The Ford Barn

jeepguy1948 · 06-16-2023, 06:48 PM

I am working on a 51 F1 for a friend and I am confused. I should say that the fuel pump was removed and a cover plate installed in its place (50 years ago). I always use a vacuum gauge to test manifold vacuum when tuning an engine. In this case the problem is that I cannot find a place to connect the gauge. The only port is right below the carb and it seems to be a Venturi type of vacuum (It slowly goes UP as the motor is accelerated, not DOWN as is normal. I’m assuming that that is the location where the distributor advance was connected when the engine had it’s original Stromberg 97 (it now has a Holley 94 and the dist advance is connected to a port on the carb). Please tell me what is wrong with this situation, I’m baffled.

tubman · 06-16-2023, 07:23 PM

Sounds like nothing is wrong, unless you have faulty components.

It seems like someone installed an electric fuel pump when the origiinal pump was removed, but that's a common procedure.

1.The engine does not have a Stromberg 97 as original (unless someone
has done some strange things with the engine).

2. The Holley 94 with the port on the middle back of the carburetor is the
correct carburetor for this truck; the engine uses Ford's "Load-A-Matic"
advance system in the distributor that requires connecting to that port.
The proper carburetor for this truck shoukd be marked "8RT" (like the heads).

3. The vacuum port below the carburetor (given that is in the intake manifold)
is the vacuum wiper port and should react conventionally.

It sounds like someone has gotten in there and changed all kinds of stuff based on incorrect knowledge.

I hope it wasn't you, but I'm not sanguine about that.

(Please feel free to ignore all of this if the truck now has a pre-war 21 stud engine.)

jeepguy1948 · 06-16-2023, 10:53 PM

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Distributor is stock with a Pertronix module. Motor is 51 Merc 30 over. Yes, the port I was referring to is in the manifold directly below the carburetor, I will have to try a different vacuum gauge to confirm what I am seeing or not. I have been around this truck, and in fact helped put this motor in 50 (yes five-zero) years ago, and at that time I also converted it to the electric wipers (you are have to excuse the fact that after 50 years and many, many cars and trucks, I don’t remember how the wipers were plumbed). I do not believe that I am in over my head, if I was I would not be asking questions. The motor is not original to the truck, it is a Merc that we swapped in (freshly rebuilt by a nationally known V8 specialist). Truck was driven approx 1,000 miles (right up until my buddy became a daddy (surprise!) and parked 40 plus years ago. I was asked to attempt to bring the truck back to life a year ago. In the past year I have gone thru the diff. The brakes, the trans, the distributor which I set timing at total advance of 28 degrees, the steering box, rebuilt the springs, replaced the shocks, and on and on. I now have the engine running after very very carefully prepping it for a first start in 40 years, replaced the fuel pump (with the same Carter that I installed 50 years ago). I do not have it on the road yet because I just finished the installation of the diff and driveline today. Motor is running quite nicely although it currently has open tube headers because we are waiting our turn at the exhaust shop. Headers are Red’s tube headers with 1.75 collectors. The entire exhaust system will be 1.75 with Hooker Aerochamber (sp?) which I have good experience with. So, I have to ask my original questions again (in the other thread).

06-16-2023, 06:48 PM	#1
jeepguy1948 Senior Member Join Date: Jan 2022 Posts: 756	Manifold Vacuum, 2 questions I am working on a 51 F1 for a friend and I am confused. I should say that the fuel pump was removed and a cover plate installed in its place (50 years ago). I always use a vacuum gauge to test manifold vacuum when tuning an engine. In this case the problem is that I cannot find a place to connect the gauge. The only port is right below the carb and it seems to be a Venturi type of vacuum (It slowly goes UP as the motor is accelerated, not DOWN as is normal. I’m assuming that that is the location where the distributor advance was connected when the engine had it’s original Stromberg 97 (it now has a Holley 94 and the dist advance is connected to a port on the carb). Please tell me what is wrong with this situation, I’m baffled.

06-16-2023, 07:23 PM	#2
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,446	Re: Manifold Vacuum, 2 questions Sounds like nothing is wrong, unless you have faulty components. It seems like someone installed an electric fuel pump when the origiinal pump was removed, but that's a common procedure. 1.The engine does not have a Stromberg 97 as original (unless someone has done some strange things with the engine). 2. The Holley 94 with the port on the middle back of the carburetor is the correct carburetor for this truck; the engine uses Ford's "Load-A-Matic" advance system in the distributor that requires connecting to that port. The proper carburetor for this truck shoukd be marked "8RT" (like the heads). 3. The vacuum port below the carburetor (given that is in the intake manifold) is the vacuum wiper port and should react conventionally. It sounds like someone has gotten in there and changed all kinds of stuff based on incorrect knowledge. I hope it wasn't you, but I'm not sanguine about that. (Please feel free to ignore all of this if the truck now has a pre-war 21 stud engine.) Last edited by tubman; 06-16-2023 at 07:31 PM.

06-16-2023, 10:53 PM	#3
jeepguy1948 Senior Member Join Date: Jan 2022 Posts: 756	Re: Manifold Vacuum, 2 questions Sponsored Links (Register now to hide all advertisements) Distributor is stock with a Pertronix module. Motor is 51 Merc 30 over. Yes, the port I was referring to is in the manifold directly below the carburetor, I will have to try a different vacuum gauge to confirm what I am seeing or not. I have been around this truck, and in fact helped put this motor in 50 (yes five-zero) years ago, and at that time I also converted it to the electric wipers (you are have to excuse the fact that after 50 years and many, many cars and trucks, I don’t remember how the wipers were plumbed). I do not believe that I am in over my head, if I was I would not be asking questions. The motor is not original to the truck, it is a Merc that we swapped in (freshly rebuilt by a nationally known V8 specialist). Truck was driven approx 1,000 miles (right up until my buddy became a daddy (surprise!) and parked 40 plus years ago. I was asked to attempt to bring the truck back to life a year ago. In the past year I have gone thru the diff. The brakes, the trans, the distributor which I set timing at total advance of 28 degrees, the steering box, rebuilt the springs, replaced the shocks, and on and on. I now have the engine running after very very carefully prepping it for a first start in 40 years, replaced the fuel pump (with the same Carter that I installed 50 years ago). I do not have it on the road yet because I just finished the installation of the diff and driveline today. Motor is running quite nicely although it currently has open tube headers because we are waiting our turn at the exhaust shop. Headers are Red’s tube headers with 1.75 collectors. The entire exhaust system will be 1.75 with Hooker Aerochamber (sp?) which I have good experience with. So, I have to ask my original questions again (in the other thread).