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Author Topic: 86 2.5L to 88 2.5L swap.  (Read 15073 times)

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Justineldridge

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86 2.5L to 88 2.5L swap.
« on: December 10, 2019, 11:32:04 pm »
I have an 86 fiero with an Iron Duke engine that overheated and blew up 6 years ago. It had been rebuilt and had probably 200k on the engine. I recently bought an 88 iron duke to swap without realising the differences. I understand that the 88 has coil packs instead of a distributor so I'm wondering how many parts will need to be exchanged from an 88. I also did not receive the ecm with the newer engine. I have searched online but found little to no information. Also will the 86 mounts work or will I need to find other mounts from a car similar to the 88 mounts. Any information that you guys can provide will be greatly appreciated. Thanks.
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GTRS Fiero

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Re: 86 2.5L to 88 2.5L swap.
« Reply #1 on: December 10, 2019, 11:38:04 pm »
The ECU, engine wiring harnes, ECU harness, and ECU tray (IIRC) will be needed.
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GTRS Fiero

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Re: 86 2.5L to 88 2.5L swap.
« Reply #2 on: December 11, 2019, 07:47:10 am »
Thinking about this, would you post pics of what you did get?
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Fierofool

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Re: 86 2.5L to 88 2.5L swap.
« Reply #3 on: December 11, 2019, 08:25:15 am »
If you got the engine, hope you got the whole engine harness, including where it connects to the C500 and the ECU.  As GTRS says, you will also need the ECU for a vehicle with your transmission and the mounting tray for an 87 or 88 Duke.  Motor mounts are the same, I believe, at least at the transmission end because they bolt to the transmission.  According to The Fiero Store, the 86-88 front mount is the same, too.  You should be glad.  They are asking $321 for it. 

Maybe TopNotch and Raydar will pick up on this.  They're most familiar with the 88 Duke. 
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Justineldridge

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Re: 86 2.5L to 88 2.5L swap.
« Reply #4 on: December 11, 2019, 11:01:23 am »
I did get all of the engine wiring harness. And I will post pictures to document the whole process. I will be starting early next week. Thanks for all the input guys.
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TopNotch

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Re: 86 2.5L to 88 2.5L swap.
« Reply #5 on: December 11, 2019, 11:12:08 am »
Yes the tray that holds the ECU (ECM) is different. In fact, it's the same tray that's needed for the 7730 type that is used to upgrade the V6. Also, the 88 duke Fiero uses a V5 AC compressor, and is wired to work with that. If your 86 Fiero has the HR6 type compressor, I'm not sure how that would work.
Edit: The 88, I think, uses a different mount beneath the engine itself from the 86. The transmission mounts should be Ok. Also, the 88 uses a single serpentine belt for everything (no separate belt for the AC compressor), with a tensioner that is somewhat hard to find these days.
« Last Edit: December 11, 2019, 11:37:41 am by TopNotch »
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GTRS Fiero

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Re: 86 2.5L to 88 2.5L swap.
« Reply #6 on: December 11, 2019, 05:42:07 pm »
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Fierofool

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Re: 86 2.5L to 88 2.5L swap.
« Reply #7 on: December 11, 2019, 06:51:12 pm »
Just remembered, you will need a neutrally balanced flywheel if you have a manual transmssion or a neutrally balanced flex plate for an automatic.  Hope that came with the engine. 
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Justineldridge

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Re: 86 2.5L to 88 2.5L swap.
« Reply #8 on: December 13, 2019, 12:19:12 am »
The engine came with everything attached. The flywheel was attached but I'm not sure if it had an auto or manual trans. Mine is auto. It still has the compressor and serpintine belt on it.
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Fierofool

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Re: 86 2.5L to 88 2.5L swap.
« Reply #9 on: December 13, 2019, 08:41:23 am »
If it came from an automatic, the flexplate will have a lot of openings in it with no smooth surface for a clutch plate to run against.  It will be pretty light weight.  A flywheel is a pretty good chunk of steel and is solid. 
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There are three kinds of men:

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2.    The few who learn by observation.
3.    The rest of them have to pee on the electric fence and find out for themselves.    Will Rogers

TopNotch

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Re: 86 2.5L to 88 2.5L swap.
« Reply #10 on: December 13, 2019, 10:16:51 am »
I'm pretty sure that all duke flywheels were the same. All neutrally balanced. So the 86 flywheel should be Ok.
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Fierofool

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Re: 86 2.5L to 88 2.5L swap.
« Reply #11 on: December 13, 2019, 10:39:20 am »
Rock Auto does list the flexplate for both the 86 and 88 as being without a weight, so they seem to both be neutrally balanced.
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There are three kinds of men:

1.    The ones that learn by reading.
2.    The few who learn by observation.
3.    The rest of them have to pee on the electric fence and find out for themselves.    Will Rogers

TopNotch

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Re: 86 2.5L to 88 2.5L swap.
« Reply #12 on: December 13, 2019, 12:24:09 pm »
One other important thing: The Fiero Store lists different crank shafts for standard and automatic transmission dukes. I don't know why this is, but if it's because the flex plate and flywheel mount differently to the crank shaft, then your new engine should come from a car with the same kind of transmission as your old engine. Otherwise, you may have to change the crankshaft. I have only dealt with a standard transmission duke, so I don't know about this.
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GTRS Fiero

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Re: 86 2.5L to 88 2.5L swap.
« Reply #13 on: December 13, 2019, 10:08:11 pm »
As best as I can tell, it has to do with the clutch pilot bushing.
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Fierofool

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Re: 86 2.5L to 88 2.5L swap.
« Reply #14 on: December 13, 2019, 10:44:27 pm »
Fieros don't use pilot bushings.  Bushings are only used on input shafts that arent supported on the other end.  Though a Fiero kit comes with a bushing, it's because the kit fits other applications.
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There are three kinds of men:

1.    The ones that learn by reading.
2.    The few who learn by observation.
3.    The rest of them have to pee on the electric fence and find out for themselves.    Will Rogers
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