Hey y'all,
I'm new here my father just purchased a 1967 Shelby gt 500 its number 1776 its mean man ill tell ya. But one thing is the gas pedal does not go to the floor at all. I started to look at the throttle linkage for the duals and I noticed when I pushed the throttle as far as it would go the carbs would only barely crack open meaning when the gas pedal is down all the way and the carb linkage is down all the way the carbs aren't at WOT but the pedal is as far as it will go only about 2.5 inches down it has no travel. If I had to guess the man who owned this car before messed with the linkage so you could never take it to WOT so the gas pedal only goes down like 2.5 inches not to the floor. You see me and my dad wanna drive this thing so how do I adjust the linkage so I can actually achieve WOT and the pedal goes to the floor.
Thank y'all,
Air_drewdy
Quote from: Air_drewdy on July 27, 2024, 03:36:04 AMHey y'all,
I'm new here my father just purchased a 1967 Shelby gt 500 its number 1776 its mean man ill tell ya. But one thing is the gas pedal does not go to the floor at all. I started to look at the throttle linkage for the duals and I noticed when I pushed the throttle as far as it would go the carbs would only barely crack open meaning when the gas pedal is down all the way and the carb linkage is down all the way the carbs aren't at WOT but the pedal is as far as it will go only about 2.5 inches down it has no travel. If I had to guess the man who owned this car before messed with the linkage so you could never take it to WOT so the gas pedal only goes down like 2.5 inches not to the floor. You see me and my dad wanna drive this thing so how do I adjust the linkage so I can actually achieve WOT and the pedal goes to the floor.
Thank y'all,
Air_drewdy
A lot of things can happen in 57 years,and your car has been apart and modified several times in the last 20 years. At this point, you'll need to post pictures of the current throttle linkage setup in order for us to offer any assistance.
Bill
Quote from: Bill on July 27, 2024, 08:25:17 AMQuote from: Air_drewdy on July 27, 2024, 03:36:04 AMHey y'all,
I'm new here my father just purchased a 1967 Shelby gt 500 its number 1776 its mean man ill tell ya. But one thing is the gas pedal does not go to the floor at all. I started to look at the throttle linkage for the duals and I noticed when I pushed the throttle as far as it would go the carbs would only barely crack open meaning when the gas pedal is down all the way and the carb linkage is down all the way the carbs aren't at WOT but the pedal is as far as it will go only about 2.5 inches down it has no travel. If I had to guess the man who owned this car before messed with the linkage so you could never take it to WOT so the gas pedal only goes down like 2.5 inches not to the floor. You see me and my dad wanna drive this thing so how do I adjust the linkage so I can actually achieve WOT and the pedal goes to the floor.
Thank y'all,
Air_drewdy
A lot of things can happen in 57 years,and your car has been apart and modified several times in the last 20 years. At this point, you'll need to post pictures of the current throttle linkage setup in order for us to offer any assistance.
Bill
+1
Okay can do here are some pics of it. You may have to zoom in a little bit I'm sorry.
Sorry if they are of lower quality if you need better ones I'll take some pics today
A picture back near the firewall of the accelerator bracket where the carburetor accelerator rod connects would be helpful.
Only small pictures come up . Too small to make anything out. When downloaded and blown up they are too low of resolution.
Best of luck with it
The 67 500 uses the 427 2x4 linkage. That mounts the carbs backwards.
It can be problematic in that it does have the tendency of locking the throttles open at WOT.
It is original to the car but I actually have found that what is referred to as the "trans-am" linkage, which mounts the carbs forward, is much easier to maintain and eliminates the twisting that can jamb the original open.
Often previous owners attempted to "fix" the linkage "issue" after the first scare of locking it up at WOT.
Adjusting it isn't really complicated. It is a matter of starting at WOT and working backwards to ensure everything will completely close when you step off of the throttle.
In my view it is also advisable to put a secondary return spring in as insurance. Certainly all "track" tech inspections now require that.
The only thing that detailed pictures of your set up will show is what is not stock and/or what has been changed.
Although you would like to do this yourself, I'd advise you to seek out an experienced mechanic in this specific set up.
It may seem simple and quite docile at rest but so does a 2,500 pound block buster, until it goes off. You should know what you can touch and what you shouldn't. Experience helps there.
You do not want some hot dog green horn messing with it. It can be lethal.
Quote from: shelbydoug on July 28, 2024, 11:30:58 AMThe 67 500 uses the 427 2x4 linkage. That mounts the carbs backwards.
It can be problematic in that it does have the tendency of locking the throttles open at WOT.
It is original to the car but I actually have found that what is referred to as the "trans-am" linkage, which mounts the carbs forward, is much easier to maintain and eliminates the twisting that can jamb the original open.
Often previous owners attempted to "fix" the linkage "issue" after the first scare of locking it up at WOT.
Adjusting it isn't really complicated. It is a matter of starting at WOT and working backwards to ensure everything will completely close when you step off of the throttle.
In my view it is also advisable to put a secondary return spring in as insurance. Certainly all "track" tech inspections now require that.
The only thing that detailed pictures of your set up will show is what is not stock and/or what has been changed.
Although you would like to do this yourself, I'd advise you to seek out an experienced mechanic in this specific set up.
It may seem simple and quite docile at rest but so does a 2,500 pound block buster, until it goes off. You should know what you can touch and what you shouldn't. Experience helps there.
You do not want some hot dog green horn messing with it. It can be lethal.
Doug a good part of your well meaning post is likely way over the posters head in terms of understanding. I highlighted what I think is the most important part of your message relative to him. I would add that a picture of the bellcrank area which is where the throttle rod connects to the accelerator pedal bracket arm coming out of the firewall . The big block specific rod and how it is adjusted/threaded into the bellcrank is a typical problem area IMO.
Quote from: Bob Gaines on July 28, 2024, 11:52:43 AMQuote from: shelbydoug on July 28, 2024, 11:30:58 AMThe 67 500 uses the 427 2x4 linkage. That mounts the carbs backwards.
It can be problematic in that it does have the tendency of locking the throttles open at WOT.
It is original to the car but I actually have found that what is referred to as the "trans-am" linkage, which mounts the carbs forward, is much easier to maintain and eliminates the twisting that can jamb the original open.
Often previous owners attempted to "fix" the linkage "issue" after the first scare of locking it up at WOT.
Probably a three hour detailed instructional video is in order? Go get 'em Bob!
Adjusting it isn't really complicated. It is a matter of starting at WOT and working backwards to ensure everything will completely close when you step off of the throttle.
In my view it is also advisable to put a secondary return spring in as insurance. Certainly all "track" tech inspections now require that.
The only thing that detailed pictures of your set up will show is what is not stock and/or what has been changed.
Although you would like to do this yourself, I'd advise you to seek out an experienced mechanic in this specific set up.
It may seem simple and quite docile at rest but so does a 2,500 pound block buster, until it goes off. You should know what you can touch and what you shouldn't. Experience helps there.
You do not want some hot dog green horn messing with it. It can be lethal.
Doug a good part of your well meaning post is likely way over the posters head in terms of understanding. I highlighted what I think is the most important part of your message relative to him. I would add that a picture of the bellcrank area which is where the throttle rod connects to the accelerator pedal bracket arm coming out of the firewall . The big block specific rod and how it is adjusted/threaded into the bellcrank is a typical problem area IMO.
I agree but if my statement is over his head, then so are the terms bellcrank, etc.
I had to figure it out myself and I didn't like my hair just going grey. So locking up at WOT straightened that out and went straight to white.
If he is like me, he will take it all as a challenge call Shotgun and/or humbug and go straight to "fixin' it".
That's ok. He won't loose fingers doing that and will eventually come to the conclusion of "OH! THAT'S what you meant?"
In my case, the bellcrank was never an issue. The primary secondary shafts (got that?) would twist just enough so that the secondary carb would hang open.
If that linkage was built today, it would be all rod ends like you would do with Webers.
Probably a three hour instructional video is in order? Go get 'em Bob!
I robbed this picture from Drew's Air Fuel Spark FB Page; Might help in the discussion.
It pains me to see that the fuel log mounting tabs are tack welded instead of spot welded like the factory did them. Drew did a excellent job on the carb linkage. The tack weld is easily distinguished as different once mounted. I hope I am mistaken and the final product is spot welded like original.
Fuel log is not mine.
Linkage is.
I have a dozen videos on how to set up linkage. Not sure why it is so difficult honestly.
Quote from: Drew Pojedinec on August 19, 2024, 09:24:43 PMI have a dozen videos on how to set up linkage. Not sure why it is so difficult honestly.
Not everyone is on FB. Can you link a video here?
Sure but they are still hosted on fb, I don't have the time or energy to put them on you tube ir even my own afscarbs webpage
Here is me describing the ones I recently made.
Had like 250ish sets made.
https://www.facebook.com/AirFuelSParkTech/videos/293053707146788/
Here is one explaining new vs old parts and how to address the issues of them
https://www.facebook.com/AirFuelSParkTech/videos/684225393423782/
Throttle pin heights, also shows the different ones I make and how to install them
https://www.facebook.com/AirFuelSParkTech/videos/405586851015635/
And talking about low riser and medium riser stuff
https://www.facebook.com/AirFuelSParkTech/videos/1051529845375353/
I should really just make a post here linking a lot of my useful videos.
Or I should take a day off and upload them all to my webpage
Anyway, hope these are helpful and don't come across as spam or anything like that.
Drew
Thank you
Unfortunately for some like me, not all have access to that FB page. :'(
I just watched all of Mr. Pojedinec's video links and I don't even have a dual quad setup. But it was very interesting as well as entertaining to watch the minutiae of these carburetor setups. They really are works of art and he has mastery over their mechanisms. Thanks for the links. If I ever go for a setup on any of my cars, I am going to you, sir.