, but only because I'm trying to learn and understand this.

Also, not sure I wanna open the can of worms with the whole IMCO routings, so would it be more appropriate to be asking about 67 configurations?
The routing for 67-68 should be pretty much the same, unless you have a Thermactor, which you don't.

Your distributor vacuum-
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Discussion Starter #7
Just goes to show you learn something new every day!

I was not aware IMCO and Thermactor were two separate entities, I thought they were interchangeable terms referring to the smog system. Now that I understand a little better, I mostly have an IMCO setup I think:
  • Autolite C8DF-D distributor with dual advance (mechanical and vacuum) and dual vacuum (advance and retard, retard plugged)
  • Heat riser rube and shroud to match (need to check if waxstat is actually working, adjusted for only cold air at the moment)
  • Autolite 1100 w/ SCV (yes I know it shouldn't have an SCV unless paired w/ Load-O-Matic, new 1100 is on it's way from Champion w/o SCV, yes I know it won't run right w/o the correct match, chasing actual performance issues is its own separate task for me...)
Sadly mine never had the DVCV, but I think I see where there's a plug on the thermostat housing for it. I will look into installing it. Did that roll out with IMCO or Thermactor system, or did they all come together at once? For further info, it's originally an early 68 (Dec 67 build) Colorado car, and is still in Colorado. With the current cold temps, would you expect coolant to reach 220 thus activating the DVCV?

Finally, I was following right along about the trans line until I suddenly wasn't haha. You indicated my original statement about the 2 port check valve going to manifold and trans line was correct, but you also said the odd trans line in Woodchuck's photo was correct. It's got to be one or the other, right? I know I'm missing something.

Thank you guys so much for your help, I really appreciate it!
 

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The replacement DVCV is widely available. It was introduced slightly in 1967, and across the board in 68, to replace the earlier system that opened a valve on the carb or intake that dropped vacuum levels and increased idle speed.

The feature functions mainly in stop and go traffic. Leaving the car running in the driveway could easily do it, too.

Here's a couple more vacuum tube photos. The steel line for the top of the trans was the same either way, but fed by the booster instead of the tube on the engine. Note the rubber anti-rattle tube has been moved by someone, you can see the correct location as a clean area at the rear of the valve cover.

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