RE: swap questions
I cannot take credit for this - I found this on another forum.
3.9L to 360 or 318 Swap
92 up motor mounting is the same in a Dakota.
As long as you stick with a V6 or V8 trans, they will all bolt up to a 360
V6 and V8 radiators are the same
1. Engine- Find one with the lowest mileage. The multi-port magnum 360 motors, like what you have now, started in 1993. You can use one from a Full size dodge (94 up), Durango, or Dakota. You will need a complete motor from intake to pan. You must use a Dakota (small sump oil pan in order for it to clear the cross member and the oil pickup is different, they are pan style specific) The Full size dodges come with a larger pan and they will not work. In later years, the intakes have less and less vacuum ports on each side of the intake. You may need to piggyback some for a 92-93 or go ahead and buy the M1-2bbl intake.
2. Find a 92-93 V8 fuel rail, the pressure is regulated on the rail unlike later years. They are regulated in the pump. If you can’t, convert your truck to a 94 up fuel system and worry about the return line when your making about 400 RWHP.
3. V8 Throttle body. They are 92-93 specific for the cables to hook up.
4. Injector wiring- If you can find a V8 harness (YOU ARE THE MAN, because I think someone wiped them off the earth and they are $1100 new) The only difference is 4 wires. Look at your injector wiring. There is a green and orange wire that loops all 3 injectors on each side. You need to splice into that and add one more to each injector run for injectors 7 and 8 that are coming. That is the positive connection for the injector so it can be looped. Each injector fires on a negative signal from the computer. You need to run 2 wires from the injector line to the computer (one each for injectors 7 and 8) to their respective pins on the computer. This is the only difference in wiring between a V6 and V8. You are adding one injector to each side at closest to the firewall. This means the other 6 are moving forward. I had to lengthen two of them on the right side.
5. Flex plate- Find one from a 93-95 360. You must run a 360 flex plate because it has a weight on it to balance the motor. If you can’t, find a 96 up one but it will only bolt to a 96 and newer torque converter.
6. Transmission- If you stay with the V6 tranny (A500) it may not hold up as well as the V8 tranny (A518). If you can only find a 96 and newer flex plate you must run a 96 and newer torque converter. To do this you will have to change the front pump gears of the trans to accept the 96 and newer torque converter. The 95 back ones are different. If you find a 92-95 V8 trans (GOOD LUCK, AND AGAIN YOU WILL BE THE MAN, because they seem to have been wiped from the planet) the gears in the trans are all the same, but you will still need to match the years from flex plate to torque converter so they will bolt together. If you do find a V8 trans you will need a different driveshaft. They are shorter than the V6’s. IMPORTANT- Depending on the year of the engine you go with, and I cant tell you what years are like this) and if you stay with the V6 tranny, you will need to grind a small corner of the block down in order for the starter to rotate into the hole of the trans. This is not a big deal. I’m only talking about a little bit of material from where the factory uses a boss to support the block while drilling. If you find a V8 tranny this won’t be an issue.
7. Find a V8 fan shroud or cut yours down by about 4-5 inches. Putting in an electric fan will increase your horsepower, you can find wiring instructions online.
8. Exhaust- The 92-93 exhaust manifolds have bigger outlets than 94 up. This is better. You probably need to find 92-93 manifolds so your current y-pipe will bolt up without leaking. The 94 up ones will bolt up but your y-pipe flanges may be a little too big and it might leak. I’m not saying it will but it may. Single or cat back exhaust is recommended until you are making at least 300 RWHP.
9. Stick with a 92 water pump, and make sure you use a 360 harmonic balancer because it balances the engine. Your V6 and a 318 one is the same but a 360 is different. Check the bolt holes for the under drive pulley to bolt up. On really late model engines, they don’t run the same balancer and pulley as you have now. Stick with one from 93 to about 98 or so and they are all the same.
10. V8 distributor and wires. You can find one out of a 92-95 Dakota with a 318 in it, OR anything out of a 94-97 dodge ram will work too. Nothing later than 97 will plug in. The timing curves are different between the Dakota and Ram, but either one will work
11. ECM- Computer. You will need either a 92-95 Dakota ECM or a 94-95 Dodge Ram ECM. Nothing later than 95 will work because that is all OBDII. You have OBD I. I would recommend getting a 94-95 Ram computer because you can get it for a 360. The Dakotas only had a 318 in them. Plus you can buy a Performance computer for the 360 Ram, which is made for a 360. Either computer will run the truck fine, I have ran both but I haven’t played with either of them to see which one makes more power.
12. Sensors- depending on what year motor you buy, you will have to go with 97 back sensors in order for them to plug in. It is recommended that you use the ones you have now because you know they work. Block off the EGR. Some 93-95 Full size Ram Vans had block off plates for the intake manifold. If you can’t find one, make one. You will need shorter bolts because the ones holding on the EGR valve are too long for a plate. Leave the EGR solenoid plugged in and tie it up out of the way. This will eliminate some vacuum lines too.
Last edited by Crazy4x4RT; 10-26-2008 at 12:44 PM.