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Swapping in a DOHC motor


DakotaMatt

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I’ve decided to swap my 3.1 for a 3.4 DOHC. I found a car to pull the motor from that is just like mine, only with the 3.4. I’ve got an auto, cruise and ABS, and so does the other car. I want to make sure I get everything I need with the engine to swap the DOHC into my car, so I came up with a list of parts to get with the motor:

 

Complete engine, with heads and manifolds

Motor mounts

Engine wiring harness

Accessories, such as power steering pump and alternator

PCM

 

Is there anything I’m missing? I figure I can get just about anything I need off the car for one lump deal price, so I’d hate to forget something and have to buy it later. I am going to buy new hoses, timing belt and tensioner, etc.

On a side note, I can get a set of 96 DOHC heads and intake manifold for pretty cheap. I have heard the 96 intake manifold flows considerably better than the 94-95 manifold, and the heads perform better too. I have also heard that by putting 96 heads on a 94 lower end, I create about 10:1 compression. Has anyone done this? Does anyone have an opinion one way or another?

Thanks guys,

Matt

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well.. all i can say is i hope you like working on this peice of $%^& motor.

the intakes only have a 5hp increase over 94-95 and as far as i can tell that claim might bet temperature based. due all the places air can flow around the intake lines. The heads are different from previous years with Less cleance for the valves meaning broken belt = death to motor. Other then that the compression ratio is the same. its been reported that the 90-93 the manuals had higher compression around 9.75:1 where autos were 9.25-9.50:1

 

asfar as your wiring i would assume it would be close to the same but dont count on it.

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I don't mind working on my cars. I have a few others to drive, so I'm not really worried about the higher maintenance a 3.4 requires. I would say since I’ll have the motor out of the car, and the 96 intake is cheap, 5hp is worth my time. I understand that since the combustion chamber is smaller, there is less clearance to the valves. I also would think that with the taller piston height a 94 lower end yields, and a smaller combustion chamber thanks to the 96 heads, I’ll get higher compression #s. I was just wondering if anyone had done the head swap before, and if anyone had any items to add to my “pull from donor car†list.

Thanks again,

Matt

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if u go with a 94+ engine, use a 91-93 harness, i think the 94+ harness on a pre 93 car has a slightly different fuse box configuartion, but i might be wrong. Im doing the swap into my 90 right now and im having fun with making my own shit (wires, hoses, etc etc)

 

-Jeff

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Good to see someone else in the same boat as me :) I think I know what you're talking about, with the fuse boxes being slightly different between 93 and 94. My lumina is a 94, and the new motor/donor car is a 94. Do you think I should still have that problem? I was hoping the harness would plug in to the firewall and the few other places just like it was meant to, with perhaps a bit of fiddling.

 

You know what I found works good for custom hoses? Go to Murry's, or Autozone, or really any auto store, and ask to wander through the back section of hoses. I can usually find a hose to fit my application, no matter how strange it might appear at first.

 

Matt

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Good to see someone else in the same boat as me :) I think I know what you're talking about, with the fuse boxes being slightly different between 93 and 94. My lumina is a 94, and the new motor/donor car is a 94. Do you think I should still have that problem? I was hoping the harness would plug in to the firewall and the few other places just like it was meant to, with perhaps a bit of fiddling.

 

You know what I found works good for custom hoses? Go to Murry's, or Autozone, or really any auto store, and ask to wander through the back section of hoses. I can usually find a hose to fit my application, no matter how strange it might appear at first.

 

Matt

 

Anyone can BUY the shit they need, id much rather fab sumthing up that looks good and works better then stock. 94- 94 should work perfect with the fuse box, im going 2 need 2 rewire my blower motor for sum reason *shrugs*. should be as simple as bolting in, pluggin in and going. your going 2 need 2 fab up p/s lines or buy 3.4 1s. going 2 need about 3" of heatercore hose from the waterpump to the stock location, the rad hoses, and i wanna say a drivers side axle, but tripple check that.

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I went to Autozone.com and checked the driveshaft part numbers. The driver's side at least matched between my 3.1 auto and a 3.4 auto. In fact, it didn't even ask auto or manual. I'll make sure to snag the PS lines though, thanks for reminding me.

I would agree making stuff yourself is better than just buying it if you can make it perform and look better. I like stuff to look factory though, and find it hard to get that mass-produced look when making something by hand.

Matt

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1: use the harness from the donor, itll plug right in. your tach will have too low a redline but that can be solved with a 93-94 Z34 cluster.

 

2: axles are the same

 

3: get the heater hoses/lines from the engine to the firewall, and get the AC lines off the compressor.

 

4: the 3.1 radiator hoses work if you trim them shorter.

 

looks like youve got the rest covered.

 

oh ya BUY A VERY GOOD ALTERNATOR AND PUT IT ON BEFORE YOU PUT THE MOTOR IN THE CAR.

 

 

as far as the "well.. all i can say is i hope you like working on this peice of $%^& motor" comment, thats retarded, and someone has their head up their ass. anything is going to break eventually if you race it. and it looks like he pounds the hell out of his high-ass-mileage car.

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Action shot #1 : I got outbid on the 3.4 I was trying to win on ebay so..... looking for another way to get one. I guess a friend of mine has some 0mi motors that were donated to a school or something stupid like that... I'll let you know what's going on. Needless to say, I am very bummed. I, of course, will take photos of before, durring and after the swap, whenever that happens.

Thanks guys.

Matt

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Yea, I'm checking all the local venues. I have found a couple low mile and a few 0 mile motors, and even some 284s... I am doing the 3.4 for sure, not sure about the manual swap. How weird would that be? Base model 4dr white lumina, with fog lights and Z34 wheels, otherwise stock, with a 284 / 3.4 combo. MAN! I mean, I've got the frickin' 40/60 bench!!! I'd have to grab snot-loads of parts from a 284 car to get that to work, not to mention buckets and a console. I'll keep you guys updated. We all know I'll need help with this one.

 

Matt

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well.. all i can say is i hope you like working on this peice of $%^& motor.

the intakes only have a 5hp increase over 94-95 and as far as i can tell that claim might bet temperature based. due all the places air can flow around the intake lines. The heads are different from previous years with Less cleance for the valves meaning broken belt = death to motor. Other then that the compression ratio is the same. its been reported that the 90-93 the manuals had higher compression around 9.75:1 where autos were 9.25-9.50:1

 

asfar as your wiring i would assume it would be close to the same but dont count on it.

 

i thought '96-97 had a higher compression than '91-95. actually, im pretty sure they do.

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well.. all i can say is i hope you like working on this peice of $%^& motor.

the intakes only have a 5hp increase over 94-95 and as far as i can tell that claim might bet temperature based. due all the places air can flow around the intake lines. The heads are different from previous years with Less cleance for the valves meaning broken belt = death to motor. Other then that the compression ratio is the same. its been reported that the 90-93 the manuals had higher compression around 9.75:1 where autos were 9.25-9.50:1

 

asfar as your wiring i would assume it would be close to the same but dont count on it.

 

i thought '96-97 had a higher compression than '91-95. actually, im pretty sure they do.

 

Yep, they do. But, if you get the pistons out of the 5-speed engines, your compression may just be a bit higher :wink:

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man if you're gonna go through all that work...just get a 3800 series II (with or without a supercharger)...faster, cheaper after installed...and more reliable...but this is a little easier.

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94CutlassSLCoupe - Funny you should say that... I put a 3800sc series II into a 96 Cutlass Supreme about 3 years ago for a friend. It was even your color. It was decently fast at a 14.000s 1/4, but I'm not doing this just because I want to go fast. I'm all about the WOA factor, and I have a thing for 4 cam motors. They're amazing cool in my book. I've got another project going right now, an Intrigue 3.5 into the back of my Fiero. It's comming along, has been all summer if you know what I mean. At least the 3.4 won't need custom engine mounts, a fully hand crafted engine harness, etc. etc. like the Fiero project. It all comes down to this: I'm weird, and this is just what I want to do, i guess :D

Matt

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I found another 3.4 car! I’m buying the entire car this time, so I’ll have all the little odds’n ends. I want to be 100% certain before I drive to BFE to get this thing though; If a W-body has a 3.4 DOHC, it only comes with a 284 right?

I’m looking at a full rebuild on the engine and transmission before I even think about putting them in my Lumina. I also need a clutch. I know 284 clutch options are limited… I can get one through AutoZone for $175ish. Is there a clutch that would work better? I’ll need to replace the 3rd gear syncro, that’s all I know for sure without cracking the case. Where can I go for 284 parts, besides a junkyard?

 

Matt

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All 5-speed 3.4 DOHC's came with the 284 yes.

Sounds like an awesome job man...I can't wait to see the results.

You should buy my car from me, too bad it has the 4T60-E and not the 284... :roll:

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I guess i understand where you're coming from now...but people who know w's will probably go whoa more to a 3800 car than a 3.4 dohc...or atleast i would....

 

....If i had a place out here in Mich where i could do some swappin' i'd be building a 3800sc Series II cutlass coupe (but not with my current car)

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There is a local GTP group that congregates at a nearby diner every week. My Cutlass friend and I went to a few of their meetings, and while some of them were curious about the swap, it wasn't as big a hit as I would have expected. Honestly man, almost every high end FWD GM car comes with a 3800 now. The 3.4 DOHC is like the dark horse of the GM powertrain world. Only 3 cars got it, and unless you're into the motor, almost nobody outside of W-body owners know what the potential is. When you pull up next to some honda or focus in a 97+ GTP, they look the other way and drive off with their tail between their legs. It's even funnier when you find yourself next to one in an F-body. But when you get the chance to line up next to some punk, and you've got a car they totally underestimate, (like my parts-getter car, a 97 olds silhouette), the end result is a thing of beauty. I love to shock people like that. I mean, everyone expects you to outrun a SVT focus in a SS, but when you pull it off in a minivan, or a 3.4 lumina, that's doing it with style :wink:

Matt

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There is a local GTP group that congregates at a nearby diner every week. My Cutlass friend and I went to a few of their meetings, and while some of them were curious about the swap, it wasn't as big a hit as I would have expected. Honestly man, almost every high end FWD GM car comes with a 3800 now. The 3.4 DOHC is like the dark horse of the GM powertrain world. Only 3 cars got it, and unless you're into the motor, almost nobody outside of W-body owners know what the potential is. When you pull up next to some honda or focus in a 97+ GTP, they look the other way and drive off with their tail between their legs. It's even funnier when you find yourself next to one in an F-body. But when you get the chance to line up next to some punk, and you've got a car they totally underestimate, (like my parts-getter car, a 97 olds silhouette), the end result is a thing of beauty. I love to shock people like that. I mean, everyone expects you to outrun a SVT focus in a SS, but when you pull it off in a minivan, that's doing it with style.

Matt

 

 

Thats awesome man. The 3.4 is considered the black sheep of the GM engine's.

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