Hi chaps wondering if anyone can help. Have a 347 57 Pontiac chieftain with edelbrock 1405 performer 600 and performance cam. Recently the transmission has been causing me issues. Symptom kick down coming in at around 55mph and not changing back up, anything up to this speed working as normal, takes off like a scalded cat and changes up at around 20mph. Floored her the other day just to see what would happen as used to get to around 130 with no issue, but this time she reached 90mph ran out of steam and began popping and banging. I think the problem is in the transmission and something to do with the kick down mechanism, but a very grey area and cannot find anything on the interweb to help. View attachment 4559570
Sounds like a kickdown adjustment problem. For speeds over 55, you need more throttle for the higher power required, which is causing the trans to think you have more throttle than actual. So it kicks down out of high and will not shift back up. The carb and intake change is the likely source of the problem. You need to duplicate the linkage adjustment of the original carb and intake.
Since mine is a stick shift with tripower I really haven't got an answer to your problem/ The one thing I will tell you is I would never go that fast in my '57 simply because the stock brakes were never very good even when new! You are a much braver man than me! KK
Yes buddy, hits 120 with ease. I know it’s surprised a lot of people to how quick she is. Sent from my iPhone using The H.A.M.B. mobile app
I’m in the UK, couple of mates have tried to out run me on the motorway and surprised I stick up their ****, and have have had a few shocked people when I’ve run her on the sand. Sent from my iPhone using The H.A.M.B. mobile app
She been running fine on this set up for two years but problem has just started. I was suspecting the kick down linkage. I’ll strip it down and see how it goes. Sent from my iPhone using The H.A.M.B. mobile app
Hahaha I’ve found the brakes pull her up fine, have fitted the heavy duty drum set. Sent from my iPhone using The H.A.M.B. mobile app
From what I read in the service manual, with D4 selected even with the throttle held fully down with the kickdown valve opened it'll eventually change up to 4th at about 70MPH. Full service manual: http://www.oldcarmanualproject.com/manuals/trans/GMControlledCouplingTrans/ If it's doing everything else as prescribed, it sounds like it's getting hung up in D3 (or the selector mechanism has become loose and D4 is actually now the position on the indent for D3) and it'll stop changing into 4th then. Particularly if it gives you gears 1, 2 and 3 correctly. If not then the valve body's become clogged up or otherwise impaired and could probably do with cleaning out and/or service. --Phil
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