![]() |
![]() |
#1 |
Registered User
Join Date: Jun 2011
Location: Valencia, CA
Posts: 18
|
Whazziss?
I recently purchased a 1972 GMC 2500 Sierra from the original owner. It's got the 402 cu. in. engine with 400 turbo transmission, and it's in pretty great shape.
Here's my question: Under the dash, behind the heater hose, there's a button that pushes up. The former owner told me it does something to add oomph to the throttle and that it came stock with the truck. I later looked through the manual, did Google searches and even talked to a couple of mechanics, and I'm not able to find anything on that gizmo. Does this sound familiar to anyone? Thanks ahead of time. ![]() Last edited by capturedlive; 06-21-2011 at 07:43 PM. |
![]() |
![]() |
![]() |
#2 |
Registered User
Join Date: Jun 2011
Location: Valencia, CA
Posts: 18
|
Re: Whazziss?
My new toy:
![]() |
![]() |
![]() |
![]() |
#3 |
Registered User
Join Date: Jan 2011
Location: Townsend MT
Posts: 1,725
|
Re: Whazziss?
Does it have A/C? I think it is the switch to turn the A/C compressor on. I don't exactly know what your talking about. A picture would help a lot.
![]()
__________________
1966 F250 4X4 416 1972 K20 350 4 OTF Last edited by 1972RedNeck; 06-21-2011 at 08:04 PM. |
![]() |
![]() |
![]() |
#4 |
My Carbon Footprint
Join Date: Oct 2008
Location: Orygun
Posts: 5,527
|
Re: Whazziss?
Well first of all welcome. Second is your a show off (Awesome looking truck lol). Lastly are you talking about the vent hoses? Can it be said turbo 400 kickdown? Can't remember what they look like or where they are located on these trucks even though I've had a couple with the th400.
Posted via a killer Mobile Device Last edited by prostreetC-10; 06-21-2011 at 10:20 PM. |
![]() |
![]() |
![]() |
#5 |
Roadtrip!
![]() Join Date: Feb 2003
Location: Grand Rapids MN
Posts: 13,737
|
Re: Whazziss?
If you are looking at the switch above the gas pedal, that is the kickdown for a turbo 400. I think if you push the gas pedal down while you are looking at it it should make contact. 71-72 had this setup i believe.
Nice truck!
__________________
67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto |
![]() |
![]() |
![]() |
#6 |
Moderator
![]() Join Date: May 2007
Location: Southern Cal
Posts: 20,006
|
Re: Whazziss?
You are describing a kick down switch....yet the location you are describing is the A/C compressor switch. Kickdown switch should be on the gas pedal on a 71-72 truck.
__________________
1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man |
![]() |
![]() |
![]() |
#7 |
Registered User
Join Date: Jun 2011
Location: Valencia, CA
Posts: 18
|
Re: Whazziss?
Thank you all for the replies.
Well, I just looked at some kickdown switch pics on Google Images and, sure enough, that's what it is. I just gave a poor description of it, the vent hose partially obscures it and it feels like it's off to the right of the gas pedal a little. I do have A/C, but I don't recall him telling me to hit any buttons to get that going. It just gets cool whenever I turn it on. Sorry I didn't provide a pic myself, but it's hard for me to get down in there and get a decent shot. I guess my next question would be, how do I use it? Do I engage it when the truck is moving, or do I have to push it when it's stationary? Does it disengage on its own when it reaches a certain speed? I just don't want to do something stupid and hurt the truck. |
![]() |
![]() |
![]() |
#8 |
Roadtrip!
![]() Join Date: Feb 2003
Location: Grand Rapids MN
Posts: 13,737
|
Re: Whazziss?
You shouldn't have to do anything except drive it. When you go to WOT (wide open throttle) it should down shift automatically (providing it is all hooked up and working)
__________________
67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto |
![]() |
![]() |
![]() |
#9 |
Registered User
![]() Join Date: Apr 2011
Location: brooks,georgia
Posts: 674
|
Re: Whazziss?
|
![]() |
![]() |
![]() |
#10 |
Born Psycho
![]() Join Date: Feb 2001
Location: brentwood,cal,usa
Posts: 4,884
|
![]()
thats exactly what it is-kickdown switch. welcome from nor cal
__________________
jerry moss 72 cheyenne super K20- tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,tow hooks,bumper guards,toolbox,aux. fuel tank,posi front and rear,plus other goodies!!! SOLD 69 suburban K20-tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,4 inch all spring lift,4 speed, 14 bolt full floater, dana 44 HD,warn winch,posi front and rear,tow hooks,plus other goodies. 73/80 chevy/gmc K20 SB400,turbo 400,205,tilt,a-c,gas hog. 77 K/5 cheyenne blazer-daily driver/beater. SON HAS IT NOW BRENTWOOD,CALIFORNIA |
![]() |
![]() |
![]() |
#11 |
Senior Member
![]() Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,921
|
Re: Whazziss?
That is your passing gear. The THM 350 had a mechanical kickdown cable and the 400 was electrically operated. They do the same thing.
|
![]() |
![]() |
![]() |
#12 |
My Carbon Footprint
Join Date: Oct 2008
Location: Orygun
Posts: 5,527
|
Re: Whazziss?
correct
|
![]() |
![]() |
![]() |
#13 |
Old Skool Club
![]() Join Date: Jun 2001
Location: Benton, AR "The Heart of Arkansas"
Posts: 10,880
|
Re: Whazziss?
Earlier versions, like my '69, had the kick-down switch at the carburetor. When I got mine, the switch had been eliminated, due to a non-stock (AFB) carburetor installation. You'd think the P.O. would have been able to figure out how to mount it and also learn he still needed it, but then you wouldn't believe some of the other stuff that he did to it.....
__________________
Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was. |
![]() |
![]() |
![]() |
#14 |
Registered User
Join Date: Jun 2011
Location: Valencia, CA
Posts: 18
|
![]()
Thanks again for all the valuable input. I haven't taken the truck out on the freeway since I brought it home, but next time I do, I'll have a go with the kickdown switch and see if it turns into the Batmobile.
On a related note, a mechanic suggested that I might want to replace the 400 with a 700(R4?) because I wasn't planning on using the truck as a hauler. Personally, I'm usually in the camp of "If it ain't broke, don't fix it," but I'm always up for illumination from the masters. |
![]() |
![]() |
![]() |
#15 |
Back in the sticks
Join Date: Jan 2001
Location: Fordland, MO
Posts: 3,188
|
Re: Whazziss?
Good call on the "if it ain't broke, don't fix it". Drive it til the wheels fall off or the 400 gives up. The 400 used to be all there was for towing unless you had a manual transmission. I'm betting it will tow just about anything you want and do fine at it.
__________________
1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty |
![]() |
![]() |
![]() |
#16 | |
Roadtrip!
![]() Join Date: Feb 2003
Location: Grand Rapids MN
Posts: 13,737
|
Re: Whazziss?
Quote:
If the trans is working fine, i wouldn't change it..
__________________
67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto |
|
![]() |
![]() |
![]() |
#17 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,274
|
Re: Whazziss?
The Turbo 400 trans is one of the best transmissions ever made. They will stay behind a big block for years, no problem.
Now the suggestion you might want to switch to an OD tranny would be for fuel mileage purposes. 700R4 installs are all over these forums if you're interested. If mpg isn't a great concern of yours just drive it and enjoy it. ![]()
__________________
Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
![]() |
![]() |
![]() |
#18 | |
#16876
Join Date: Apr 2005
Location: Auburn WA
Posts: 12,266
|
Re: Whazziss?
Quote:
__________________
Posted via Stationary Device '71 Custom Deluxe C-20 402. '67 Buick Special 455. '49 Plymouth Special Deluxe. "I love that old car smell" ![]() Some people are like Slinkies... not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs. |
|
![]() |
![]() |
![]() |
#19 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
|
Re: Whazziss?
if you have the original 3.07 gears, you'll be fine on the freeway.
|
![]() |
![]() |
![]() |
#20 |
Roadtrip!
![]() Join Date: Feb 2003
Location: Grand Rapids MN
Posts: 13,737
|
Re: Whazziss?
3/4 ton with big block and auto... Wouldn't that have 3:54 or maybe 4:10 gears?
__________________
67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto |
![]() |
![]() |
![]() |
Bookmarks |
|
|