Man without clue takes apart engine. Has many questions. Needs YOUR help.

[Mechanon]

First off, thanks anyone who takes the time to read and reply. These forums have been helpful already.

Starting with the vitals: 1975 F150 - 67k orig - 360/390 FE - Motorcraft 2150 D5TE-AAA - C6 Auto - Factory AC - (aftermarket?) Cruise control.

When I picked it up, it ran - but not well. I'm a welder by trade, shadetree mechanic. I can get by pretty well with the right guidance and resources. That said, this old ford is a totally new experience for me as far as timing, carb tuning, and vacuum systems. I do own the shop manuals for this truck and they do NOT cover the vacuum system in detail. They also reference a lot of maintenance procedures they assume the reader already knows, so they don't always explain them very well, if at all. So here's where I am as far as stuff I've DONE:

Maintenance things: New plugs, cap + rotor, air filter, fuel filter (at carb), radiator & heater hoses, PCV + hose, temp sending unit, radiator cap, oil + filter change, topped off some fluids (coolant & 2 quarts of trans fluid) and rebuilt the carb including accelerator pump. New valve cover gaskets (they still leak of course)

And some of the more questionable "non-maintenance" things:

- Removed smog pump, bypass valve, thermactor headers (plugged holes with 1/2"-20 set screws + RTV)

- Removed EGR valve (left the carb spacer in place, and blanked off the valve flange with a piece of 1/4" stainless plate + gasket).

- Ran vacuum from the spark port on the carb STRAIGHT to the distributor (bypassing the manifold temp switch and left out the vacuum delay valve).

- Hot air tubes were broken off the choke, so I plugged the hole in the choke housing, and capped the fresh air port on the air horn. Ordered an electric choke kit (not here yet)

- When I pulled the carb off to rebuild, the idle mixture screws were backed out 7.5 turns if you can believe it. Now I have them set at about 3 turns out.

So here's where I am right now. I'll say it's a miracle that it even fired up at all after I had my way with it, and I am thankful for that. Now I'm at the part where I realize I have NO IDEA what 'tuning' progression I should be following to get this thing back on the road. But I assume getting the vacuum lines sorted out is top priority so my first question is this:

1a) Besides the choke pulloff port and spark port at the base of the the carb, what are the other engine vacuum sources and where can I find them.

1b) Which systems absolutely require system vacuum to function properly, and which do not? My intake manifold is just a huge mess of temperature switches and hoses going everywhere. I want to eliminate / consolidate everything I can.

After that's all sorted out, do I go onto timing or carb tuning? The issue I'm running into with the carb is everywhere I look says that "x and y have been set from the factory and are not to be adjusted" and sometimes will say "If they have been adjusted, reset them to factory spec" But I can't find any of these factory specs anywhere... Even in the shop manuals.

My mission here is basically to trim the fat and get this thing running with the least amount of unnecessary crap under the hood as possible. As long as it runs and shifts right, heat & AC work, power brakes & steering - that's all I want. It's not going to be a hotrod by any means, but I want a clean engine bay with the least amount of things I'll need to constantly be troubleshooting on an old truck like this. It's smog exempt and that's one of the main reasons I bought it. All of the emissions crap is going in a box on the highest shelf in the garage.

[Mechanon]

When I rebuilt the carb, I noticed it seems like the accelerator pump piston might be shorter than the old one? leaving a gap between the piston and pump lever. Makes no difference which hole it's in on the overtravel lever. I've attached a video here.

https://www.youtube.com/watch?v=8S_mdzzvtZI

[Mechanon]

For setting the choke, he says in this turotial "The standard way I set the choke is to turn the choke cover until the top butterfly closes." I'm not sure what this means. The cover is just closed and I can only turn the cover a few degrees either way.

Here's another video - https://www.youtube.com/watch?v=knQvZxJb1dE

[Mechanon]

And here's a few videos showing the vacuum clusterfk I have going on right now. ANY help here would be MUCH appreciated.



1) https://www.youtube.com/watch?v=mcuEztsy_vY

2) https://www.youtube.com/watch?v=_9Vy8UaOTOk

3) https://www.youtube.com/watch?v=KLG4kffjmJU

[Mechanon]

Also the electric choke conversion just showed up in the mail. Instructions say to tap into the idle stop solenoid wire (which I don't have) but that any "12 volt service turned on and off by key" will do. SO what would be the most convenient 12v keyed source under the hood? (I thought I read that these used a 7v AC source off the stator but I guess I was wrong.)

[Ranchero50]

Where are you located?

Simplest concept per vacuum is to realize it's all doing the same stuff as an electrical system, only via vacuum. Per what you do and do not need, you need manifold vacuum going to the trans modulator. You need ported vacuum going to the distributor. You also need manifold vacuum going to the power brake booster.

Looks like you have vacuum going to a ported dash pot module on the throttle (tan round thing). I assume that's to keep the idle higher under no vacuum conditions. I'd adjust that away from the throttle if it's holding it open.

Per tuning, adjust the timing to @ 15` BTDC with the vacuum off. Then once fully warm you want the choke off far enough that the fast idle won't kick in and only then start dialing the idle mixture in. Scoop some exhaust and sniff it (same as scooping water onto your face). Fully warmed up you want it as non stinking as possible.

What you are going to find is some components might be tuned to run with all the junk attached and may run worse (think timing curves and any oddball ports on the carb).

Per the electric choke kit. Do you have a Duraspark module (Google it) or points? If points you'll need to find power from the key (not the coil '+'). If Duraspark, coil '+' should work.

[sargentrs]

First I would cap off and plug every vacuum line/port except the one to the spark port on the carb, the pcv valve on the valve cover, tranmssion line, and power brake booster if you have one. The smog stuff comes with a ton of vacuum lines and vacuum switches and unless it's all functional you don't want any of it. Then get a vacuum gauge and hook it up to intake manifold vacuum for tuning the carb and setting the timing. The goal is the highest steady vacuum reading you can get. Ideally 18-21Hg. Crank it up and set your idle screw on the carb for about 700rpm. Slowly turn in the mix screws until you get a steady vacuum reading, one at a time. Then reset your idle if necessary. Once that's steady move on to timing.

[Mechanon]

Where are you located?

Believe it or not, I'm in San Francisco. The fart eating prius driver capital of the world.

You need ported vacuum going to the distributor. You need manifold vacuum going to the trans modulator [and] power brake booster.

Thanks. Got the distributor hooked straight to spark port on carb. Where do I find manifold vacuum? Is there an actual manifold vacuum port on the intake manifold? I can't tell which one it would be, unless it's stuff way back behind the carb where I can't see. Do either of these things need to go through those vacuum temp switches on the manifold? Or can I hook them straight?

Looks like you have vacuum going to a ported dash pot module on the throttle (tan round thing). I assume that's to keep the idle higher under no vacuum conditions. I'd adjust that away from the throttle if it's holding it open.

I don't have that adjusted at all, it's just all the way backed off so it's not interfering with anything. As I understand it, it's (theoretically) to keep the throttle plates from snapping shut too quickly under deceleration and stalling the engine (rich condition?) but a lot of guys don't even run them. So after I get everything else all worked out, I'll see if I even need it.

Per tuning, adjust the timing to @ 15` BTDC with the vacuum off. Then once fully warm you want the choke off far enough that the fast idle won't kick in and only then start dialing the idle mixture in. Scoop some exhaust and sniff it (same as scooping water onto your face). Fully warmed up you want it as non stinking as possible.

Okay I'll try that with the timing. But I have no idea what the fast idle is, how it works or how to adjust it, or the choke, really.

Per the electric choke kit. Do you have a Duraspark module (Google it) or points? If points you'll need to find power from the key (not the coil '+'). If Duraspark, coil '+' should work.

Yeah I have an early duraspark (not duraspark II) if that makes a difference. Will the + on the coil still be fine?

[Mechanon]

First I would cap off and plug every vacuum line/port except the one to the transmssion line, and power brake booster if you have one.

Yeah that's the goal. So can I run that stuff straight off manifold vacuum without going through the vacuum heat switches? I also have that vacuum reservoir canister (coffee can) mounted next to the battery. Does anything actually require this to function?

The smog stuff comes with a ton of vacuum lines and vacuum switches and unless it's all functional you don't want any of it.

Yeah the smog components are gutted already, now just trying to figure out what hoses I can get rid of because I have a bunch of dead ends now.

Then get a vacuum gauge and hook it up to intake manifold vacuum for tuning the carb and setting the timing. The goal is the highest steady vacuum reading you can get. Ideally 18-21Hg. Crank it up and set your idle screw on the carb for about 700rpm. Slowly turn in the mix screws until you get a steady vacuum reading, one at a time. Then reset your idle if necessary. Once that's steady move on to timing.

So do you do all this after it's fully warmed up I take it? In park or does it have to be idle under load like in drive with the brakes set? You do the mixture before the timing then?

[sargentrs]

I also have that vacuum reservoir canister (coffee can) mounted next to the battery. Does anything actually require this to function?
That's part of the "evaporative emission system" also. It's purpose is to vent the gas tank, clean the fumes, and recycle them back through the carb. If you want to remove it, get a vented gas cap for your tank and plug the lines. If everything is hooked up and in decent condition you don't have to mess with it, it's just another air filter. However, you do need to vent your tank somehow.

So do you do all this after it's fully warmed up I take it? In park or does it have to be idle under load like in drive with the brakes set? You do the mixture before the timing then?

Yes, after you get it warmed up so you eliminate any gremlins that may be caused by your choke, or lack of. Set it while in park. Carb setting, timing, and carb idle all go hand in hand. Get the timing set close enough so it'll run without stalling, adjust the carb, tweak the idle, tweak the timing, adjust the carb, tweak the idle and so on. Adjusting one requires adjusting the other. Once you have it running smoothly in your driveway and you start it up, rev it, kill it and it starts up and revs up again, you're ready to work on the timing for driveability. Don't get all hung up on "factory settings". It's a 50 yr old truck, the factory settings are now just a suggestion. Every truck is different and it wants what it wants.

[sargentrs]

I also have that vacuum reservoir canister (coffee can) mounted next to the battery. Does anything actually require this to function?

That's part of the "evaporative emission system" also. It's purpose is to vent the gas tank, clean the fumes, and recycle them back through the carb. If you want to remove it, get a vented gas cap for your tank and plug the lines. If everything is hooked up and in decent condition you don't have to mess with it, it's just another air filter. However, you do need to vent your tank somehow.

So do you do all this after it's fully warmed up I take it? In park or does it have to be idle under load like in drive with the brakes set? You do the mixture before the timing then?

Yes, after you get it warmed up so you eliminate any gremlins that may be caused by your choke, or lack of. Set it while in park. Carb setting, timing, and carb idle all go hand in hand. Get the timing set close enough so it'll run without stalling, adjust the carb, tweak the idle, tweak the timing, adjust the carb, tweak the idle and so on. Adjusting one requires adjusting the other. Once you have it running smoothly in your driveway and you start it up, rev it, kill it and it starts up and revs up again, you're ready to work on the timing for driveability. Don't get all hung up on "factory settings". It's a 50 yr old truck, the factory settings are now just a suggestion. Every truck is different and it wants what it wants.

[Ranchero50]

As the choke closes for cold start it also bumps the idle speed up. That's the fast idle step. The fast idle works with the choke flap on the top of the carb to richen the mixture when cold. Look at the throttle shaft on the choke side and you'll see a linkage that has an adjustment screw that rides on a stepped cam. That's the fast idle. The step correspond to different RPM's per flap closure. It's all part of the tuning strategy you'll need to tweak to get the truck to start up cold and also idle hot.

Check the vacuum diagrams for you model. You should have manifold vacuum coming off the back of the carb or intake tree. Eventually you'll hit up some junk yard and pull the T off an earlier model to clean up the area. Per your temp switches, without knowing what they were controlling or what purpose they were controlling them, leave them unhooked. On a '75 the can may also just be a vacuum reservoir to keep all the emissions stuff working under low vacuum conditions.

[Mechanon]

I also have that vacuum reservoir canister (coffee can) mounted next to the battery. Does anything actually require this to function?

That's part of the "evaporative emission system" also. It's purpose is to vent the gas tank, clean the fumes, and recycle them back through the carb. If you want to remove it, get a vented gas cap for your tank and plug the lines. If everything is hooked up and in decent condition you don't have to mess with it, it's just another air filter. However, you do need to vent your tank somehow.

Ah, I actually have 2 cans. I think you're talking about the lower one which has 3 ports on it. One goes to the gas tank, the second goes to the top port on the carb (external bowl vent?) and the third I believe is... vacuum I guess. So yeah I suppose I can eliminate that, vent the tank with a vented cap, and vent the bowl to atmosphere.

The one I was talking about is mounted right against the battery and has a single inlet / outlet on it. It's completely empty (no filter or "charcoal" element so I assumed it was a reservoir. If I can confirm that neither the brake booster or transmission need this to function, I can eliminate that too.

So do you do all this after it's fully warmed up I take it? In park or does it have to be idle under load like in drive with the brakes set? You do the mixture before the timing then?

Yes, after you get it warmed up so you eliminate any gremlins that may be caused by your choke, or lack of. Set it while in park. Carb setting, timing, and carb idle all go hand in hand. Get the timing set close enough so it'll run without stalling, adjust the carb, tweak the idle, tweak the timing, adjust the carb, tweak the idle and so on. Adjusting one requires adjusting the other. Once you have it running smoothly in your driveway and you start it up, rev it, kill it and it starts up and revs up again, you're ready to work on the timing for driveability. Don't get all hung up on "factory settings". It's a 50 yr old truck, the factory settings are now just a suggestion. Every truck is different and it wants what it wants.

Cool, I'll spend some time on that. As far as factory settings go, I know they're not a hard and fast rule. It was just a reference point for me to start with, especially since the shop manuals reference them but don't actually give me the settings.

As the choke closes for cold start it also bumps the idle speed up. That's the fast idle step. The fast idle works with the choke flap on the top of the carb to richen the mixture when cold. Look at the throttle shaft on the choke side and you'll see a linkage that has an adjustment screw that rides on a stepped cam. That's the fast idle. The step correspond to different RPM's per flap closure. It's all part of the tuning strategy you'll need to tweak to get the truck to start up cold and also idle hot.

Yeah I guess that's all stuff I can tackle after the initial settings are done. Fortunately it doesn't get very cold here. 45f is probably the coldest the truck will see some mornings, and never below freezing. So the choke isn't as critical here as it would be in other places.

Check the vacuum diagrams for you model. You should have manifold vacuum coming off the back of the carb or intake tree. Eventually you'll hit up some junk yard and pull the T off an earlier model to clean up the area. Per your temp switches, without knowing what they were controlling or what purpose they were controlling them, leave them unhooked. On a '75 the can may also just be a vacuum reservoir to keep all the emissions stuff working under low vacuum conditions.

Yeah the vacuum diagrams are kind of difficult to find for my model somehow. I don't know what happened to the under hood one, and none of the ones I've found online seem to match what I have. So I'm just working with what I've got, which is very little.

[1972hiboy]

Good to see another bay area member. I know several iron workers. Went to high school with one who just works on the Golden Gate now.