727 linkage adjustment

[Scotty]

I have a '68 383 w/ a Carter AFB and 727 trans, seems I am having difficulty getting the linkage adjusted correctly (no passing gear while driving, but shifts through the gears good) and now have some questions for all of you experts out there.

1) I am using a 2 barrel carb kick down linkage on what is now a 4 barrel set up, are the 2&4 bbl kickdown linkages different? (I know the throttle cable position is different, I have modified the throttle cable holder to keep the cable in line with the throttle arm on the carb)

2) Should the kick down arm on the trans be moving from the fully forward position to the fully rearward position in relation to the throttle lever movement? It seems like if I adjust the linkage to where the lever on the trans is fully forward with the throttle in the idle position, the lever will not be in the fully rearward position at WOT. From what I understand, the lever in the trans does not just control the passing gear function, but through its movement controls line pressure.

3) Is it ok to have the lever on the trans not move to it's fully forward position to achieve the fully rearward position at WOT?

Thank you all!!

Scott

 

[saforwardlook]

You probably should have the 4 bbl linkage for the correct throttle pressure under all conditions - I am just not familiar with the 68 setups per se. You will not have kickdown if the throttle lever does not go fully rearward at WOT. If you use your current linkage, then if you set the trans lever so you do get WOT, then you will have delayed normal driving upshifts - but this may be acceptable to you as long as the normal shift points are not too delayed. Without the correct linkage, you are trading off one against the other.

 

[Scotty]

You probably should have the 4 bbl linkage for the correct throttle pressure under all conditions - I am just not familiar with the 68 setups per se. You will not have kickdown if the throttle lever does not go fully rearward at WOT. If you use your current linkage, then if you set the trans lever so you do get WOT, then you will have delayed normal driving upshifts - but this may be acceptable to you as long as the normal shift points are not too delayed. Without the correct linkage, you are trading off one against the other.

Thank you for confirming my thoughts about the delayed shift points. The way I have it adjusted now is at WOT the trans lever is fully rearward, when the throttle is released the trans lever returns very, very close to the fully forward position. I haven't taken the car for a drive yet to see if I get passing gear, and to see what kind of shift points I now have. Maybe having that lever just short of fully forward will make little to no difference.

 

[70bigblockdodge]

If it won't stretch far enough you can put a bolt in the slot so it will push fully rearward at wot, which is what it should do, to maintain enough line pressure and not slip, this will make the demand for the downshift. However before 1972 there was no part throttle downshift you have to be at least 3/4 the way to the floor.

 

[Scotty]

If it won't stretch far enough you can put a bolt in the slot so it will push fully rearward at wot, which is what it should do, to maintain enough line pressure and not slip, this will make the demand for the downshift. However before 1972 there was no part throttle downshift you have to be at least 3/4 the way to the floor.

Cool, thanks! That is a good idea. I was thinking about using the welder to fill in the back side of that slot, then grinding and cleaning it up to look like original.

 

[Yatzee]

Under no circumstances leave the shift lever without movement. It's actually not a downshift lever, it's regulating
pressure to the servos for band tension and actuating shifting via pressure. If you want a simple, foolproof way
to correct this situation, use a shifter cable like the one Bouchillon Performance sells. It not only works perfect,
it also looks neat and tidy under the hood as compared to all the bell-crank crap.

 

[moper]

The factory adjustment is to have the lever on the trans be all the way back when the carb is at wide open throttle. The position when at idle is much less important but some (me included) find that it's best to shorten the slot. The issue is the length of travel of the 4bbl arm vs the 2bbl arm at the carb. So it might not ever be "perfect" without some non-standard work. But - if it's all the way back at WOT - that's the right spot for it.

 

[has2bmopar]

If this is a later AFB sold aftermarket to fit varied makes like a Competition Series AFB or an Edelbrock, they made an adapter that bolts to the existing throttle bracket on the carb.

You should match your length of throw on the carb to the kickdown lever. Blocking/shortening your slot in your linkage may not be a complete fix. The lever on the trans needs to be able to come fully forward when your throttle is closed.

Measure your length of throw on the carb and the transmission linkage individually. Either you could move the pin further from your fulcrum on the carb bracket, or look for a kickdown lever on the transmission that is slightly shorter.

 

[68Bigred]

Don't know if yours is like mine but when I put new carb on I had to move my linkage forward a bit and move the adjustment on tje rod going down out to get a good kickdown. Is it possible you didn't notice this adjustment? I actully did the bolt trick until I noticed adjustment here.

 

[Scotty]

Don't know if yours is like mine but when I put new carb on I had to move my linkage forward a bit and move the adjustment on tje rod going down out to get a good kickdown. Is it possible you didn't notice this adjustment? I actully did the bolt trick until I noticed adjustment here.

Yup, I adjusted that one too...
Tomorrow I will take the car for a drive after the last adjustments I made, if it doesn't get the passing gear I will lengthen the rods to get the full motion of the trans lever.

 

[66SportFury]

Not sure how you made out, but this might help. We did this video in May of this year. https://www.youtube.com/watch?v=avgCFdGKjtw

 

[Scotty]

Not sure how you made out, but this might help. We did this video in May of this year. https://www.youtube.com/watch?v=avgCFdGKjtw

Thank you, great info there! I still haven't had the chance to drive the car, but if it doesn't have passing gear after the last linkage adjustment I will try this pressure adjustment.

 

[66SportFury]

No, don't do the pressure adjustment before you have passing gear. If you don't have passing gear, don't drive it. You'll end up hurting the trans in the long run. You need to get that sorted out before you do anything else. Watch the video from 1:35. That's what you're looking for.

 

[Scotty]

No, don't do the pressure adjustment before you have passing gear. If you don't have passing gear, don't drive it. You'll end up hurting the trans in the long run. You need to get that sorted out before you do anything else. Watch the video from 1:35. That's what you're looking for.

Just drove the car and it now has passing gear!! :wtg:

 

[66SportFury]

Nice..!!

 

[mrzods13]

Having the same problem shifts properly but doesn't kickdown. I have the 2 bbl linkage but I extended the linkage with the part from edelbrock. Maybe I have something not right. I have it where the lever goes all the way back at wot. It doesn't slip or anything. I do have one of those performer rpm intakes so I had to get the high rise brackets for it.

 

[Scotty]

Having the same problem shifts properly but doesn't kickdown. I have the 2 bbl linkage but I extended the linkage with the part from edelbrock. Maybe I have something not right. I have it where the lever goes all the way back at wot. It doesn't slip or anything. I do have one of those performer rpm intakes so I had to get the high rise brackets for it.

Maybe when the go pedal is mashed to the floor the throttle cable isn't pulling the carb throttle linkage all the way back to WOT?

 

[mrzods13]

I might have to get the longer throttle cable.

 

[Scotty]

I might have to get the longer throttle cable.

I used one of the off the shelf, universal aftermarket cables. It works good

 

[Yatzee]

My recommendation is to toss the entire bell crank B.S. and go with a Bouchillon Performance cable shift system. It
looks so clean and there's no guess work to functionality. Installation is a breeze. Gotta love modern technology!