78 351m vacuum lines
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From: Phoenix, AZ
78 351m vacuum lines
New to this - I have a 78 F150, 351m, 2150 carb, 4x4 - I need help with vacuum lines. I tried a 4v carb and never could get it to work so I went back to the 2150. The only problem I lost the vac line drawing I made. I've got it running but not strong like it was - hesitation at low RPM's. I found the original Ford drawing of the 351m online - big help but does not show everything. The 2150 has 3 vac ports - V (back), E (front) and S (side). I know where V&S go but the drawing does not show the E port, if in use, or the PCV. I know my original set up had the PCV going to the back of the carb - the E port I can not remember. Any help would be greatly appreciated!
Thank You!
Thank You!
More Turbo
Joined: Nov 2004
Posts: 590
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From: in the woods of Maine!
I think most people on here do what I do. Only use the vacuum hose for the adv. on the distributor, and the big one for the PCV. And if your one of those guys running an auto, you'll have one going down to your modulator on the tranny.(tells the tranny how much load is on the engine)
As long as it fits onto the fitting it will be okay. All vacuum lines(except one) run off intake vacuum. Except for the vacuum advance on the distributor. That runs what is called ported vacuum. Ported vacuum doesn't pull vacuum at idle, only when you start to crack the throttle will it pull vacuum. It is the one pointing straight out the left side of the carb.
As long as it fits onto the fitting it will be okay. All vacuum lines(except one) run off intake vacuum. Except for the vacuum advance on the distributor. That runs what is called ported vacuum. Ported vacuum doesn't pull vacuum at idle, only when you start to crack the throttle will it pull vacuum. It is the one pointing straight out the left side of the carb.
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From: Phoenix, AZ
351m vac lines
Thanks for your help. My 78 truck is all original - EGR, ETC. so I have been trying to fix what I messed up when I tried a different carb. No vac diagram under the hood but I was smart enough to make a drawing first. Never could get it to work so I went back to the 2150. Just one problem I lost my drawing. I had to try to hook the lines up from memory. I'm afraid age has taken a toll and my lack of experience does not help either. The good news I have been learning alot - like your suggestion - since I found this site. Thanks again!
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I have the same truck. The tranny, power brake, and EGR all work from the vacuum tree on the intake.
Carb ports:
The port on the passenger side-front of the carb goes to the distributor. The big port on the drivers side rear goes to the PCV on the oil filler cap. There's a port on the pass side top under the airhorn that connects to the intake stove pipe...that's the long metal tube coming from the intake with a rubber hose on the end. The short "S" shaped stovepipe tube screws into the choke with a fitting. The only other port is the vent on the front that's supposed to go to the charcoal canister...but I don't have one so it's disconnected.
Carb ports:
The port on the passenger side-front of the carb goes to the distributor. The big port on the drivers side rear goes to the PCV on the oil filler cap. There's a port on the pass side top under the airhorn that connects to the intake stove pipe...that's the long metal tube coming from the intake with a rubber hose on the end. The short "S" shaped stovepipe tube screws into the choke with a fitting. The only other port is the vent on the front that's supposed to go to the charcoal canister...but I don't have one so it's disconnected.
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From: Phoenix, AZ
Thanks!
Danny,
Thank you, I appreciate your info! I have to make a few changes and that should take care of the problems. With no vac diagram under the hood I was smart enough to make a drawing before I changed carbs. I never could get the 4v to work so I went back to the 2150. Unfortunately I lost my drawing and had to rely on my memory. At my age it is not as sharp as it once was and my lack of experience didn't help either.
Thanks again,
Mark
Thank you, I appreciate your info! I have to make a few changes and that should take care of the problems. With no vac diagram under the hood I was smart enough to make a drawing before I changed carbs. I never could get the 4v to work so I went back to the 2150. Unfortunately I lost my drawing and had to rely on my memory. At my age it is not as sharp as it once was and my lack of experience didn't help either.
Thanks again,
Mark
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Joined: Oct 2009
Posts: 188
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I know what you're saying. I'm no mechanic either.
I can disconnect something, answer the phone, then I can't remember where I disconnected the "thing" from...haha.
I started snapping pictures with my digital camera before removing, unplugging, or disconnecting ANYTHING! I also use a roll of masking tape and a sharpie pen to tag wires and hoses. I'm sure seasoned mechanics would snicker at my overkill, but half the stuff I disconnect? I don't know what it does anyway.
So, I BETTER know how to hook it back up...haha
I can disconnect something, answer the phone, then I can't remember where I disconnected the "thing" from...haha.
I started snapping pictures with my digital camera before removing, unplugging, or disconnecting ANYTHING! I also use a roll of masking tape and a sharpie pen to tag wires and hoses. I'm sure seasoned mechanics would snicker at my overkill, but half the stuff I disconnect? I don't know what it does anyway.
So, I BETTER know how to hook it back up...haha
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