6.2 transmission kickdown

[dolmstead2007]

I know the CUCV's came with a TH400 and they have a vacuum kick down from what ive read. Can you put a Th350 behind one? I wanna put a surplus 6.2 in a truck that has a TH350 and np203 how would i run the kick down on the TH350?. I asked my local trans shop and they looked at me like i was stupid when i was talkin about a vacuum kickdown on the 400. Im new to these gm engines but not new to bein a grease monkey any help is appreciated Thanks Dave

 

[nk14zp]

The kick down on the cucv was electric .

 

[nk14zp]

And welcome to the site.

 

[acmunro]

Not sure about the TH350. Would it work with the 6.2/700r4 flywheel ? Anyone ? The kickdown would probably work with factory parts from a 6.2/700r4 - the T.V. cable bracket/linkage. One good thing about the TH350 is it will work just fine without the kickdown, if you don't mind bumping the selector down into second when needed. The 700r4 doesn't last very long without the T.V. Cable connected and adjusted properly.

 

[Wile E. Coyote]

The kick down on the cucv was electric .

I've never seen an electric one on a CUCV. I have a bunch of M1008s and M1009s here from 84-87 and they all have the VRV (Vacuum Regulator Valve) setup which takes vacuum generated by the vacuum pump (mounted in the 'distributor' hole at the back of the engine) - regulates it according to the throttle position at the injector pump - then sends it down to the accumulator mounted on the transmission.

The VRV is the black thing mounted to the side of your injector pump, with hoses running to the hard vacuum lines just below it. One vacuum side goes to the vacuum pump at the back of the engine -- the other goes to the transmission accumulator. Those hoses rot something fierce and the VRV bodies develop leaks over time which causes all manner of shift point problems.

Basically the vacuum pump/VRV setup mimics what you'd normally find on an older gas engine setup where the vacuum is also used to shift the transmission, so if you have a THM350 lying around you should be able to just hook right up to the accumulator with the existing CUCV plumbing (though the accumulator position is physically different on the THM350 vs the THM400.) Several trucks were spec'd for various agencies with the 6.2/THM350 setup right from the factory including one of the USAF crew vans I have here and another ex-BLM pickup.

(Later model year 6.2s and 6.5s - at least according to the civvy manual here - had an electronic Throttle Position Sensor (TPS) vs. the VRV, but again - I've never seen that on a CUCV.)

 

[dolmstead2007]

I want this to perform as well as possible as its mostly gonna be a wheeling play truck that i can drive on the streets a little too. i was also told the snout clearance on the starters is longer on the 6.2 diesel than the gassers. I guess if i had to do a tv cable that wouldnt be a big deal just never had good luck setting them before either that or a run a manual/ auto valve body. And gotta say great site lots of info

 

[dolmstead2007]

OK well being as the engine doesent have a ip and was gonna get one form a civilian truck along with a 12v starter, because the truck is 12v and I dont mess with resistors and stuff do you guys think there would be a vrv on the civilian pumps or is this a military only option? As for me running a kickdown i really doubt it can be much harder than tryin to make control cables and rig an airplane. If i do this ill probly go with a lokar cable or something similar. Am i looking at getting myself into a big headache if so ill just not mess with it? Again any help is more than what i have Thanks Dave

 

[G-ray]

Hello. New here hope I can help. The TH400 has a vacuum modulator and an electric kickdown solenoid, The switch is on the accelerator bracket under the dash. The TH350 has a vacuum modulator and a cable kickdown. The TH700R4 has a TV cable and no vacuum modulator. All three use the same flexplate. There are two different torque converter bolt circlesand if I remember right deisels have six torque converter bolts and the rest have three. as long as three of the holes in the fexplate line up with the holes in the torque converter it will work. If you want to use a TH350 just hook the vacuum line to the valve on the IP just like the TH400 and hook the kickdown cable to the stud on the throttle linkage on the side of the IP. You will need a throttle cable bracket with the hole for the kickdown cable, the bracket for a TH700R4 will work.

 

[acmunro]

I thought the 700r4 and TH400 flexplates were different.

 

[nk14zp]

Hello. New here hope I can help. The TH400 has a vacuum modulator and an electric kickdown solenoid, The switch is on the accelerator bracket under the dash. The TH350 has a vacuum modulator and a cable kickdown. The TH700R4 has a TV cable and no vacuum modulator. All three use the same flexplate. There are two different torque converter bolt circlesand if I remember right deisels have six torque converter bolts and the rest have three. as long as three of the holes in the fexplate line up with the holes in the torque converter it will work. If you want to use a TH350 just hook the vacuum line to the valve on the IP just like the TH400 and hook the kickdown cable to the stud on the throttle linkage on the side of the IP. You will need a throttle cable bracket with the hole for the kickdown cable, the bracket for a TH700R4 will work.

You are right thanks

 

[G-ray]

I did a little research and this is what I found. The 700 uses the small 10.7" bolt circle with 6 bolts. The 400 uses the large 11.5" bolt circle with either 3 or 6 bolts. Not sure about the factory flexplates but replacements have both sets of holes. 350s and 400s can use the same torque converter. I don't think 6.2s ever came with 350s so You would need to use a low stall diesel converter from a 400.

 

[dolmstead2007]

Well Thanks everyone seems to be alot of knowledge and help here with this. So i figured out the vacuum part now. That it goes from the injection pump to the modulator . And as the kickdown goes ill just run a linkage form the stud on the injection pump to the kickdown on the trans right? Is there any difference between the military and the civilian injection pumps besides the 12v and 24v systems it takes to operate them? Im plannin on running a civilian IP bc the engine im buying is missing a pump. I wanna make sure the civilian still uses the vacuum controler on the pump. You guys are alot of help. Thanks Dave

 

[dolmstead2007]

If someone has a spare starter could they measure how long it is from the bolt holes to the snout of the starter the part that goes insid e the bellhousing. Ive read that the gassers have a shorter snout than the diesels and a diesel wont fit in a gasser transmission. Thanks Dave