The Quest for more power
- Thread starter subzali
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SteveH
Hard Core 4+
I cut 13 seconds off my FJ40's 0-60 time by installing a new 2F, years ago. I dropped from 39 to 26 seconds! Not many people can boast that they shaved 13 seconds off their 0-60.
Rezarf
Hard Core 4+
Tell me more of the paper clip trip. Can't I just have someone stomp on it and see if the secondaries are opening?
You have peeked my interest.
Rezarf
Hard Core 4+
I've got the smallest motor in my 40 than anyone...can I play?Mines even just a 1 barrel and an auto to boot!
Now thats funny!
My money is on wild rice.Drew, the secondary will only open when the primary is basically wide open, and it's vacuum-actuated. The actuation rod for the vacuum is on the front of the carb. You can take a paper clip and put it on that rod. Slide it up against the vacuum chamber, and if after driving around spiritedly you find that the paper clip has been pushed down about an inch then you will know that your secondary is opening.
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PhatFJ
Hard Core 4+
1975 FJ-40
Hey Matt, thanks for this great thread!! I am trying to learn the STOCK carb setup as well and this got me to go out and check my setup. I verified all the linkages and vacuum lines, put the paper clip on the front diaphragm linkage and took it for a drive, not only did it NOT move but the motor seems to decelerate when I floor it. So, I pulled the vacuum assembly and verified that it does work, blew into the port feeding the vacuum module and could hear it blowing into the carb body which I can only assume, this is where the vacuum is being drawn from (funny, my emission control repair manual does not even mention this module nor the secondary acceleration). I am at a loss as to why the secondary is not opening, everything seems to be correct. I had Kim push the throttle to the floor while I verified that the linkage IS free to move and open the secondary venturi, could it be that I am not drawing enough vacuum to open it? if so, why? it seems to drive just fine as long as I am not asking for full throttle..
One other thing, while checking the vacuum lines I pulled the throttle positioner diaphragm line and pulled vacuum on it, it does move but it does not hold vacuum at all with the linkages returning to their normal position almost immediately after drawing vacuum, again, my manual does not go into the operation of this unit only the complete circuit, is this supposed to hold vacuum and keep the linkage in position as long as vacuum is being applied?
as always, thanks for the help!!!
Brian
Hey Matt, thanks for this great thread!! I am trying to learn the STOCK carb setup as well and this got me to go out and check my setup. I verified all the linkages and vacuum lines, put the paper clip on the front diaphragm linkage and took it for a drive, not only did it NOT move but the motor seems to decelerate when I floor it. So, I pulled the vacuum assembly and verified that it does work, blew into the port feeding the vacuum module and could hear it blowing into the carb body which I can only assume, this is where the vacuum is being drawn from (funny, my emission control repair manual does not even mention this module nor the secondary acceleration). I am at a loss as to why the secondary is not opening, everything seems to be correct. I had Kim push the throttle to the floor while I verified that the linkage IS free to move and open the secondary venturi, could it be that I am not drawing enough vacuum to open it? if so, why? it seems to drive just fine as long as I am not asking for full throttle..
One other thing, while checking the vacuum lines I pulled the throttle positioner diaphragm line and pulled vacuum on it, it does move but it does not hold vacuum at all with the linkages returning to their normal position almost immediately after drawing vacuum, again, my manual does not go into the operation of this unit only the complete circuit, is this supposed to hold vacuum and keep the linkage in position as long as vacuum is being applied?
as always, thanks for the help!!!
Brian
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Wow, lots of questions Brian! First let me catch up with some more photos and then I'll try to address your questions as best as I have been able to find out.
First, these pictures show my old bracket, as removed, and Dean's new bracket installed. My old bracket has a clip that holds the speedo cable, Dean's doesn't, so I might still repair my old bracket and re-install it. I think this is because in some years (like '76) the speedo cable doesn't go straight to the t-case; it first goes to a secondary speedo that controls things like the EGR maintenance warning light.
First, these pictures show my old bracket, as removed, and Dean's new bracket installed. My old bracket has a clip that holds the speedo cable, Dean's doesn't, so I might still repair my old bracket and re-install it. I think this is because in some years (like '76) the speedo cable doesn't go straight to the t-case; it first goes to a secondary speedo that controls things like the EGR maintenance warning light.
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These pictures show the secondary diaphragm housing and actuating rod on the front of the carb. Snap the paper clip on the actuating rod like so, slide it up like so and if it actuates it will end up an inch or so down the rod
(disregard my disconnected vacuum line - I did that for picture clarity and reconnected it after the picture was taken)
(disregard my disconnected vacuum line - I did that for picture clarity and reconnected it after the picture was taken)
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These pictures show the lever attached to the primary butterfly. In the first picture, it's at rest (idle). In the second picture, this is about how far it was getting before I replaced my bracket on the firewall. Clearly the primary wasn't fully open and the secondary wasn't engaging. The third picture shows its correct position when the pedal is on the floor (after new bracket is installed) and the secondary is allowed to open. (it's the brightly illuminated lever near the bottom of the carb with the hole near the end).
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That seems weird Brian. In fact, I was crossing my fingers that my only problem would be the bracket on the firewall. I wasn't sure what to do if I fixed that and it still didn't work. The operation of the secondary isn't really covered in your Emissions manual, but the Engine FSM shows a cutaway schematic and shows how to disassemble the secondary diaphragm housing. The Haynes manual shows the cutaway schematic as well. The source of vacuum is just downstream of the venturis, and there appears to be an orifice in that location, so theoretically if the throttle plates are open, drawing air through the venturis and you are giving yourself enough duration to overcome the effect of the orifice, it should operate. The fact that you are experiencing a stumble or hesitation at WOT could be the culprit though. Have you done all of your basic checks? Vacuum leaks (vacuum readings), timing, valve adjustment, accelerator pump functioning properly? 1975 Cruisers will also have the auxiliary accelerator pump (AAP), so you will need to verify that that is working properly as well.
One other thing, while checking the vacuum lines I pulled the throttle positioner diaphragm line and pulled vacuum on it, it does move but it does not hold vacuum at all with the linkages returning to their normal position almost immediately after drawing vacuum, again, my manual does not go into the operation of this unit only the complete circuit, is this supposed to hold vacuum and keep the linkage in position as long as vacuum is being applied?
as always, thanks for the help!!!
Brian
Looking at the Emissions FSM to verify, I believe the TP diaphragm should hold its position while vacuum is being applied, because at idle it is the vacuum that keeps the TP diaphragm pulled away from the throttles, allowing them to close fully and allowing your idle circuit to function properly and for you to make adjustments to your carb properly. Sounds like you might need to find another TP diaphragm (I don't think they are rebuildable), or test your vacuum-producing equipment to make sure it's not leaking, giving you false results. Actually, the best check would be to let the engine idle and see if the TP diaphragm remains retracted.
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Rezarf
Hard Core 4+
Wow Matt, thanks for the pics bro, that really helps. I am going to see what I see later tonight if I can get my 
to stomp the pedal a few times.
to stomp the pedal a few times.
PhatFJ
Hard Core 4+
Thanks for the reply Matt!! I have done a complete tune on the 2F and like I say it does run really well as long as I am not asking it to produce power at full throttle, even the idle control seems to work well, when I come to a stop the idle is noticeably higher and I can hear it step down, so I am not convinced that the Throttle Positioner is not working properly. The PO had the carb rebuilt and I am not sure it was done properly and I think it was done with a low end rebuild kit as he did give me the box. This being said, I think I am going to remove the carb and totally go through it by the book. Any advise on rebuild kits? I did look at the kit that SOR sells, I do not know if there is the same kit available locally or not.. One other thing on the Throttle Positioner, the 2F manual does say to "connect hose to choke breaker diaphragm (throttle positioner) and suck the hose with mouth. The diaphragm should move. If not, replace it". Well if yours is like mine, it does move but it just does not stay in the position.. Don't know, my choke works well and idle seems to work well 
Thanks again bro!!
By the way GREAT PICS!!! I don't know how you get some of those shots, I could not get a camera in some of those positions..
Brian
Thanks again bro!!
By the way GREAT PICS!!! I don't know how you get some of those shots, I could not get a camera in some of those positions..
Brian
kurtnkegger
Rising Sun Member
Matt, my carb secondary is activated by a switch on the throttle when floored, and goes through the emissions computer that releases the vacuum. If you have yours freed of the computer, perhaps you aren't getting the vacuum you need when you need it...
...Well if yours is like mine, it does move but it just does not stay in the position.. Don't know, my choke works well and idle seems to work well
Brian,
I just did the mouth-vacuum test on my TP diaphragm this morning. It pulls back and stays back as long as I keep the vacuum applied. But at idle it's not engaged like I think it should be. Maybe my VSV is not working. Hm.
PhatFJ
Hard Core 4+
Hey Kurt, looking at my emission control for 1975. The throttle position switch (at full throttle) activates the "power valve control system (2f engine only)", this does have the computer, vsv, red thermo s/w and vacuum surge tank as part of the same system.. I went through this system as well using a vac gauge and dmm, pulled the red thermo s/w and tested it with hot water on the stove.
PhatFJ
Hard Core 4+
Keyster kits are pretty popular for carb rebuilds, but supposedly the Hygrade kit is better. You can buy either of them on ebay.
I have a pretty small camera I guess
Thanks Matt, I pulled the carb yesterday to look it over. I noticed that the spring at the end of the secondary shaft was not fully wrapped to the stop, thus not applying enough tension to the secondary TV shaft. I fixed this, took it for a drive and it seems to be better but still not the power I think it should have. I will do another paper clip test today. Hey, looking at the 2f manual this morning I noticed that there are 2 springs in the picture of the secondary diaphragm, I am curious if the one in mine is to heavy, not allowing the diaphragm to retract
I did look for the Hygrade 791b kit and could only fine it at Woody's $40.00 + $11.00 shipping 
Oh, I also pulled one of the carb mounting studs out of the manifold so I got to do a helicoil repair yesterday as well.. 
Are we having fun yet???