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TV-rod: carburetor link length?

Started by pocale, December 11, 2017, 10:10:28 AM

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pocale

Hi,
The friend's '56 - w/ original hydramatic - has aftermarket Edelbrock AFB carb. Trans TV-rod now fitted to a diy carb lever adapter, but as the movement of the lever is stupid design i am pretty sure the lever length is not right either.
The shift feel is not as good as it should and missing kick-down.

Before taking time to adjust the rod, it would be good to know what is the factory length of the carb TV-lever, measured from the throttle shaft to the TV-rod axle center?

thanks.

edit: typos
V8, A/T, RWD - other options are negotiable

savemy67

Hello Juho,

My reprint of the '56 shop manual includes 94 pages on the Hydra-Matic (section 12).  I can find no specification for the dimension you request.  However, on page 12-58, the T.V. Rod linkage adjustment procedure is given with reference to figure 12-54 (located on page 12-58).  There is also figure 12-53 (located on page 12-57) which shows all the linkages.

The T.V. rod had a clevis at the transmission end, and a trunnion at the carb lever end.  Does your friend's '56 still have the trunnion at the carb lever end?  If so, you can adjust the T.V. Rod and hopefully restore proper functioning of the valve.

Does your friend's '56 still have the original relay lever and relay bracket?  The relay lever transmits the accelerator pedal movement to the carb throttle shaft (carb lever).  There is a hole in the relay lever and bracket that should be aligned with a 1/4 inch drill bit after disconnecting the relay lever to carb lever rod at the relay lever end.  The purpose of the drill bit is to make sure the relay lever to carb lever rod is adjusted properly with the carb at idle.  This adjustment needs to be done first.  Don't forget to reconnect the rod.

The T.V. Rod can then be adjusted by loosening and or disconnecting the carb lever end of the T.V. Rod, and pushing the rod to the rear of the car until the T.V. lever on the side of the transmission reaches its stop.  Then the carb lever end of the T.V. Rod can be connected to the carb lever.

Your post mentions that the carb is equipped with a DIY carb lever.  If there is no provision for adjusting the T.V. Rod by means of a threaded connection, you can probably bend the T.V. Rod until it aligns properly with the carb lever.

If you have some pictures, please post them.  There may be something that others will see that might further assist you.

Respectfully submitted,
Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

Caddy Wizard

Have had 2 1956 models and have installed a fuel injection system on a 49.  So I am familiar with your issue.

First of all, on the carb, locate a place on the throttle linkage that is the same radius (same distance from the center of the throttle shaft) as on the original carb.  You also want it to be "clocked" at the same orientation relative to the throttle shaft.  That is where you want the TV rod to tie into the Edelbrock throttle linkage.  Essentially, you want the TV rod to tie into the Edelbrock in the same way that it does with the stock Carter or Rochester.  By doing so, you will get the same movement of the TV rod at the transmission in relation to movement of the throttle as you would have with the stock carburetor.   This is important.  On the fuel injected 49, I had to make a little adapter that I added to the throttle linkage to get that stock geometry.  Here is a picture of how I did that.

Then you should be able to follow the procedure in the manual.  As I recall, it involves "seating" the TV rod in the closed position and backing it off so many turns from there.  Anyway, the procedure in the shop manual will work if you can mimic the attachment at the carb as I outlined above.
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

pocale

With longer lever and designed lever geometry the shift feel is now much smoother.
thanks.
V8, A/T, RWD - other options are negotiable