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Carb Linkage
Hi Guys: Having trouble with my carb linkage. I used the mechanical linkage from AC. I have 2 750CFM Hollies on my 64 427. When i press the gas pedal, its not returning all the way. I thought it was the return spring so i drilled another hole in the universal linkage and gave it alot more tension. I am running a dual return spring mounted on the firewall connected to the passenger side of the carburater.
There seems to be alittle loosness. So i tightened up the linkage rods but that just made my gas pedal not function at all. Any suggestions. I have uploaded pictures of my linkage in my gallery Automan |
Is this a new setup that you have just installed or has it been on for a while and you are just now having problems with it.
Terry |
I have a similar setup but with a different configuration with the return spring on the opposite side.
http://www.clubcobra.com/photopost/d...tor_pics14.JPG http://www.clubcobra.com/photopost/d...tor_pics11.JPG http://www.clubcobra.com/photopost/d...tor_pics15.JPG |
It appears the linkage design is different with the return spring bracketry on the opposite (drivers) side of what you have configured. From what I can see from your gallery pics you are running both carbs in primary status?
http://www.clubcobra.com/photopost/d...427_SO0010.JPG http://www.clubcobra.com/photopost/d...9442700061.JPG http://www.clubcobra.com/photopost/d...4dual_quad.jpg |
Automan, I have the same set up as Lineslinger.
Take the springs off and make sure none of the linkage is binding up and moves very freely. It looks like the leverage is at a disadvantage with those strong springs on the universal linkage that ties the two carbs together. If you don't have any binding I would put the springs on the driver side like lineslinger. http://www.clubcobra.com/photopost/d...m/DSC02144.JPG The linkage from your firewall is similar to mine. http://www.clubcobra.com/photopost/d...m/DSC02147.JPG |
Just looked at my linkage and I noticed where your rod attaches to the lever on the driver side is to far forward.
You not having two four carbs changes the connection point on the carb pushing the lever farther forward which might cause a problem. The rod from the pedal to the firewall pivot is also on a pretty extreme angle. Mine is straight. I will take some pictures of my set up and post them when i get a chance. |
Thankyou all for your responses. Here are some answers to your questions. This is all new. I havn't yet tooken it for its first run because of this problem.
You said that it looks like i am running it in my primary only. Newbe here. What do you mean. I notice that the diaphrams are connected together. My points distributor has two outlets. I though thats where both diaphrams get connected. I see that you all have your diaphrams connected together. If that is so do i plug up the ones coming from the single points distributer. So with the firewall linkage bracket. When the accelerator pedal is in it's home position, should that bracket be facing straight down instead of pointing alittle forward like mine is? I see no one is using a universal connection like i am. I should probably try and find and buy a origional linkage. I will see if i can find a place to mount the spring on the other side. I really dont want to loosen of a manifold bolt to mount the bracket. I am afraid of creating a leak. Thaks again. Keep it coming. I could use all the help i can get. Summer is creeping by and i still havn't felt it out on the road. Automan |
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I think what Lineslinger meant by "primaries" was that you are running your carbs in a "synchronized" arrangement (where the primaries open in unison or together) rather than the "progressive" arrangement (where the front primary opens about 1/3 before the back primary starts opening) that was stock.
The above suggestions are good ones, I agree that the angles on the arms are a little extreme. Also, on the passenger side, the little "P-shaped" link is on the outside of the bellcrank, but the stock diagram shows it on the inside. There is a rod that sticks out of the arm it is hooked to that will snag the short rod on opening and prevent it from returning to the closed position. You need to put the short rod into the bellcrank arm on the carb side of the arm. Here are a couple of shots of my installation (if I can figure out how to insert photos). Never mind, I can't figure it out... |
I just noticed that i dont have a butterfly flap on one of my carbs. This is going to get rough. OK one problem at a time.
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OK: i let go of the return springs and started to see where it was catching. Found acouple of problems. First was the base that goes between the carbs. One end was bent where it was causing restriction in the arm. Straightened it out and it had a noticable improvment. Next was that P shaped arm. I reversed it and i was off to the races. Full return on the gas pedal. No sticking. But, now, dont know what i did to change it but now the carbs are leaking at both bowls where the gas lines are connected too. I pulled them apart and actually had a spare seal and replaced it. Still leaking. Can i use tephlon tape to wrap around the fittings or will the gas eat it up.
Automan |
Teflon might be a temporary fix if it is leaking between the nut and the bowls, since that would seal the threads between the nut and the bowls, but if it is leaking between the nut and the flared inlet pipe it likely won't work, as that flare fitting relies on the nut holding the two flared fittings together for a seal. I'm not sure how you would fix the leak at the flare. You need to tighten the nut to the bowl (gently, don't overtighten), and then HOLD that nut with a wrench while you tighten the flare nut. If not, the inlet pipe will twist when you tighten it against the snug nut, then when you let go of the flare nut, the inlet nut will back off and leak...
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I think i might of overtightened both inlet nuts before the flare nut. Thats where it is leaking. Thats why both are leaking. Im wondering if i might of cracked both bowls.
Automan |
There should be a fiber washer betweem the bowl and the fitting.
No teflon tape.I doubt you cracked the bowls unless you really wrenched on them. mr0077 is correct. About the flare fittings. Back it up with a wrench. Check the surface of the flare fittings. No dope, thread compound, sealer or teflon tape. It shoud seal without this. Trust me on this, I am a plumber. Sounds like you are on the right track with the linkage binding problem. |
I'd expect stripped threads (not a real good thing) before cracked bowls IF you damaged the bowls...either way it means new bowls I think.
I would bet that the nuts backed off when you tightened the flare nut on the inlet pipes. Get a backup wrench, hold the bowl inlet nut, loosen the flare nut, tighten the bowl nut firmly then hold in place while you tighten the flare nut...don't let the bowl nut turn in the tightening direction when you tighten up the flare nut, and see if that fixes it. Let us know. |
Just a test to see if I can attach photos...
http://www.clubcobra.com/photopost/d...0/DSC00038.JPG And another http://www.clubcobra.com/photopost/d...0/DSC00038.JPG |
Well, i went out and bought some new seals and nuts for the inlets. Still linking. I screwed up the bowls. No doubt they are both stripped. So now, i need to figure out what am i going to do. Do i try and re tap them or just see if i can get new bowls. This really sucks. OK, cryings over. The serial numbers on my carbs are:
6R2762 List-3310-2 C757 6R2762 List-3310-2 C642 Anybody have any idea where i can get two bowls. This is really starting to turn out to be some kind of comedy act. The Wife is pissed. Quote" you mean to tell me after all that money we might not be able to drive it this summer!!!!!" As the Cobra wrold Turns. Automan |
Sorry to hear that, and surprised too. I would try teflon before I gave up on the bowls, though. Be careful not to get any loose tags of tape where they will go into the carb...bad potty.
I'm not aware of a helicoil-type repair for the bowls...go to this link http://www.holley.com/TechService/ and tell them your situation...they will sell the parts or tell you how to get them. I got some impossible OEM carb and fuel line parts for a '66 427 'Vette restoration from them quick and cheap. |
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