ArdWrknTrk Posted July 31 Share Posted July 31 Based on his pics the bottom port of the 3 port VCV seems to be open... might explain why things get worse when hot as there would be no vacuum advance after things get hot. Jeremy, if that is the case, please connect that bottom port of the VCV straight to the intake manifold ... Okay, now I'm looking at this... .... and don't understand how he expects to switch from one vacuum source to the other if there's no line there (crossed out) But that still doesn't explain the pulsing vacuum as the engine warms up. This VCV isn't supposed to open until the engine starts overheating (above 225F or so) If it were the blue VCV that controls EGR and opens as the engine reaches operating temp (like 185-190F) I could grasp why it would make a difference The pulsing thing, I still need to get a handle on. Is it at 16"hg and spikes up? Or is there a pressure spike (vacuum disappears) Link to comment Share on other sites More sharing options...
Bullnose Gator Posted July 31 Author Share Posted July 31 Okay, now I'm looking at this... .... and don't understand how he expects to switch from one vacuum source to the other if there's no line there (crossed out) But that still doesn't explain the pulsing vacuum as the engine warms up. This VCV isn't supposed to open until the engine starts overheating (above 225F or so) If it were the blue VCV that controls EGR and opens as the engine reaches operating temp (like 185-190F) I could grasp why it would make a difference The pulsing thing, I still need to get a handle on. Is it at 16"hg and spikes up? Or is there a pressure spike (vacuum disappears) Jim, yep, I understand the VREST is the little blue piece I added to the line. And yes, I added the plastic elbow connecting the center port of the VCV and the vac advance line to the distributor, just because it was there to begin with, I wasn't expecting it to change anything. Vivek, I'm probably confusing what manifold ports are. Can you define the carb ports below for me? The big one with the arrow to the metal line is the one the pcv was hooked up to, which I detached to hook my vacuum gauge to. Let me know if I'm supposed to be hooking the gauge to the little one below it instead. Also, which one of these should I run the bottom port of the vcv to? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted July 31 Share Posted July 31 Jim, yep, I understand the VREST is the little blue piece I added to the line. And yes, I added the plastic elbow connecting the center port of the VCV and the vac advance line to the distributor, just because it was there to begin with, I wasn't expecting it to change anything. Vivek, I'm probably confusing what manifold ports are. Can you define the carb ports below for me? The big one with the arrow to the metal line is the one the pcv was hooked up to, which I detached to hook my vacuum gauge to. Let me know if I'm supposed to be hooking the gauge to the little one below it instead. Also, which one of these should I run the bottom port of the vcv to? The PCV pipe needs to go to the big nipple in the base* flange, like you had it The (code red) manifold vacuum should be coming from one of the vacuum trees like your diagram shows, but could go to the small nipple to the left of PCV. The timed vacuum port (E) by the choke would be for EGR and should be capped if you're not using it. Link to comment Share on other sites More sharing options...
Bullnose Gator Posted July 31 Author Share Posted July 31 Speaking of vrest...thanks for explaining what it does. Now, can you confirm where it is? Based on the diagram, I think it's the top port on the yellow vcv valve pictured below, but not sure. I did more tinkering/learning last night, and tried to run vac lines to the dist adv from one of the manifold ports through the vcv/vrest. The yellow lines on the diagram are what I was trying to do, the blue lines in the pic are what I did. Let me know if the two line up... It idled better, but still bad. The vacuum gauge (hooked to the carb manifold port this time) read around 42 inches. I turned the vac adv clockwise until it was closed, then went 2 turns counterclockwise at a time, it didn't idle good anywhere along the way. Thanks. I ran the bottom vcv port to the carb port on the left of the pcv port, and hooked the gauge to the carb port below the pcv port, (I'm assuming it's the port on the egr spacer). See the orange line in the pic below: It started and idled pretty good. Here's the gauge about 30 seconds after cranking it, needle still a little jumpy: After a few minutes, I decided to try and check the timing. I don't know if it was just a coincidence or not, but a few seconds after I clamped the timing gun leads to the battery, the idle changed in an instant. Immediately the gauge dropped to the pic below. That was right around 5 minutes after starting it: Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted July 31 Share Posted July 31 Thanks. I ran the bottom vcv port to the carb port on the left of the pcv port, and hooked the gauge to the carb port below the pcv port, (I'm assuming it's the port on the egr spacer). See the orange line in the pic below: It started and idled pretty good. Here's the gauge about 30 seconds after cranking it, needle still a little jumpy: After a few minutes, I decided to try and check the timing. I don't know if it was just a coincidence or not, but a few seconds after I clamped the timing gun leads to the battery, the idle changed in an instant. Immediately the gauge dropped to the pic below. That was right around 5 minutes after starting it: Where is your ignition timing set? 8,10,12° BTDC??? How is it with the vacuum advance connected? Link to comment Share on other sites More sharing options...
viven44 Posted July 31 Share Posted July 31 Jim, yep, I understand the VREST is the little blue piece I added to the line. And yes, I added the plastic elbow connecting the center port of the VCV and the vac advance line to the distributor, just because it was there to begin with, I wasn't expecting it to change anything. Vivek, I'm probably confusing what manifold ports are. Can you define the carb ports below for me? The big one with the arrow to the metal line is the one the pcv was hooked up to, which I detached to hook my vacuum gauge to. Let me know if I'm supposed to be hooking the gauge to the little one below it instead. Also, which one of these should I run the bottom port of the vcv to? Bottom port of the vcv needs to go straight to intake manifold your intake should have a 3 or 4-way tree... hook it up to that... see yellow arrow below Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted July 31 Share Posted July 31 Bottom port of the vcv needs to go straight to intake manifold your intake should have a 3 or 4-way tree... hook it up to that... see yellow arrow below It's 4-way in the front intake runner. You can see it in his routing diagram. But it doesn't really matter, as long as it's full manifold vacuum. Link to comment Share on other sites More sharing options...
viven44 Posted July 31 Share Posted July 31 It's 4-way in the front intake runner. You can see it in his routing diagram. But it doesn't really matter, as long as it's full manifold vacuum. Yes Jim, I agree. Mine is actually hooked up to the Edelbrock full-manifold port. I saw some ambiguity in the statement "I ran the bottom vcv port to the carb port on the left of the pcv port".... I don't know that carb.... so I just wanted to keep it simple. As long as he is not hooked up to 'E' which is the ported if I am not mistaken, I think it should be fine. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted July 31 Share Posted July 31 Yes Jim, I agree. Mine is actually hooked up to the Edelbrock full-manifold port. I saw some ambiguity in the statement "I ran the bottom vcv port to the carb port on the left of the pcv port".... I don't know that carb.... so I just wanted to keep it simple. As long as he is not hooked up to 'E' which is the ported if I am not mistaken, I think it should be fine. You say you have a half dozen 4180's! http://www.garysgaragemahal.com/uploads/6/5/8/7/65879365/laughing-25-x-25_orig.gif They're pretty much all the same. The one on my 85 GT had 4 corner idle, but these trucks ones don't. Anyway, in the pic above you can see E uncapped Here's all the ports in the carb and spacer: Link to comment Share on other sites More sharing options...
Bullnose Gator Posted July 31 Author Share Posted July 31 Speaking of vrest...thanks for explaining what it does. Now, can you confirm where it is? Based on the diagram, I think it's the top port on the yellow vcv valve pictured below, but not sure. I did more tinkering/learning last night, and tried to run vac lines to the dist adv from one of the manifold ports through the vcv/vrest. The yellow lines on the diagram are what I was trying to do, the blue lines in the pic are what I did. Let me know if the two line up... It idled better, but still bad. The vacuum gauge (hooked to the carb manifold port this time) read around 42 inches. I turned the vac adv clockwise until it was closed, then went 2 turns counterclockwise at a time, it didn't idle good anywhere along the way. To remove any doubt, I moved the bottom port of the vcv from the carb port to a port on the exhaust manifold tree. It seemed to run better there too. I marked the crank pully at 0, 10, 20, as best I could (i need to get a more visible marker) and with the timing gun set at 0 it was reading around 20, but looked like it was bouncing a little back and forth. I ended up turning the dist vac advance with the Allen wrench all the way clockwise (is that fully closed?) And that was the best it ran. The 20 mark stabilized much better under the timing gun. I then adjusted the idle screw to get to 800 rpms. I did NOT remember to clamp the dist vac adv hose, per the ford instructions below during this process though, sadly. I'll have to try again, I assume. Here's the gauge after those adjustments: Link to comment Share on other sites More sharing options...
Recommended Posts