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junkyardpartseeker · 03-23-2003, 06:56 PM

I have a 84 suburban c-10 2wd. 350 motor and 700R4 Trans. I have edelbrock manifold 2101 and 1406 carb on it now. My trans is in need of rebuild. I have been told by trans shop that I have to put on stock manifold and q-jet carb and emissions again to run the lockup part of the trans. I am not sure what to do and am looking for anyone who can give me advice I would really appreciate it. Tommy

**swervin ervin** · 03-23-2003, 07:03 PM

Indeed, when you remove some of the emissions stuff, the lockup won't work. The wiring on the lockup is nothing but a big mess. I removed some of the stuff on mine, but my lockup didn't work before removing it. I could never figure out what was wrong, so I wired mine like in this article. Works great. BTW, the tranny shops don't know what they are talking about. I can see they've never had to make something work before.

Lockup

Oh, and welcome the forum.

junkyardpartseeker · 03-23-2003, 07:22 PM

Thanks Mike, The trans shop told me my lockup is vacuum and runs off a "x-mas tree" vacuum switch next to the thermostat housing. I don't want to loose my edelbrocks, they did well on towing trailers. I am stumped on what I need to do.

junkyardpartseeker · 03-23-2003, 08:31 PM

Another question I have is a friend told me I should think about changing over to the TH400 in this vehicle for towing. Any opinions would help.

79GMC454C35 · 03-23-2003, 09:57 PM

I switched a 700R4 for a turbo 400. Big mistake for my driving style. I was able to drive 85 & 95 with no problem with the 700R4. With the turbo 400 the RPM was very high at 70. The gas milage went way down because the RPM went up. Drive around in drive for a month instead of in overdrive to get a rough idea of the differences you will see.

**swervin ervin** · 03-23-2003, 11:40 PM

Tommy,

you don't really have to use the TVS, or Christmas tree, as you call it. I still have mine, because all the TVS does is control vacuum to things by coolant temp. You can hook vacuum straight up to the low vac switch without the TVS. I tried it this way and didn't like it because it would lock in 4th, like it supposed to, but it did it when cold and to me, seemed to lug the engine a little. The TVS won't let any vacuum go to the low vac switch until temps reach around 170 degrees or so. Here's a pic of my intake with the TVS mounted in it. It's a little hard to see, but if you look real close, you will see the black TVS right beside the thermostat housing.

Oh, and on the TH400 thing. They are tough trannys, but not needed for towing. Just make sure you tow in drive, and not OD. Also an external cooler is a must with 700R4's. Especially when towing.

03-23-2003, 06:56 PM	#1
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	Need info I have a 84 suburban c-10 2wd. 350 motor and 700R4 Trans. I have edelbrock manifold 2101 and 1406 carb on it now. My trans is in need of rebuild. I have been told by trans shop that I have to put on stock manifold and q-jet carb and emissions again to run the lockup part of the trans. I am not sure what to do and am looking for anyone who can give me advice I would really appreciate it. Tommy

03-23-2003, 07:03 PM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Indeed, when you remove some of the emissions stuff, the lockup won't work. The wiring on the lockup is nothing but a big mess. I removed some of the stuff on mine, but my lockup didn't work before removing it. I could never figure out what was wrong, so I wired mine like in this article. Works great. BTW, the tranny shops don't know what they are talking about. I can see they've never had to make something work before. Lockup Oh, and welcome the forum. __________________ Mike 1985 Chevy C-10

03-23-2003, 09:57 PM	#5
79GMC454C35 Registered User Join Date: Mar 2003 Location: Arizona Posts: 115	trans info I switched a 700R4 for a turbo 400. Big mistake for my driving style. I was able to drive 85 & 95 with no problem with the 700R4. With the turbo 400 the RPM was very high at 70. The gas milage went way down because the RPM went up. Drive around in drive for a month instead of in overdrive to get a rough idea of the differences you will see.

03-23-2003, 07:22 PM	#3
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	Thanks Mike, The trans shop told me my lockup is vacuum and runs off a "x-mas tree" vacuum switch next to the thermostat housing. I don't want to loose my edelbrocks, they did well on towing trailers. I am stumped on what I need to do.

03-23-2003, 08:31 PM	#4
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	Another question I have is a friend told me I should think about changing over to the TH400 in this vehicle for towing. Any opinions would help.

03-23-2003, 11:40 PM	#6
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Tommy, you don't really have to use the TVS, or Christmas tree, as you call it. I still have mine, because all the TVS does is control vacuum to things by coolant temp. You can hook vacuum straight up to the low vac switch without the TVS. I tried it this way and didn't like it because it would lock in 4th, like it supposed to, but it did it when cold and to me, seemed to lug the engine a little. The TVS won't let any vacuum go to the low vac switch until temps reach around 170 degrees or so. Here's a pic of my intake with the TVS mounted in it. It's a little hard to see, but if you look real close, you will see the black TVS right beside the thermostat housing. Oh, and on the TH400 thing. They are tough trannys, but not needed for towing. Just make sure you tow in drive, and not OD. Also an external cooler is a must with 700R4's. Especially when towing.



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