[thebigblueox]

How easy is it to swap a 4brl in place of my TBI unit. can it be done? what do i need? how do i bypass the computer? the truck is a 91'.Thanks!

 

[Guest]

Main issue with the computer is tranny control regarding the converter lockup and overdrive. This can be controlled with two toggle switches, or a controller that JVX sells. Orrrr, get a non-lockup overdrive tranny, then you have one toggle switch, orrrr swap in a 3-speed. The fuel lines are easily dealt with. Just get a single inlet, dual outlet pressure regulator. The second outlet can function as the fuel return line. Basically, it you keep the electrical wiring intact, you'll have your AC and other functions, as well as fuel pump. I hear tell that there's an external regulator available to bypass the computer as well, but have no specifics. You'll need to tie in a pre-TBI style ignition system. Hell, I used an old single-point unit for a long time til a more modern one was available to me. Naturally, the computer put the "check engine" light in permanent "on" position. I decided I'd wait it out. Without TPS and MAP sensor inputs, I'm afraid the stock ignition system would not function properly, but do not know for sure (maybe in limp-home mode). I didn't check it then. According to my '89 FSM, the SMEC determines ignition advance based on coolant temp, engine rpm, and available manifold vacuum, so it would seem to imply it would run properly. At the time, I just didn't have the time to play. I knew the old stand-alone would work.
Be sure to make sure the tranny kickdown linkage is retained and functional when you swap. Ya gotta have that or the tranny is toast.

 

[SeahawkDodge]

I think the biggest question should be "Why?" I don't know why you would want to swap to a carb. The carburated engines put out less horsepower and get worse gas mileage than the fuel injected ones. In addition, the TBI has a huge advantage offroad.

If you really want to do it, then you will need a new distibutor, ignition system (wires and ignition module) and the carb. You will also need an external voltage regulator, since the computer controls that as well.

 

[lovemydodge]

i'm doing something along those lines...kinda. i'm replacing the 318 in my 78 with a 360 from a 95. why a carb you ask? because i hate having a computer on my truck. i want to be able to listen to the engine and figure out the problem without going through a littany of sensors and relays only to end up going to the dealer. the 360 will have an m1 intake with a 4 bbl. i got a new mp ignition system and electric fuel pump. the only thing i still need to figure out how to do is wire up the overdrive trans from the 95. i also like the sound of a carb opening up

 

[CLRracer]

i have 2 trucks with tbi, and i have never had to take it to a dealer. with a FSM and this site, i havnt had any problems tracking down a problem. and after being off road, u couldnt pay me to switch to a carb. on a street only rig, i may could see swapping to carb, but the tbi would have to be really screwed up. but if u really want to switch, u will need the stuff listed above.

Duane

 

[Guest]

i'm doing something along those lines...kinda. i'm replacing the 318 in my 78 with a 360 from a 95. why a carb you ask? because i hate having a computer on my truck. i want to be able to listen to the engine and figure out the problem without going through a littany of sensors and relays only to end up going to the dealer. the 360 will have an m1 intake with a 4 bbl. i got a new mp ignition system and electric fuel pump. the only thing i still need to figure out how to do is wire up the overdrive trans from the 95. i also like the sound of a carb opening up

Amen Bruddah! Wiring up the tranny is a snap. Just a couple wires and toggles. Basically, you just need to tie into a 12v source and plug into the selenoids for the TC and overdrive. I'll look around and see if I can find the exact way it's done.

 

[lovemydodge]

that sounds too easy. i kept the driving lights and od switch from the 95. wondering if i could use that. thanks for checking

 

[Guest]

I'd think you could use the switch from the '95 without any problem. Just remember that the switch was used to lockout the overdrive. When you punch the button to engage overdrive, the computer still was there to lock up the converter. If you tie both together, naturally, they'll both engage....might be a stout jolt if you are into the throttle pretty good. That's the only advantage I see to using two toggles, but either way, it'll work. Okay, the diagram I have is for the overdrive non-lockup model, but the only difference is the extra switch for the converter. They show a wire from a 12v source with an inline 2 amp fuse. The wire is connected to one pin of the overdrive selenoid. The other pin is connected to the wire that leads through the firewall and is connected to the switch. They actually used a 2-pin connector to plug into the selenoid for a neat installation. Duplicate this for the converter, and you're done. It's that easy. Thankfully, Mopar maintained the 1-2-3 linkage so swaps would be basically a bolt-in (after the floorboards were pounded a bit for clearance. I wonder how well those converters hold up to running unlocked all the time?

 

[lovemydodge]

cool. the 518 is a non-lockup, don't know about the 46rh that i have. mine has a three pin pigtail. guess one is for lockup and one for overdrive and the 12 v source. two toggles might be the way to go. luckily my 78 has plenty of clearance for the new transmission. but the mount is totally different. the old mount is bolted to the top and bottom of the frame while the new one bolts to the side. so i have to box the frame to make it work. thanks for the info

 

[Major Ramifications]

I think the biggest question should be "Why?" I don't know why you would want to swap to a carb. The carburated engines put out less horsepower and get worse gas mileage than the fuel injected ones. In addition, the TBI has a huge advantage offroad.

If you really want to do it, then you will need a new distibutor, ignition system (wires and ignition module) and the carb. You will also need an external voltage regulator, since the computer controls that as well.

The biggest reason I can think of for dumping the TBI is if you modify the engine. The TBI is only one of several reasons why the horsepower and mileage increased a bit in the late '80's. Don't rule out the higher compression, the roller cam, high-swirl heads, overdrive and lockup converters.
The factory 318 TBI system would not be able to compensate for a high output 360 with high compression, ported heads, more radical camshaft, etc.
Not everybody goes offroad, and anyway down here offroad means mud, not hills. The only hills here are man-made ones.
I drove my '89 Ramcharger 318 w/ TBI for four years, and I have never had an engine as slow to respond as that one.

 

[Guest]

Off-roading with a carb is much better when the needle and seats are spring-loaded with off-road kits if necessary. A factory'95 and it's a non-lockup? I know they sell them in the aftermarket chain, but an OEM '95?

 

[thebigblueox]

What happens if i eliminate the computer controlled tranny altogether? what else would i have to do? After that can the ECM be eliminated? what does the ECM controll?