How I can swap 3.9 to 4.6 in 95 D-90? - Defender Source
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  #1  
Old September 10th, 2004, 05:52 AM
Vadim
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Question How I can swap 3.9 to 4.6 in 95 D-90?

I have 95 D-90.I plan to swap 3.9 to 4.6.I don't know if 4.6 will fit stock manual transmision from 3.9.And what else I need to change under the hood or drivetrain?
Thank you in advance for help.
Vadim
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  #2  
Old September 10th, 2004, 04:12 PM
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Doug Walker
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It's a bolt on tranny side. MAF and ECU will work fine, but afterwards you might want to try re-chipping. There's a bunch of stuff to change up front either way. If you're going to keep your 4 pulleys -- new front cover and some spacers. Talk to RoversNorth or BritishPacific, I think they have a kit.

DW
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Old September 10th, 2004, 07:32 PM
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Thank you Doug
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  #4  
Old September 10th, 2004, 09:25 PM
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Doug you're so smart.
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  #5  
Old September 11th, 2004, 02:12 AM
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Matt Hurst
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doug-what do you have to change up front?i used my same front cover and only one spacer.?doug did you do this convert or did some one do it for you?
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  #6  
Old September 11th, 2004, 11:00 AM
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Chris Davis
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I have just finished this swap in my '94 3.9. I had to reuse my front cover so that I could use my pully set ups and I rechipped my computer with the chip from a 4.2. The truck runs great WHEN I CAN START IT! I have been trouble shooting some bizzare problem (it wont start unless I do something like unplug the stepper motor or ground the HT lead...random stuff).

Since you are a distributor driven truck (95's still have distributors?) and the 4.6 is not, you will need a new cam that has a distributor drive. I chose to go with a crane cam but you will have to mill the front of the cam so that it accepts the retainer plate on the 4.0/4.6 blocks--no biggie. Since the 4.6 crank is longer, you will need a spacer to take up the slack between the pulley/balancer and the retaining bolt--just shave the teeth off an extra timing gear and that will work fine.

You can reuse your heads or use the 4.6 heads, but most 4.6 heads have an extra hole by the exhaust ports (EV heads) that will need to be plugged. No big deal there.

I reused my oil pan, which you will probably have to as well, which means you will swap the oil pick-up as well. Also, check you alternator bracket--there is one head bolt by #1 cylinder that has a stud out the top on mine, but not on the 4.6. I reused this bolt so that my alternator bracket would attach. There may also be a couple holes on the front of the 4.0/4.6 block that have not been drilled/tapped for ancillaries (mine had all already tapped that I needed)--again, no big deal, just drill it and tap it (carefully, of course)

I can actually use my 5th gear up hill now!


edit: My starting issue turned out to be the ignition switch and unrelated to the engine install. YEAH, it is running!
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Old September 11th, 2004, 12:47 PM
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I decided to change over to the serpentine, so I used the front cover that was on the new engine and and had to fool with all the other stuff instead (AC, power steering, etc.). So my answer above was only a half educated guess. Davis seems to have covered the waterfront damn well above.

NOTE ON AIR CONDITIONING: I put a used 95 RR R134 Compressor in place of the R12 compressor that was original, then replaced the R12 fluid with R134. It may just be my luck, but my AC is twice as cold now.

DW
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  #8  
Old September 11th, 2004, 03:16 PM
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Peter Sherman
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hey Doug did you fix the ingnition ghost that was a problem for a while.
Peter
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  #9  
Old September 11th, 2004, 03:49 PM
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Doug Walker
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Peter, I'm not sure what you mean. I still have hard starting, but that symtom is that same as before the engine swap. I think I have a valve or air leak somewhere that I haven't been able to find yet. Is that what you mean? The 3200 RPM point where the power curve used to drop off is gone. I'm sure that was caused by a flat camshaft in the old engine.

I want to find a way to get cold air into the engine. Adding a snorkle would work, but then you would have about 6 feet of air tunnel in the engine bay for the air to heat up before it gets to the throttle body!! I don't want to move my filter outside, so the John Lee solution won't work. Thinking of scooping cold air via a hood opening. Anyone have some suggestions?

DW
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  #10  
Old September 11th, 2004, 10:08 PM
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Why not use a similar system as the heater box gets, and just reverse it to the oppossite side. Instead of the flat mesh, use the raised intake that you see in the rover mags. I think that would get cool air in and also have a slight ram air affect when moving, Just might have to add an additional filter when in dusty conditions, I wouldn't think water would be a problem.
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  #11  
Old September 12th, 2004, 03:25 AM
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Jason Herring
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Doug,
I was thinking of doing something similar to what Aaron is suggesting in my truck. I don't want a schnorkel, so I was thinking of a little scoup on the left wing grille. However, I was thinking of facing it backwards so I don't allow the engine to inject bugs/junk from the road/excess dust. Also, I think I'd drill some holes in the bottom of the plastic plenum below the grate to allow water to drain out. If anyone has a source on those inlet cover/scoops or a plenum for the left side could they post it?

I would probably try to relocate the MAF sensor somwhere closer to the throttle body and route some flexible hose from there.

A question for you: does the '95 RR R134 air conditioning compressor bolt up to the engine the same as the stock R12 unit? Are there any special mods involved? I'm going to be installing air conditioning in my D90 and might want to go with R134 if it's an easy mod.
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  #12  
Old September 12th, 2004, 11:30 PM
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Doug Walker
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You have 4 belts. My new rig has a serpentine, like the 95 Rangies and the 97 D90s. I believe the compressor is a shelf item at most AC shops -- they can probably swap you a 134 compressor of some sort. That's probably the simplest thing to do.

Like the idea of the cold air path -- it would be great if someone turns up a plenum!!
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