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I am about to replace my intake and carburetor on my 78 f250 with a stock 460. I would like to eliminate as many of the vaccum lines as possible. My question is of both the lines on the water neck and the ones attached to the valve cover in the picture. Is it fine to leave those off the new intake and just plug the hole in the water neck? The new carburetor will be a Holley 750cfm single inlet vaccum secondaries with electric choke. The intake will be a weiand stealth.
The device in the water neck is called a ported vacuum switch - it controls the flow of vacuum based on coolant temperature.
Why are you looking to re-do your vacuum lines? Is there a problem you're trying to correct? They're there for a reason... Are you aiming to delete emissions control systems, or ... ?
If you're just looking to do clean-up, I'd suggest re-routing or using silicone line in colors you like rather than just indiscriminate removal. The lines are there to control various aspects of the engine calibration for specific reasons. Just removing them is not, generally speaking, a good idea, unless you know what you're getting rid of and why.
Truck changed hands a couple of times before I bought it, so I'm not positive on all the details (could be mild rebuild). It has stock heads and intake with a Holley dual fuel carb. There are vac lines for advance, transmission and brake booster. That's it.
If you're just looking to do clean-up, I'd suggest re-routing or using silicone line in colors you like rather than just indiscriminate removal. The lines are there to control various aspects of the engine calibration for specific reasons. Just removing them is not, generally speaking, a good idea, unless you know what you're getting rid of and why.
The top line just goes to the base of the carburetor. It could stay if I could find a way to have just one fitting. Since the bottom two just go to another one of these valve things on the intake.
What about the thing attached to the valvecover bolt?
I also wanted to remove since a PO removed several things and now I have random caps on vaccum lines and It would look much better without the vaccum caps everywhere.
Truck changed hands a couple of times before I bought it, so I'm not positive on all the details (could be mild rebuild). It has stock heads and intake with a Holley dual fuel carb. There are vac lines for advance, transmission and brake booster. That's it.
Even with a mild rebuild theres not much difference as far as the engines so removing these lines should not have any ill effects. March: your engine runs fine without the lines right?
A ported vacuum switch (the device in the coolant jacket) switches vacuum based on temperature. A two-port variety would be simply on/off (below a set temperature, off; above it, on). A three-port variety switches which of the top/bottom ports the middle port sees.
There are several possible applications of this: one is for control of overheating - a 3-port PVS with a ~230F temperature will have the top (normally open) port going to ported vacuum, the bottom (normally closed) port going to manifold vacuum, and the center (controlled device) port going to, e.g., the distributor vacuum advance. This would have the functionality of switching the spark advance from ported to manifold vacuum if the engine gets too hot, which would keep the timing advanced at idle, thus increasing the idle speed, and correspondingly, the water pump speed, which would serve to cool the engine down. Other applications have similar, but different, functionality.
A lot of 2-port switches will be set up at, say, 100F, such that something (e.g. EGR) will be disabled at cold-start, but enabled once the engine warms up a bit.
Again, before just wholesale deleting things, I'd figure out what they do and decide whether that's a desirable thing..,
A ported vacuum switch (the device in the coolant jacket) switches vacuum based on temperature. A two-port variety would be simply on/off (below a set temperature, off; above it, on). A three-port variety switches which of the top/bottom ports the middle port sees.
There are several possible applications of this: one is for control of overheating - a 3-port PVS with a ~230F temperature will have the top (normally open) port going to ported vacuum, the bottom (normally closed) port going to manifold vacuum, and the center (controlled device) port going to, e.g., the distributor vacuum advance. This would have the functionality of switching the spark advance from ported to manifold vacuum if the engine gets too hot, which would keep the timing advanced at idle, thus increasing the idle speed, and correspondingly, the water pump speed, which would serve to cool the engine down. Other applications have similar, but different, functionality.
A lot of 2-port switches will be set up at, say, 100F, such that something (e.g. EGR) will be disabled at cold-start, but enabled once the engine warms up a bit.
Again, before just wholesale deleting things, I'd figure out what they do and decide whether that's a desirable thing..,
If that water jacket is supposed to have a line to the vac advance on the dist. Then it definitely is not hooked up correctly. It runs fine not being hooked up.
I'm not sure if you meantioned in your last post of what the diaphram attaced to the valve cover is for? It looks to me like the lines pretty much go from the intake back to the intake.
March: If you are getting 8mpg I better take these things off. I'm getting 5-6mpg right now.
I was giving one example of what a 3-port PVS can be used for. There are various other applications too. Again, you need to understand what it's doing before you decide what to make it stop doing.
I was giving one example of what a 3-port PVS can be used for. There are various other applications too. Again, you need to understand what it's doing before you decide what to make it stop doing.
I've got all the lines/switches on my mostly OE 400. As posted, they are there for a reason. Seems like the best approach is either 1) keep it stock style and take care of the lines and switches (replacements are available) 2) plan to re-do everything including carb setup and distributor curve. In between... simply deleting some lines, may lead to problems and hurt drivability, mileage and engine life.
I've got all the lines/switches on my mostly OE 400. As posted, they are there for a reason. Seems like the best approach is either 1) keep it stock style and take care of the lines and switches (replacements are available) 2) plan to re-do everything including carb setup and distributor curve. In between... simply deleting some lines, may lead to problems and hurt drivability, mileage and engine life.
Well the lines in question that I am looking to remove have nothing to do with emissions so the curve of the distributer should not be effected. I am replacing the intake and carb tomorrow.
Well the lines in question that I am looking to remove have nothing to do with emissions so the curve of the distributer should not be effected. I am replacing the intake and carb tomorrow.
Sounds like you are most of the way to replacing everything. If it originally had EGR, the distributor curve will be tuned accordingly. May tend to ping without the EGR and need adjusted.
PS: you can probably get it down to 3 lines 1) distributor to ported vacuum on the carb 2) power brakes to full carb or manifold vacuum 3) PCV to carb.
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