valk

1941 dual main Carters

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On 1/3/2020 at 12:06 PM, Matt Harwood said:

I used the Uni-Syn on my carbs and found it very useful. What my ear told me was pretty close turned out to be WAY off. The device is cheap, easy to use, and ingenious. It really made a difference.

 

6-6-19-9.thumb.jpg.4c70dc9d3df94c68253c789d8ebc5985.jpg  6-6-19-11.thumb.jpg.2046b05eff53ff418db91518b30b1615.jpg

Matt, do you have 2 Uni-Sync tools or just one to set the throttle valves. Also nice headers, homemade? And is that the original weighted flapper spacer under the rear carb?

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One is all that is required, move it from carb to carb, and back again as necessary.

 

Jon.

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No Peter our carb arms are identical. Just install it and see how it drives and if you still think its weird put lengthen it. You couldn't possibly be using up half the travel. When you drive it the linkage feels exactly the same. 

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59 minutes ago, pont35cpe said:

Matt, do you have 2 Uni-Sync tools or just one to set the throttle valves. Also nice headers, homemade? And is that the original weighted flapper spacer under the rear carb?

 

Made them myself:

 

That's the original flapper, but the flapper has been removed. It's just a spacer now. There are details in that same thread, which is the entirety of the work I've done so far on my Limited.

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Ok I'll give it a go tommorrow. Everything is hooked back up, pre-flight check list completed and she's ready to fire up. I rigged a choke heat tube from a section of brake line that probably works but ultimately I want to come up with a more elegant solution. I also still have to "alter" the air cleaner slightly so it seats properly on the back carb.  I'll get back to ya....can't thank you guys enough for your help. 

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On ‎1‎/‎3‎/‎2020 at 1:06 PM, Matt Harwood said:

I used the Uni-Syn on my carbs and found it very useful. What my ear told me was pretty close turned out to be WAY off. The device is cheap, easy to use, and ingenious. It really made a difference.

 

6-6-19-9.thumb.jpg.4c70dc9d3df94c68253c789d8ebc5985.jpg  6-6-19-11.thumb.jpg.2046b05eff53ff418db91518b30b1615.jpg

 

I have one of those.  I used it to balance the carb on my Corvairs years ago.  Works good.

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FFFuuuuudge. Ignition on, pedal depressed, no juice to the starter.  So I moved the wires from the front carb switch to the rear carb switch and she engaged so I guess the switch on the front carb, the one I just got, is bad. Of course, it worked last week when I stuck it on but not now.   Which is easier, rotating the carbs I just put on or swapping out the starter switches??  And on my birthday too....and its snowing like hell here...should have stayed in bed. 

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A visit from Murphy on your birthday!  I have only a rudimentary understanding of what you're doing here and the accelerator-activated starter on my car has been disabled, so this may be completely off base.  But is it possible that the linkage you have set up is no longer fully opening the front carb when the pedal is depressed and therefore not activating the starter switch on the front carb?  I'm only suggesting this because, despite Murphy's Law, it seems unlikely that the switch on the front carb would have failed after it was working last week.

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A visit from Murphy on your birthday!  I have only a rudimentary understanding of what you're doing here and the accelerator-activated starter on my car has been disabled, so this may be completely off base.  But is it possible that the linkage you have set up is no longer fully opening the front carb when the pedal is depressed and therefore not activating the starter switch on the front carb?  I'm only suggesting this because, despite Murphy's Law, it seems unlikely that the switch on the front carb would have failed after it was working last week.

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Thanks Neil. I agree it's very weird the switch would work one day and not the next.  I'll fiddle with it today and swap carbs if I can't get the front switch to work. I'm on my own here...

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1 hour ago, valk said:

Thanks Neil. I agree it's very weird the switch would work one day and not the next.  I'll fiddle with it today and swap carbs if I can't get the front switch to work. I'm on my own here...

That switch is a simple device with a plunger spring and ball. I would give it a few taps first but it might be sticky or have some grime on the contacts. It is very easy to take apart and clean and does not use a diaphragm or any delicate parts that will be harmed. You can also swap the parts from on carb to the other. Neils advice regarding linkage is irrelevant as long as you can actuate the floor switch which Im sure you can. The Carter switch I find works better then the Stromberg switch and its not rocket science to open it up.   

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Peter, the copper contacts in the switch could be the problem. It would be easier to remove the one hold down screw of each switch and swap them. I can send one if you need it. Tom

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Thanks again Lawrence and Tom for helping me out. I'll try removing the switch and cleaning the contacts. If that doesn't work, I'll swap switches and take it from there. I'm so damn close...until some thing else pops up...

Peter

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You can also use a jumper wire across the terminals on the switch to trigger the starter manually if you're just testing and tuning. I've done that in a pinch when the car wasn't behaving or I was alone.


Did you install the carburetor you bought on the front or back? It sounds like you put the new carb on the front and moved your original one to the rear position, correct? Perhaps swap them back and all will be well?

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Just removed both switchs (didn't know it was so easy), cleaned them up and reinstalled the front switch. Still no dice. I jumped the terminals and she fired. I then removed the switch and looked down the switch cavity and observed the ball in the bottom while activating the throttle and there was no movement. For the switch to work, something has to push the ball, which in turn pushes the contacts so they align and make a complete circuit but, again, nothing is pushing the ball when the gas pedal is depressed.  Nothing happens in the switch cylinder when the throttle is engaged.  I'm going to try the other switch to test this theory - the other switch will most likely not work either since nothing is pushing the contacts to align.  So I think both switches work fine. My problem is in the carb itself. The other option is to swap carbs so my working start circuit is in the front but it bugs me I can't get the switch to work. As always, I could be full of it but this is what I've observed.  Your ideas are most welcome. 

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Peter, ball should be rolling free, when its low in the hole its in the start position Try this, with bearing in hole put the first piece(piston/metal, w/formed end) in the hole (long end at the bottom), then use a pencil or something to push firmly on the back of the piston, then turn the throttle valve, you should feel movement at the piston. If this works, problem is in the electrical part not the mechanical part of the switch.

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I know you're tired of hearing from me but here it goes...once again my initial diagnosis was bogus.  Tried the above and found both switches are good. Problem was/is in the short carb-to-carb linkage.  It wasn't allowing the front carb to fully engage. Back on track now and waiting for my hands to thaw before starting her up. Owning an old car is truly a humbling experience.  Thanks for hanging in with me. 

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2 hours ago, valk said:

Problem was/is in the short carb-to-carb linkage.  It wasn't allowing the front carb to fully engage.

 

Ahah!  I had a feeling that was the problem.

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So the short carb-to-carb rod has to be installed on the outside of the carb linkage mounting "arms" or else the rod and arm will hit on the front carb and limit the travel of the rod, preventing the starter from engaging.  I remounted the rod on the outside of the arm and everything works great.  I fired it up this morning and it started easily and ran great in my garage with the exception of the idle being too high. The front throttle stop screw is all the way out (the rear screw removed) so I have to lower the idle by some other method. Below are quotes by both Lawrence and Jon addressing this issue but I'm not totally clear of the method described. I know the idle can be lowered by adjusting the idle screws but I thought the best optimal setting of the screws was to maximize the idle speed.  Not so? 

I need to syn the chokes with a Uni-sync gizmo, alter my air cleaner and I'm essentially done. 

Peter

 

Hi Jon, I recently swapped my matching Strombergs on my 41 Century for matching 528S Carters and indeed they work better. My question is how does one achieve a lower idle if your already completely  backed out on the idle screw. My idle is still a touch to high and having read through the Carter adjustments in the workshop manual I am still clueless as to what path to take. Thanks Lawrence


If the throttle positioner screw (a.k.a. curb idle screw) is backed out so it is not touching, and the idle mixture control screws are turned in until thumb tight, the engine should stall. They are several "happy medium" combinations of the screws to acquire the desired idle.

 

J

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Make sure that the throttle blades are actually closing. It is possible to have the rods adjusted such that they don't allow the throttles to close even if you have the screws backed all the way out. This is how mine were at first. As Lawrence points out, you really need to make that pedal-to-front-carb rod as long as possible--I think I only have 3 or 4 threads in each end with a majority of the heim joint threads showing. That rod being a little too short would certainly prevent the throttles from closing all the way. Disconnect the throttle rod and see if it will idle properly. In fact, maybe do most of your tuning that way so that you know when you reconnect it if things get wonky, that's the problem.

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Good idea so I disconnected the long rod,  ran it and it was the same, too high.  Also made sure the other carb-to-carb rod was not the cause. My long rod is extended absolutely the most it can be, only 2 or 3 threads grabbing on each end and, being short, the pedal spring actually pulls the carb throttles tightly closed . 

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Also make sure the choke cam is not holding the throttle open.

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I think you need different linkage, but in the meantime, remove the linkage from one carb, loosen ALL of the nuts attaching both carbs to the intake, and with a helper, push both carbs toward each other and then tighten all of the nuts. There is a tiny bit of play in the carb throttle body to the studs. You might get enough slack to do some testing; but I would highly recommend redoing the linkage. Multiple carb linkage is very easy to fabricate. If you wish, give me a call during normal business hours, and I will explain. Then, if you wish, you can type it in this thread.

 

Jon

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Actually, now that I think about it, the pedal-to-front-carb rod being too long is what would push the throttle blades open. Sorry about the confusion!

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