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#41
10-23-2018, 10:18 AM
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So the donor carb didn't work very well, it ran worse. It spit, sputtered, popped, and idled rough. It didn't have a choke so that was part of the problem when I first started it but it didn't idle well after it warmed up. I'm going to put my old idle pick up tubes and power piston spring back in mine and see how that goes. I got the new throttle plates without the holes in them and tried to put them on last night but all 4 screws broke off in the shaft and I can't get them out. I also ordered a distributor tune up kit. I'm at a complete loss.
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#42
10-23-2018, 12:00 PM
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Did the throttle blade screws turn at all?
Threads get peened/bradded, from the factory, to keep the screws from coming out. Some more than others. I've had to file the threads flush with the shaft, on some, before they would screw out. Looks like yours has enough threads hanging out the bottom to grab with keen nose pliars and screw them out the bottom. If the only problem with this carb was idle, not sure I would change anything but throttle blades. And find some one that knows about the mixture screws. Something would be bad wrong if a weaker power piston spring changed how much idle fuel the carb has. Piston at its lowest supplies enough fuel through the jets to run at highway speeds. May need to get part numbers off the top, main body and base plate to see if this is even "one" carburetor and not a frankenstien put together. Kenth or Cliff can probably help with that. Clay |
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#43
10-23-2018, 12:56 PM
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The screws backed out a bit then broke. There’s not enough sticking out anymore to grab. I tried but only got one out. If I start grinding them they will be flush with the shaft with nothing sticking out. I was going to try to drill into one and see if I could use a screw to screw it back through but the drill bit broke because it’s so small.
At this point I’m trying everything I can think of. The carb was working fine before I rebuilt it for my upgraded cam and compression. The only thing I can’t change back is the idle bypass and idle down channels which were both made bigger. The problem went beyond idle. I thought I had it adjusted over the weekend and took it for a drive. When I got the end of the street and stopped, it died. I could barely get it started again and had to limp it home because it wouldn’t stay running. Sounded like it was starving for fuel, but my plugs indicate I’m running rich. I haven’t been able to get a hold of Cliff since he recommended enlarging the tubes and bypass a couple weeks ago. I’ve been looking online for a new refurbished one. I really don’t want to spend $400 though. Sent from my iPhone using Tapatalk |
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#44
10-23-2018, 06:52 PM
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There’s no way to get these screws out without drilling them out. If I do that I’m going to have to tap the shaft and try to find screws to fit. Or try to find the primary and possibly secondary shafts at a junkyard.
Sent from my iPhone using Tapatalk |
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#45
10-23-2018, 09:29 PM
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you have to grind the back of the screw flush with the shaft in order to get it to come out without breaking. Sometimes I've had to soak the throttle body in kroil or other penetrating oil to get them to come loose.
at this point I would grind all the broken screws flush and see if I can get the shaft to come out of the throttle body. Then just replace the throttle shaft with a donor from a very similar carburetor.
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I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 |
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#46
10-23-2018, 10:18 PM
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Quote:
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#47
10-24-2018, 01:09 AM
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I got one out after breaking it off on the last carb I did but I felt very lucky to get it drilled without damaging the shaft threads. It took a lot of patience. I drilled it as close to the edge as possible and used a sharp punch to break the remaining screw threads out. Like I said, I felt very lucky to get it out without ruining the threads.
If it had been more than one, I think I would have shopped a new shaft as has been suggested. For future reference, I always use a Dremel with a carbide bit to grind those staked threads flush with the shaft. Also, NEVER try to force one of those screws. As you know, they'll break off in a heartbeat! If it offers much resistance to turning, you haven't ground the staked area off enough.
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Greg Reid Palmetto, Georgia |
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#48
10-24-2018, 02:38 AM
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Quote:
Late to the thread, but thought I'd mention that main jets don't have anything to do with the idle circuit. You could put brass plugs in the jet holes or install 120 jets and the static idle won't be affected.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 Catalina Safari Wagon. |
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#49
10-24-2018, 10:43 AM
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Quote:
Glue the punch to the screw, see if the bond is strong enough to turn the screws. You'd want to glue to the "bottom" of the screw, so that you're removing from the under side. |
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#50
10-24-2018, 01:18 PM
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#51
10-24-2018, 02:01 PM
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Sometimes a small carbide in a pin vise will drill a small screw out. Or maybe use a stud welder to weld a pull stud to the screw and then try to twist it out. Beyond that, the throttle shaft is a kaploosh. (Which is the sound it makes when you throw it in the lake)
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I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 |
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#52
10-24-2018, 04:37 PM
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Super glue is great in tension but poor in shear.
George
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"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
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#53
10-24-2018, 05:18 PM
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Wonder how difficult it would be to make new shafts ... probably a standard size shaft, with a flat milled, then drilled and threaded and the linkage staked on the end. Bet I could make one.
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#54
10-24-2018, 06:01 PM
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Quote:
This right process is you Take a file and file off the "staked over" portion of each throttle blade screw until the screw is flush with the throttle shaft. Then you take a GOOD screwdriver with a proper tip for the screw to engage in and carefully remove each screw. Replace the blades with non drilled blades and either install new screws and stake them in place or use loctite on the shortened screws. With the loctite they will be just fine. After the first screw broke off, the screw was trying to tell you something. Most would have stopped after the second screw broke off. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
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#55
10-24-2018, 09:31 PM
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#56
10-25-2018, 03:11 AM
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It's been a while but I remember reading to loosen the threads by tightening, not by trying to back them out. Then continue to tighten and intentionally twist the head off. I think the idea was to then grab the protruding peened stub with needle nose and rotate them ccw to pull them through - no filing.
Is this folklore? |
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#57
10-25-2018, 03:23 AM
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May not be folklore and it might work but I couldn't intentionally break those screws off.
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Greg Reid Palmetto, Georgia |
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#58
10-25-2018, 09:22 AM
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At Times
Quote:
The screw 'has to' turn in some before you cut or pop the head off. Once the blade is out of the way..the exposed end may need file work before trying to screw it through . Sharpened jaws on mini vise-grips works good for this. Clay |
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#59
10-25-2018, 10:57 AM
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I always used a Dremel tool to grind the ends of the screw. they then usually back out with some care. Afterwards I then replace them with new screws...2-56 thread, IIRC and peen them down.
George
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"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
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#60
10-25-2018, 11:01 AM
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My throttle shaft problem is solved. I picked up a 71 Pontiac 455 Q-jet 7041262 yesterday for $100. Thanks Paul! I'm going to clean it up and put the new parts from the old carb in it. I'm not going to open up any bypass air channels or idle channels since the old one ran worse after I did that. I'm going to give it a basic rebuild and hope for the best. I can get the correct divorced choke and not have to worry about the modified one coming apart anymore. When I started rebuilding the motor back in June I said I was going to do it right and not cut corners to make things work. Getting a Pontiac Q-jet with the correct choke was on the list.
The last piece for the upgraded distributor will be here today so I can put it back together tonight. I already have it apart and cleaned up waiting to go. The shaft was really gunked up with greasy sticky crud. It spins much more freely now. I should be doing some tuning on Saturday. Btw...I have Olds Q-jet that needs a new primary throttle shaft for sale...LOL It ran good before the rebuild and had good response. The old parts will go back in and I'm still going to look for a shaft and get it in working order again. |
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