Newbie with a Burb

[85K2500]

Hey everyone, I've been lurking for a while now, in fact... ever since I bought my old rusted out 85 GMC K2500 4 speed.

Now that it has been sold, I'm on to a new project.... An 85 GMC Burb Sierra Classic C2500 3/4 ton with a seized 6.2 and a TH-400 auto that I really need to change out for a biefed up 700R4. The seized 6.2 is a J code, and it has some equipment I haven't seen before. A large electronic modual with vacuum hoses comming out of it right where the sorry excuse for a PVC replacement would be (large copper colored diaphram lookin thing), a large silver canister in the intake path (pre-cleaner), and according to the glove box label, California Emissions????? No idea what that entails... I found a good running, low mileage 6.2 C Code out of an 83 Van for sale, and I want to swap that in if I can.

So, I have a few questions out of all this mess.

1. What do I need to swap off this J code onto the C Code to make it work right, cause IIRC the California trucks had a PCM of sorts....

2. What all is entailed in the CA Emissions package?

3. Is this some kind of rare color on this truck, Code 64 Desert Sand Metallic?

Pictures will be up tomorrow...

Thanks in advance!!

[DmaxMaverick]

Welcome aboard!

A couple things.......

The J code engine and fueling is much desired over C. Especially if it has CA emissions. The ONLY difference between them is EGR (Exhaust Gas Recycle), and TCC (Torque Converter Control is different for CA emissions, with a TH700R4, no TCC with a TH400, as it has no lockup converter). CA emissions does not have a PCM, but an ECM (Emissions Control Module, not Engine CM). No electronic control of engine operation, other than monitoring of EGR. If you have a J code, stick with it. You'll have a higher potential for power and/or economy. CARB has yet to actually improve anything. And, the C code engine will have more stuff to fix, and go wrong. Most often, C code's are converted to J's.

The PCV thing you mention is the CDR (Crankcase Depression Regulator). Essentially, a PCV for Diesel engines. A very necessary item, as it prevents dirt from being sucked passed oil seals at higher RPM's. No real maintenance involved. They work, or they don't. You can clean it, but that's it.

Not sure what you mean about the large electronic module with the vacuum hoses. Probably the cruise control module. If it has an actuator connected to the throttle, that's what it is.

The large silver canister in the intake plumbing is the baffle/pre-cleaner. Not only does it eject dust, bugs, etc, it will lessen the intake noise, which can be quite loud under certain throttle and power levels. Just the nature of N/A Diesel engines.

Converting from a TH400 to a TH700R4 is not a bad idea, IMO. As long as it's built right. You will have some other mods to do, other than just the tranny swap. You will need to install a TV cable (Throttle Valve cable), and the wiring for TCC. You may also want to swap the IPC (Instrument Panel Cluster), with the 4 gear selection places (1/2 ton auto IPC of similar year). The better 700 cases are the '87 and later with a large "K" on the case. I recommend this case, especially with your heavy rig. Most times, it's better to source you own core, and build it yourself, or have it built with the right upgraded internals at a competent shop. Robyn, and others, can likely give you the best advice on this (the last one I did was nearly 15 years ago).

[6.5 Detroit Diesel]

Welcome! Good luck with the swap. You'll find all you need to know here. :D

[Robyn]

The engine stuff as Maverick mentioned is very basic and real straight forward to take care of.

The Module up front IS the cruise control and it will work fine on the new engine (if it is in working order)

The 700R although not my favorite tranny can be built to do a good job but it will cost some $$$ to do it right.

The TV cable Maverick mentioned is of the utmost importance and the linkage and brackets to mount it all an absolute "MUST HAVE" to make it work right.

Thism cable and assembly controls the internal pressures of the tranny as they apply to the operation of the bands. clutches etc.

An improperly adjusted TV cable can ruin a tranny in a few minutes.

When properly adjusted the tranny should shift out of 1 at around 15 MPH with very light throttle and then with the throttle to the mat the tranny should drop right back to 1 again.

As far as the controls for the lockup goes, transgo makes a stand alone hydraulic setup to run the lockup without any electrical hookups.

These work great. You do need to have a valve body that has the valves installed for the TCC.

The later 700R's have the TCC all controled via the ECM.

87-88 K case units should have what you need. If not you can swap in a VB from one that does.

I have built 700's using this stuff and its sweet.

To get a 700 to work well and live is tricky.

The following is a great start on an upgrade

13 vane front pump
HD front sprag
HD planet carriers
Beast sunshell upgrade
HD aftermarket input clutch drum with support ring installed on spline hub area.
All clutches upgraded to more frictions and better steels.
HD rear sprag
New thrust washers

This is just a few important parts I can think of.

Transgo has a publication out on all the tweeky trick stuff that needs to be done to make a 700R live.

Also a HD transgo shift kit 2-3 is the ticket too.

Set all the adjustments (Mods) on KILL and the little creature will live.

The 700 has one big issue, Its small as far as the size of its components.

Too complex and the TV system really sucked.

Once all the issues are addressed things are sweet.

The box is still small compared to a 400 or a 4L80 though.

The clutch drum is aluminum with the input shaft pressed into the drum

The early 700's would snap the input shaft and that was game over.


Best

Robyn

[85K2500]

Thanks for the welcome and all the info!! My first priority is getting the new engine in so I can drive her! Trans upgrade is probably a year or so down the road. I want to try to get her back to her original color too. Gonna try pressure washing the Macco Special Paint job off.

OK, here are the pics. http://s627.photobucket.com/albums/tt354/xp29h72/Suburban/?albumview=grid

[NutNbutGMC]

Thanks for the welcome and all the info!! My first priority is getting the new engine in so I can drive her! Trans upgrade is probably a year or so down the road. I want to try to get her back to her original color too. Gonna try pressure washing the Macco Special Paint job off.

OK, here are the pics. http://s627.photobucket.com/albums/tt354/xp29h72/Suburban/?albumview=grid
Nice looking machine. Welcome aboard.

If you don't find it here, it doesn't need to be found.