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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: gold84gmc on July 24, 2011, 11:48:23 am

Title: swapping 267/th350 to 350/th400
Post by: gold84gmc on July 24, 2011, 11:48:23 am
my dads truck (77 gmc stepside 2wd) had a 267 with a th350, were building a 350 to put in it, and we have a th400 that we wanna put in it, can we just put the th400 in with no mods or do we have to change the cross member and/or driveshaft, it has a one piece drive shaft
Title: Re: swapping 267/th350 to 350/th400
Post by: VileZambonie on July 24, 2011, 11:54:42 am
That all depends on the tailshaft length. Too many variables so just measure it.
Title: Re: swapping 267/th350 to 350/th400
Post by: gold84gmc on July 24, 2011, 12:08:39 pm
if they are different, can we swap the one from the th350 on to the th400?
Title: Re: swapping 267/th350 to 350/th400
Post by: zieg85 on July 24, 2011, 02:42:51 pm
Is the 4.3L and V-8 or V-6?
Title: Re: swapping 267/th350 to 350/th400
Post by: gold84gmc on July 24, 2011, 02:46:25 pm
what?
Title: Re: swapping 267/th350 to 350/th400
Post by: bigchevyc30 on July 24, 2011, 07:29:56 pm
hes asking is your motor a v-6 or a v-8
Title: Re: swapping 267/th350 to 350/th400
Post by: gold84gmc on July 24, 2011, 08:56:12 pm
267 v8
Title: Re: swapping 267/th350 to 350/th400
Post by: WilliamBos on July 24, 2011, 09:15:29 pm
Is the 4.3L and V-8 or V-6?

The 4.3 is 262.

Measure the trans, you may need a shorter drive shaft.
Title: Re: swapping 267/th350 to 350/th400
Post by: zieg85 on July 24, 2011, 09:38:31 pm
Is the 4.3L and V-8 or V-6?

The 4.3 is 262.

Measure the trans, you may need a shorter drive shaft.

Yes and the 267 is also considered a 4.3L.  I only asked the question because the frame mounts are different for the V-6...  Kick down is electric on a TH400
Title: Re: swapping 267/th350 to 350/th400
Post by: WilliamBos on July 24, 2011, 10:35:08 pm
Is the 4.3L and V-8 or V-6?

The 4.3 is 262.

Measure the trans, you may need a shorter drive shaft.

  Kick down is electric on a TH400


No TV cable like the TH350??
Title: Re: swapping 267/th350 to 350/th400
Post by: VileZambonie on July 25, 2011, 08:59:15 pm
The TH350 has a detent cable, the TH400 has a detent solenoid, the TH700R4 has a TV cable.
Title: Re: swapping 267/th350 to 350/th400
Post by: gold84gmc on July 26, 2011, 10:24:49 am
if it has a solenoid shouldnt it have a plug for a connector?, the th400 we have doesnt any connectors on it
Title: Re: swapping 267/th350 to 350/th400
Post by: bigchevyc30 on July 26, 2011, 08:10:56 pm
agreed i my truck has the th400 and i have only a vacuum hose going to it and the shifting linkage
Title: Re: swapping 267/th350 to 350/th400
Post by: VileZambonie on July 26, 2011, 09:52:23 pm
disagreed,

see image

(http://i6.photobucket.com/albums/y228/Sabaka454/400.jpg)
Title: Re: swapping 267/th350 to 350/th400
Post by: bigchevyc30 on July 26, 2011, 11:12:36 pm
so then whats the wire that hooks up for then and what would it do with out it hooked up cause i would like to know and on how i would wire it up. thanks for showing that vile i seem to learn something new about my truck every day
Title: Re: swapping 267/th350 to 350/th400
Post by: devanray on July 27, 2011, 05:17:54 pm
The wire going to Vile's pic would lead to the kickdown switch mounted behind the gas pedal, so when the pedal is dressed all the way than the switch will activate the kickdown in the tranny. The other wire from the kickdown will then go to a hot lead, can't remember if it is keyed or always hot.

First pic = kickdown switch
Second pic = where it the switch goes in the cab
Third pic= where the wire attaches on the 400 (bad pic, sorry)

I to have a 77 stepside now with a 350 and a 400, really can't stand the 3 gears though, you may plan on having to change your shift points and get a new speedo cable.

Good Luck