Here is a little information I would like to share that I have discovered by accident....

....this head can be found on 1990-1993 S-10's, S-15's, Blazers etc...

a nice upgrade option for those interested in better flowing heads for 87 and 88 Fiero with the Iron Duke 2.5.

....while this option may not produce incredible horsepower like expensive, hard to find, race only Super Duty 4 heads.......they did produce to my surprise a noticeable improvement in both torque and fuel economy over the stock Fiero heads.
will post some pics in a few minutes.....

[This message has been edited by v8fiero400 (edited 06-09-2006).]

Here is a shot of a 1988 Fiero head next to a 1990 S-10 head ....... as you can easily see, the exhaust ports in the S-10 head are D shaped. Although smaller they flow better and more efficiently with less reversion back into the cylinder during the end of the exhaust stroke......The good news is that the exhaust manifolds and gaskets on these two cars are exactly the same and interchange!

[This message has been edited by v8fiero400 (edited 06-09-2006).]

the oil and coolant passages line up?

Here is a shot of the intake side. According to GM, the newer heads have redesigned cooling passages and are less prone to cracking...... the bad news is that the bolt pattern is different and the Fiero intake manifold will not bolt on the newer head.

It should also be noted that the 'duke that head came off of is stronger than ours as well. A 1993 S10 'duke would give you a reliable 100 and some HP, with a little more room for safe improvement. Of course it seems silly to use a 'duke for an engine swap, but their gas mileage is quite good...

You could almost theorize that the Fiero exhaust ports were too big and it lost too much bottom end and that it had to run too rich to compensate for the big exhaust where as on the newer motor, you have a smaller exhaust and better combustion maximizing torque and HP but the potential probably isn't as high without serious porting.

However, if you stick in a Super Duty crank, then you may need to port that exhaust back out to look like the Fiero one to handle the extra displacement.

Maybe someday I'll get a 4 cylinder and start experimenting with that like I have been with the 6cyl and 3.4...
Ofcourse my thoughts on the 4 cylinder cars is that they make ideal 4.9 motor frames. To me it's not worth going from a 3.4 to a 4.9, but a 2.5 to a 4.9 is a different story... However taking a 2.5L to 3.3L sounds interesting...

Hey v8fiero interesting find. Have you seen any actual numbers on the flow of this head or are you going on your in car experiences. I've thought about building an 87 dis motor and this head might be just the ticket. JM

Looking at the top of the intake, you must have an 87 or 88 duke with the 700 series TBI? The 84-86 300 Series won't bolt up to that intake

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1984 Fiero SE

interesting.

93 S-10, Has anyone done this swap? Are they direct bolt in. Or is the stater on the wrong side? do they still use the force balancer?

This is a great thread, bump to the top....

I see you mentioned S-10 heads...... are the grand am-ciera heads better also?

One warning... make sure you are all looking at R vin engines.

I'm told the U vin engine has a number of differences that make various parts so they won't fit.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
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Thats correct..... the head bolt pattern for some of these engines has a different pattern and some heads will not bolt onto the fiero block.

Keep in mind most of this specific post is for 87 and later L4. As many know, the L4's had multiple major changes in 87-88 that carried thru End Of Life for this engine.

Overall I find this an interesting thread. I've looked at the truck R vin engines and there are some similarities but there are also major differences.

The truck starter is on the right side. I don't know if the block is drilled/tapped on both sides. I didn't see the side sadle outlet for the water pump on the few truck blocks I've had a chance to look at in the last couple years. The 87 and up trucks I did see also used an ECM controlled EGR but w/o the problematic vacuum switch on the Fiero V6. (the trucks don't use the car ECM either...)

I'm told the U vin engine is shorter than the R. I have not been able to look into that. It may be possible to put an entire U engine into Fiero, but if the engine is shorter, little mechanical will interchange from an R to U or other way round. (electriaclly the R and U seem to use the same sensors, TBI, etc for any given year.)

Using an entire U engine in a Fiero may not be a bad plan... The R fits fairly tight. It's barely shorter than a V8 when it really comes down to it. A U vin may make you make some brackets but I think U vin was used later than R. (R was used thru only about 1992.)

The later R's and U's were rated for about 110-120HP. Keep in mind that besides the mechanical changes in the later engines, there may have been ECM code changes along with them. That means even if you put a 110HP R into a Fiero, you may not get 110HP using Fiero ECM code.

Assuming that the later engines use the same ECM as 87+ Fiero (1227748) L4... it is possible to use the ECM PROM from at least some FWD cars. Exactly how you do that is determined by which VSS the FWD car used.

i have heard of people using the truck engines because of the similarity to the SD block. the casting is the same, however the metallurgy is not. something about no nickle content in the s-10 block...

i cant see why you wouldnt be able to redrill the starter hole. dont they do that on the 3.4 pushrods?

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Brandon Edmonds

1996 Taurus SHO (my baby)
1986 Fiero (parts car)
1984 Fiero (bare rust free frame)
1998 Suzuki Katana 750 (not too shabby if you ask me)
1993 Taurus SHO (in pieces till i get a tranny)

Here is an intstalled pic of the head and intake swap....



Parts used...

1992 Chevrolet S-10 2.5 cylinder head
1990 Pontiac Grand AM intake manifold
use stock Fiero head and exhaust gaskets... use Grand AM intake manifold gasket
and a set of slightly longer pushrods MPR-309 (Autozone)


The results were better than I thought...... The car has better throttle responce than before and noticably better acceleration.

How much did all this cost? Did you find the parts locally?

The S-10 not having the internal ballancer is a Good thing. You'd agree if you had one fail and throw a rod through the crankcase due to oil starvation.

quote Originally posted by TejasFiero: How much did all this cost? Did you find the parts locally?

Head was $45 at pick-a-part
intake was $20

it was actually more expensive to get all the gaskets for the conversion

Do you have a casting number for the S-10 heads? Thanks!

quote Originally posted by JAL: Do you have a casting number for the S-10 heads? Thanks!

Cast #485-514

The VIN U engines from Grand Am's and Calai's will not bolt up to a Fiero. I bought one from a 86 Buick Sommerset a few years ago to bolt into my 86 Fiero, this one looked good, had a new head. Once I got it home, I noticed a big problem. The mount points for the engine mount u-bracket thing were not there, only 1 out of the 5 were there, so the only way to get it to work was to make custom mounts. So I returned the engine. Also, I heard that the VIN U engines are not as strong as the VIN R Fiero engines.

And vin U engines do not have the improved head design either.

stay away from VIN U engines!!!

Wish I'd known this a year+ ago when I was looking for a head for my 87. Now I've got a fully rebuilt 87 engine sitting on the engine stand waiting for me to get the remains of the old one out of the car. After getting the core head and then the block, I'd started wondering about using an S-10 engine for improved strength, but didn't know what differences I might run into besides redrilling the starter holes in the block.

Thanks for the good info. If I come across a later head and intake I might just swap over.

This is great news. I'm buying an 87 coupe with a rod knock, and getting some good condition crank/rods/pistons, putting in new bearings and rings, and I was wishing I could find out what made the 93 motor make more power and fuel economy, as I haven't been able to find a good 93 motor.

Excellent information, and greatly appreciated since I'm going to open my motor up anyways.


edited to add; do you have to use a grand am intake or was that just what you could find?
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96 Saturn SL2 Turbo (evil SL2)

My cardomain site: cardomain.com/memberpage/702872
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[This message has been edited by cooguyfish (edited 10-30-2006).]

could any of this info work on the "Big Bad Duke"?
...just wondering!

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John DuRette
Custom 85 SE/87 Coupe
"Kinda makes you nostalgic for a Members Only jacket"

Bump, to add this to my favorites...

Better flowing bolt on Duke heads??? I understand that the head from the super duty 4 will bolt right on. Flows better than any other four cyl head so much so that a new less restrictive intake manifold and throttle body will also be needed.

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87GT 3.4 Turbo- 0-60 5.2 seconds -Best
Engine Controls, ECM goodies, Chip
re-programming & odd electronics stuff

quote Originally posted by Dennis LaGrua: Better flowing bolt on Duke heads??? I understand that the head from the super duty 4 will bolt right on. Flows better than any other four cyl head so much so that a new less restrictive intake manifold and throttle body will also be needed.

See author's first post.

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My Web page | The Turbo Super Duty Build.
You know that little voice that says it can't be done? I duct-taped mine's mouth shut and pushed it down a flight of stairs.

are there any alternatives available for the earlier dukes? Would love to do an SD4 conversion, but every now and then reality decides to let me know I'm dreaming
What about v8 heads? anything there we can use for the duke?

quote Originally posted by PerKr: are there any alternatives available for the earlier dukes? Would love to do an SD4 conversion, but every now and then reality decides to let me know I'm dreaming What about v8 heads? anything there we can use for the duke?

On my first Fiero (an 84).... had an engine fire. Luckily I was able to put out the fire before it burned the entire car..... but much of the wiring and fuel injection was toast.

It was my only car..... so I took a trip to the junkyard and got an intake form a 1980 chevy citation 2.5 and installed it with the 2 barrel carburetor..... and along with the HEI distributor, I was able to totally eliminate the computer.

It actually ran stronger that when it had the TBI...... although fuel economy did suffer a little.

Good thread

wow, excellent thread, thanks for sharing the info. I'm about to completely rebuild my 4banger this year after it was standing for 4 years now since i bought my station wagon, and as used fiero parts are completely inaccessible in europe, every swapping-reference comes handy.

Wow great thread!! Great news for us 4 cylinder owners!

Hmm...you make me wish I actually had free time :P. Awesome information regardless. I'll give you a thumbs up for this one.