Author Topic: 78 Chevy C20 TH400 Kickdown  (Read 524 times)

Offline 78 Chevyrado

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78 Chevy C20 TH400 Kickdown
« on: August 09, 2026, 12:10:23 am »
I don;t know why it was like this but when I got the 78 C20 it would never kickdown ever...

I tried to set it by the way the manuals say to do it.

Still didn't work.  So I did this mod to my switch under the dash.   The way to set it is to pull it one way then floor the gas and it will set that switch.  well on mine if you floored the gas it never even touched the switch.  no idea if that was from factory or grandad did something wrong but here was my solution.  wrap ever larger pieces of hose until it acts right.  took this much of layers of rubber hoses to make my truck act right.  It's been perfect ever since, 20 years and growing.

Kenny

1978 C-20, 350/400, 3.73, Graystone Metallic, Raceline Renegade 8 Wheels - 18x8.5, 275/70R18 BFG KO's

Offline JohnnyPopper

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Re: 78 Chevy C20 TH400 Kickdown
« Reply #1 on: Today at 12:57:18 pm »
Clever!

So it's electric? I thought that year range was still a mechanical cable.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline zieg85

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Re: 78 Chevy C20 TH400 Kickdown
« Reply #2 on: Today at 01:05:57 pm »
all TH400's where electrical kickdown.  Location of the switch on the CK's is on the go pedal. 
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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