BigBrother-84 Posted August 8, 2023 Author Share Posted August 8, 2023 Awesome that you were able to get the correct restrictor. Looking forward to the driveability report when you get Big Bro tuned up! Thanks Jim, I too am happy to have find it. Bought it at Greensales, they had more than 40 in stock! They shipped immediately, really happy about their service. There were 3 other stores on Rearcounter claiming they had 1 to 3 in stock, so in fact there’s not a lot available. About installation, I found this on web: « That vacuum restrictor can be installed any direction. It isn't a check valve, it's just a pinhole opening for slowly bleeding air.» Anyone has a comment about this? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 8, 2023 Share Posted August 8, 2023 Thanks Jim, I too am happy to have find it. Bought it at Greensales, they had more than 40 in stock! They shipped immediately, really happy about their service. There were 3 other stores on Rearcounter claiming they had 1 to 3 in stock, so in fact there’s not a lot available. About installation, I found this on web: « That vacuum restrictor can be installed any direction. It isn't a check valve, it's just a pinhole opening for slowly bleeding air.» Anyone has a comment about this? Suck it and see... No, I don't believe they have any direction. (at least mine doesn't) Link to comment Share on other sites More sharing options...
BigBrother-84 Posted August 8, 2023 Author Share Posted August 8, 2023 Suck it and see... LOL! I already did it before posting and well, the air seems to flow equally in either direction. Looks that it can be installed in any ways. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 8, 2023 Share Posted August 8, 2023 Awesome that you were able to get the correct restrictor. Looking forward to the driveability report when you get Big Bro tuned up! (Jim - He's gonna be pleasantly surprised. But let him find out on his own. ) Link to comment Share on other sites More sharing options...
BigBrother-84 Posted August 9, 2023 Author Share Posted August 9, 2023 (Jim - He's gonna be pleasantly surprised. But let him find out on his own. ) Gentlemen, trying to clarify the Ported Vacuum Switch (3 port) behavior. Between the two scenarios below, which one is right? Scenario 1 (3 stages): 1- Engine cold: Completely closed, no vacuum so no ignition advance. 2- Engine warm: Port 1 (with the restrictor) connects to port D (distributor), a little timing advance is allowed. 3- Engine getting hot: The switch flips from Port 1 to Port 2 (unrestricted) and provides full manifold vacuum to port D (distributor), so you get more advance, the water pump and fan run faster, allowing the engine to cool down. Scenario 2 (2 stages): 1- Engine cold and warm: Port 1 (with the restrictor) connected to port D (distributor), allowing little timing advance. 2- Engine getting hot: The switch flips from Port 1 to Port 2 (unrestricted) and provides full manifold vacuum to port D (distributor), so you get more advance, the water pump and fan run faster, allowing the engine to cool down. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 9, 2023 Share Posted August 9, 2023 Gentlemen, trying to clarify the Ported Vacuum Switch (3 port) behavior. Between the two scenarios below, which one is right? Scenario 1 (3 stages): 1- Engine cold: Completely closed, no vacuum so no ignition advance. 2- Engine warm: Port 1 (with the restrictor) connects to port D (distributor), a little timing advance is allowed. 3- Engine getting hot: The switch flips from Port 1 to Port 2 (unrestricted) and provides full manifold vacuum to port D (distributor), so you get more advance, the water pump and fan run faster, allowing the engine to cool down. Scenario 2 (2 stages): 1- Engine cold and warm: Port 1 (with the restrictor) connected to port D (distributor), allowing little timing advance. 2- Engine getting hot: The switch flips from Port 1 to Port 2 (unrestricted) and provides full manifold vacuum to port D (distributor), so you get more advance, the water pump and fan run faster, allowing the engine to cool down. Scenario 2 is almost correct. The system is there to keep the engine within operating parameters... Cold and at temperature restricted vacuum reaches the distributor. Only when the coolant temperature far exceeds normal operating temperature should the thermal vacuum valve switch ports and apply unrestricted manifold vacuum. Ports in my yellow valve shift well above the boiling point of water at STP. (perhaps 220~225°F) Maybe Ralph or Gary knows what temp yours shifts at Link to comment Share on other sites More sharing options...
BigBrother-84 Posted August 9, 2023 Author Share Posted August 9, 2023 Scenario 2 is almost correct. The system is there to keep the engine within operating parameters... Cold and at temperature restricted vacuum reaches the distributor. Only when the coolant temperature far exceeds normal operating temperature should the thermal vacuum valve switch ports and apply unrestricted manifold vacuum. Ports in my yellow valve shift well above the boiling point of water at STP. (perhaps 220~225°F) Maybe Ralph or Gary knows what temp yours shifts at So, there’s alway a bit of vacuum applied to the distributor diaphragm. I suppose that at idle, the succion is really low, so almost no timing advance. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 9, 2023 Share Posted August 9, 2023 So, there’s alway a bit of vacuum applied to the distributor diaphragm. I suppose that at idle, the succion is really low, so almost no timing advance. Jim - I don't know what temp causes the valve to open and don't see anything in the catalog that says. Jeff - As long as your vacuum cannister doesn't have a leak you will eventually get full vacuum even with the restrictor in. All it does is slow transitions down, not reduce them. If you have a vacuum gauge you can prove that to yourself by pulling the line off the distributor and placing it on the gauge. When the engine starts you'll see the vacuum come up slowly to full manifold vacuum - assuming that your system uses manifold instead of ported vacuum. (Looking at your diagram I see that it goes to the carb, but don't remember if that is ported or manifold. Surely manifold or the engine couldn't speed up at idle if it got hot.) To explain how this works lets discuss a parallel system - electricity. The equation E=IR gives the voltage drop across a resistor which is directly dependent on the current through the resistor. Zero current gives zero voltage drop. But your restrictor is equivalent to a resistor. When the engine starts there is a little bit of air in the vacuum cannister in the distributor, so there's a bit of flow (current) through the restrictor as the air is sucked out, so there's a "vacuum drop" across the restrictor. But when the air is fully out there's no flow and, therefore, no vacuum drop across the restrictor. Link to comment Share on other sites More sharing options...
81-F150-Explorer Posted August 9, 2023 Share Posted August 9, 2023 Jim - I don't know what temp causes the valve to open and don't see anything in the catalog that says. Jeff - As long as your vacuum cannister doesn't have a leak you will eventually get full vacuum even with the restrictor in. All it does is slow transitions down, not reduce them. If you have a vacuum gauge you can prove that to yourself by pulling the line off the distributor and placing it on the gauge. When the engine starts you'll see the vacuum come up slowly to full manifold vacuum - assuming that your system uses manifold instead of ported vacuum. (Looking at your diagram I see that it goes to the carb, but don't remember if that is ported or manifold. Surely manifold or the engine couldn't speed up at idle if it got hot.) To explain how this works lets discuss a parallel system - electricity. The equation E=IR gives the voltage drop across a resistor which is directly dependent on the current through the resistor. Zero current gives zero voltage drop. But your restrictor is equivalent to a resistor. When the engine starts there is a little bit of air in the vacuum cannister in the distributor, so there's a bit of flow (current) through the restrictor as the air is sucked out, so there's a "vacuum drop" across the restrictor. But when the air is fully out there's no flow and, therefore, no vacuum drop across the restrictor. I know they are color coded by temp. Here is a list. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 9, 2023 Share Posted August 9, 2023 I know they are color coded by temp. Here is a list. Great info Ralph! And it seems I have been giving bad information about how mine (yellow) functions. My apologies to Jeff who had it right with his second scenario, and anyone who took my word for gospel. Link to comment Share on other sites More sharing options...
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