Backfiring while coasting & Transmission kickdown adjustment

[The_Handier_Man1]

From: Boise_Chief2  (Original Message)
Sent: 6/26/2005 2:29 PM

I have a couple of questions that should be easy.  While coasting down a hill my 413 backfires throught the muffler and I think I'm just a couple of degrees off on timing.  Does anyone know whether I'm alittle advanced or (he hee) retarded.

Also I upgraded to the 700 cfm Edelbrock carb and after changes to the kickdown and throttle cable it works good.  But I think my kickdown isn't st quite right.  What amount of throttle under heavy load should it take to get the tranny to kickdown.  Currently it takes 2 seconds at wide open throttle for the tranny to kick down.



From: HeavyHaulTrucker
Sent: 6/26/2005 11:50 PM

Chief, you own an old Winnie... is there any real doubt? 

Seriously, it could be off either way just a bit.  But you could just as easily have a little bit too rich or lean fuel mixture, too.

The way to adjust the kickdown linkage is to loosen the 7/16 bolt on the pivot; then push the transmission throttle rod back until you just begin to feel resistance -- the lever on the tranny will be at about a 90 degree angle to the tranny.  While holding the rod in that position, pull your carb's throttle plate to the full open position and hold it there.  Then use your third hand to tighten the hold down bolt! 

And yes, it really helps to have an assistant -- not many of us have three hands!

John



From: Slantsixness
Sent: 6/27/2005 11:25 AM

BoiseChief2,
Here's a little extra tidbit....
Be sure to have a return spring for the kickdown linkage.

usually you can undo the 7/16" bolt, floor the carb (make sure the chock is open and the secondary linkage is not bound. take your thumb and push the shift down rod as far as it will go... make sure this doesn't bind the floored carb linkage! Now hold the bracket in place and let the throttle return to idle. make sure it moves freely and folllows the throttle, without binding.

On rare occasions, the kickdown servo or lever return spring inside the trans can go bad.

Tom