View Full Version : 350 TBI in Chero
04-11-2003, 12:47 AM
I am starting to gather parts for another project I have in the works. I want to use my TBI 350 I pulled out of my 88 Suburban. I have pulled the computor and traced the wires to where they went and cut them. So I have the harness, some plastic boxes that were under the dash no idea what they are or do. I also pulled the speed sensor plug from the Speedo. After thinking about it I am not sure the computor and wiring will work, as it is for the 350 TBI and 700 R4. I know we have some members well versed with GM, much more than I anyhow. With what I have indicated above, here is what I want to do and need to know.
Put the TBI 350 into a 80 Chero, TH400 behind it. What do I need to make that happen? Will the computor I pulled from the Suburban work, even though it is for the 700 R4? What What I assumed is the Speed Sensor, what can I do about that since the Chero Speedo has no provisions for the speed sensor? What else am I missing? All info on this...........GREATLY Apreciated! ;)
04-11-2003, 12:55 AM
Gees!!! :rolleyes: I took to long to type this post, and now The Anti-Chrysler Has left the Forum!!!!! :( It realy sucks to be a slow typer!!! :eek: Now I have to Wait!!! ;)
[ April 11, 2003, 06:56 AM: Message edited by: Crazy_Jeepman ]
04-11-2003, 01:31 AM
Gees!!! I took to long to type this post, and now The Anti-Chrysler Has left the Forum!!!!! It realy sucks to be a slow typer!!! Now I have to Wait!!!
Ha ha, no, I'm here!! I just have to make it look like I'm working every now and then, so I have to duck out sometimes.
Let's see what I can clarify.
1. The ECM on your generation computer has basically nothing to do with the transmission, with the exception of the 4-plug connector at the transmission (not all 4 terminals are used) for the lockup torque converter. Any pre-1993 vehicle does not have an electric transmission. You could leave that terminal disconnected, and it would not effect the performance of the engine. The prom (chip) in the ECM is programmed for your 350. That ECM is 99% for the engine.
2. The 700r-4 tranny of that vintage is controlled by a throttle valve cable (NOT a kick-down cable). Shifting points and fluid pressure are based on throttle angle. Again, this is via cable and not the ECM.
3. Painless wiring makes an in-line vehicle speed sensor, vss, which screws onto the threaded boss on the transfer case, and has threads on the other end to screw your speedo cable back on. You DO want this, for functions like idle speed control (the engine will go into fail safe mode without a vss) - it will not slow idle after you have driven without a vss. It takes 2 minutes to install - 2 wires and you're set.
4. Painless wiring also makes a stand-alone harness for the TBI engine. You can definitely use the one you have, but it may be messier. The new ones are a pretty penny.
5. I recall Advance Adapters has 350 engine mount conversions for the FSJ.
6. If you go TH-400, make sure you use a tranny from a 350 truck engine, and not from a 454. The 454 torque converter might have a different stall speed leading to less than available performance. If you use a late 80's TH-400, you may be able to retain the lockup torque converter, a very nice feature IMHO.
Anything else???? :D ;)
[ April 11, 2003, 07:40 AM: Message edited by: The Anti-Chrysler ]
04-11-2003, 01:42 AM
Thanks I am sure there will be. I did find some things that the 6 wires from the Computor to under the dash were hooked into, plastic Cigerette pack sized boxes. I will take some pics of what I have see if it is important or not. ;)
04-11-2003, 01:49 AM
If it's near the computer, it will probably be the vehicle speed sensor buffer. It contains the axle ratio and tire size information to give the correct speed information to the computer. The '88 may have it's speed sensor in the instrument cluster, if it still uses a conventional speedometer cable. The vss main lead pair will be wrapped together, one wire is green I think. They're the only wires loomed together.
The only things that should be connected to the engine harness, off the engine itself, are the:
1. Spark Module (black plastic square, with the engine production sticker on it, like "DDS" etc.
2. The ECM
3. The vehicle speed sensor and buffer.
4. Fuel pump relay.
I think that's it, if you can take a photo I should be able to identify what you're looking at.
04-11-2003, 02:08 AM
CJ, this is also the same conversion that Brent at BJ's Off-Road has in his Cherokee.....shoot him a message at firstname.lastname@example.org
04-11-2003, 03:22 AM
Thanks billyrb TH-400, with the lockup torque converter would be nice, I will look for one. Can an older TH400 be converted to lockup torque converter?
04-11-2003, 03:31 AM
No. There's a different torque converter, a special solenoid to allow the fluid pressure to build up so that the converter clutch plates will press together, and the plug on the tranny casing.
It is possible to use a converter-clutch equipped transmission on a carburated vehicle with a stand-alone system, if that's what you're thinking of.
I think your lockup TH-400 would come from a 3/4 ton 4X4 from '87 to '92. '93 saw the 4L-80E electric tranny. Lockup TC's are almost like having O/D when you get rid of all the slippage.
04-11-2003, 03:53 AM
the 64/65 caddy's used a 2 speed converter that you can hook to a switch on the dash and change the stall with a flick (1900 rpm and 2400rpm) i ran one in a cj-5 the cores can be had cheap all you need is the front pump/valve body and a rebuilt twin pitch converter can be had for $65.00 as for the lock up th400 they were know as the 4L80E
04-11-2003, 04:25 AM
The 4L-80E is actually a hybrid of the 700r-4 and the TH-400. It's a 4 speed O/D transmission, which replaced the TH-400 in 1993. It has the O/D of the 700r-4 (later the 4l-60), with the strength of the TH-400.
I think attempting to use that Caddy tranny would open up a whole other can of worms, although the fact they had the concept at that time is intriguing.
04-11-2003, 04:40 AM
the 4L60E is the 700r4 the 4L80E is a elec version of the th 400 the caddy twin pitch set up is a piece of cake to do b&m sold millions of the set ups and they can still be found at speed shops and if you are going to rebuild you could also go with the hd sprag a underdrive or overdrive planetarey and the twin pitch and also make the valve body full manual which would give 6 choices of foward gears and 2 reverses plus low gear combo's you could also run a 208/205/241/rockwell
04-11-2003, 06:16 AM
I guess it all depends on what C_J wants to do. I am not familiar with the Caddy setup.
Technically, the 4L60E is not the 700R-4. It is a fully electronic, upgraded version of it. Most of the internals are different. Gear ratios are always the same.
The progression of the tranny was this:
1982-1989 - TH-700r-4 (heavily upgraded around 1988)
1990-1992 - renamed the 4L60, better shift servos
1993+ - 4L60E fully electronic controlled
The TH-400 was never a 4 speed transmission, and was never electronic. It went one shot to a 4 speed and fully electronic as well in 1993. It saw one of it's first debut's in the 1993 454SS pickup. The first through third gear ratios are the same as the TH-400, and not of the 700r-4, and it has the same durability of the TH-400, giving it status from the factory behind big blocks. It is also used now behind the 6.0 liter V-8.
04-11-2003, 09:08 AM
Oh I want to Keep it simple. The plain Jane TH400 will be just fine. I have tons of parts for them and even kinda understand them. I thought if it was just a matter of swapping a Torque Converter to get an electric lock up. I would be up for that. Not interested in modifying or going to an OD trans, that is someone elses game not mine, I tried it and lost twice! :(
04-11-2003, 01:19 PM
Maybe someone can answer this I have a 94 suburban TBI 350 / 4l60e is the tranny stand alone can I remove the TBI and ignition and replace with carb and new distributor or will the tranny freak out on me....thanks
04-11-2003, 04:16 PM
do you have a cable going to the trans from the tbi ?????? if so stand alone
04-12-2003, 11:46 PM
No cable...I was wondering what it needs to operate, a throttle position sensor? , or is it from the ignition?
04-14-2003, 12:33 AM
Forget about it. You may be able to get a stand alone harness for the tranny aftermarket, but you can't use the original. The PCM is combined for the engine and transmission, and it controls the tranny via several sensors and various inputs. It also uses the shift sensor around the shift input, for functions like the 2nd gear start. If you were to go that route, I would either swap in the whole engine / tranny combo, or get a pre 1993 tranny.
04-14-2003, 01:19 AM
I most likely will get the Painless wiring, but in case using this wiring is possible, and can be explained what I need and don't need. That would be cool :cool:
04-14-2003, 02:39 AM
That larger black box looks like the cruise control module.
That blue box is the DRAC digital ratio adaptor controller. It's the predecessor to the VSSB vehicle speed sensor buffer. The other ends of those leads would go to the speed sensor in the instrument cluster. The blue box contains the factory axle ratio and tire size on your old Sub. Superlift makes conversion units.
The single yellow wire and plug from the DRAC should go to the cruise control mudule. It's the cruise signal wire.
The plug you label "computer plug" looks like the fuel pump relay plug.
The "empty plug under dash" you have labeled looks like the instrument cluster connector, which contains signals such as the SERVICE ENGINE SOON lamp.
Any other questions?? :D :D
The painless harnesses are labeled for convience, making it much easier, and all the connectors have longer leads.
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