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3.1 mpfi to dohc 3.4 swap



Ok guys.... You ready? Time to start the swap. I have everything unbolted except for the downpipe bolts but I can still explain the process to pulling it out. These basic steps work for any fwd gm swap.

Step 1. Remove battery and fluids.
Step 2. Disconnect wiring harness at all points to the body.
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Step 3. Jack up front end and remove the front tires.
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Step 4. Pull calipers,caliper mounting brackets and rotors off.
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Step 5. Unbolt hubs and pop out halfshafts from trans and remove assembly.
Step 6. Unbolt exhaust pipe from manifold.
Step 7. Remove plastic dust cover on drivers side covering the trans mount.
Step 8. Unbolt the drivers side trans mount(as shown).
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Step 9. Remove plastic dust cover on passangers side
Step 10. Unbolt passanger trans mount(from bottom of k frame easier access)
Step 11. Hook your hoist as shown to the factory assembly crane brackets.
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Step 12. Hoist it up and out.
And the engines out.... My next post should be of the install.
 
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congratulations, good to see the progress. saw some 3.4's at the junkyard recently...i must say im very tempted lol.
 
ctracer said:
congratulations, good to see the progress. saw some 3.4's at the junkyard recently...i must say im very tempted lol.
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Just make sure you can dedicate yourself to maintaining it. You gotta do the routine maintance or it will die. Especially the timing belt and the tensioners for it. I just bought a chiltons(their not the best help but they have needed specs and diagrams) and it has helped so I would suggest getting one of those. Their very needy motors but if you treat them well, they will treat you equally well.

Also make sure its a early monte carlo or a grand prix or else the wiring harness wont plug into the body harness..... Forgot the question you asked and for now I'm just using the 4T60E that the engine came bolted to already until I find a 6 speed.
 
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bluegtp91 said:
4T60E, yay.

Holds 150FWHP and explodes everywhere.
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My thoughts exactly :/ but eh the trans was free with the motor so it'll do for now. Will also do for the how-to. Maybe I will do a how to convert to manual later on down the road.
 


Also heads up for anyone swapping from a 3.1 mpfi the exhaust flange will not bolt to it you will need to get a flange off a monte carlo or cavalier. Went and got one from the junk yard(looks like crap and was hacked apart at one point but the part I need is intact.
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Top, 3.4 exhaust. Bottom, 3.1 exhaust. .5 inches difference between the two.
 
Havent been on in awhile due to work and working on the car but got a bit of progress done... and its almost ready to be dropped in. All I have to do is make new fuel lines because the parts I need are discontinued(will post pieces required incase anyone has to replace that line).

Ok.... back to the swap.... heres how the wirings run....

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Side note.... I picked up a strut bar off a cutlass supreme convertable...

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Well... I found out exactly why noone does this swap.... But it will not deter me... The factory dash wiring will not work in my 91 with the 95 I put in it. I'm in the process of looking for an obd 2.0 dash with all the wiring intact.
 
yeah they are different dashes. any obd 2 wbody with the 3.4 will provide it. or maybe you can look for an early car with obd1 that came with the 3.4.
 
ctracer said:
yeah they are different dashes. any obd 2 wbody with the 3.4 will provide it. or maybe you can look for an early car with obd1 that came with the 3.4.
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Actually only has to be obd 2.0... I'm preferably looking for a 95 cuz its out of the same gen as mine but any will do. Was looking into a g6 gxp dash but dont think itll fit. Also if i can't find a 95 I might get a 98 gtp dash with the diagnostics screen on it.
 


Didn't mean to leave you guys hanging but the engine is in and had it cranking by jumping the starter to the battery.... Gotta wait on a dash but once thats done it will be running again. Heres pics of it in....(also the how to kinda went out the window as well sorry lmao)

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Heres putting it in.

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Also anyone know what this plugs into? I believe its to the abs module which I don't have but I'm not sure.
 
yeah the grand prix is on hold for the time being... i picked up a new dd project atm thats on priority on basis that its running... its a 1984 f150 straight 6 300ci with a 3 speed
 
A 1980 chevy monza towne coupe. It has a buick 231 and a 4 speed. Im actually looking to part it out or scrap it one of the two.
 
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Update on the build.... She lives!!!! Got her fired earlier... Didn't have to rewire the dash... Just one wire...Tip for anyone upgrading engines to later years... If you do the swap and it will not crank, no dash power, not much of anything... try running a power wire from the battery to the ecm and try firing it like that... if that works then you can do like I'm doing and using that wire as a kill switch... or feed that wire into the ignition power off the column.
 
91gpse said:
Update on the build.... She lives!!!! Got her fired earlier... Didn't have to rewire the dash... Just one wire...Tip for anyone upgrading engines to later years... If you do the swap and it will not crank, no dash power, not much of anything... try running a power wire from the battery to the ecm and try firing it like that... if that works then you can do like I'm doing and using that wire as a kill switch... or feed that wire into the ignition power off the column.
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yes! congrats!
thanks for that bit of information.
 
ctracer said:
yes! congrats!
thanks for that bit of information.
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Just to try it to see if it worked, I ran a wire from the battery to the ecm fuse in the engine compartment. And it worked... Only issue I have now is the fuel line is leaking and when the fuel hit the flames out the header it burst into flames lmao good thing we had a fire extinguisher or bye bye gp -,-
 
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