Well, now that I'm laid up recovering from a heart attack, I have time to write this, about my yellow 88 coupe (Buzz)...
You may recall from this thread that I had acquired a later model cylinder head that I was going to use on my duke rebuild. As it says in that thread, my research showed that the head was a 91-93 VIN A head, and I thought it would fit on my 88 duke block. Well, as it turned out, two of the bolt holes didn't match up. So in true "make it work" fashion, I modified the head as shown in these pictures:

I filled in the old hole with a mild steel rod, and drilled a new hole. The rod is held in with JB Weld. With nearly 1000 miles on the engine since getting it back together, and no problems, I think it worked. Here's the other hole I fixed:


I wanted to use Big Block Chevy roller rockers on the head, so I had to drill and tap the rocker stud holes as shown in these pictures. (The head in the pictures is my old one, which had a crack, but it was good practice.)



Actually, drilling and tapping for the bigger studs was easy. But enlarging the holes in the guide plates was hard -- they are made of extremely hard steel.
The roller rockers I used were some stainless steel ones I found on Ebay. Below is what they look like on the engine. BTW, the pushrods I used for this combination are Melling MPR-389. They are for a late 60's - early 70's Ford V8.


The head was not the only mod I did to the engine. I put in an Accelerated Motion camshaft with a little more lift and duration than stock, and an all metal timing gear set:


I also put on a later model starter to save weight. This picture compares it to the original.

BTW, the new starter works just fine.

Below is the engine back on the cradle, with re-assembly almost finished.

Before I put it in the car, I put in oil, put in the pressure sender, and cranked it over with a battery. A meter on the sender showed I had oil pressure.

Back in the car...

The finished product...


So, you may be asking, "How does it run?" Well, it runs fine, but I'm not sure how much better. Before the rebuild, it would start to run out of "oomph" at 4500 RPM. Now it feels like it has more to go, but I'm afraid to run it up higher. Maybe after I have a few thousand miles on it.

I really like that valve cover. I'm kind of new to this but that iron duke doesn't look like the one I usually see in Fieros. Is that custom or did it come out of another GM vehicle?

EDIT whoops my bad it's just a late model head.

[This message has been edited by ThatFieroKid (edited 09-15-2011).]

Looks fantastic, great job!

The valve cover is a Super Duty 4 cover. They'll fit on a duke, but you have to mod them a bit for emission control ports.
Edit: See this thread to see how I adapted the valve cover.

[This message has been edited by TopNotch (edited 09-15-2011).]

Man Top - Heart attack????? Hope all is well with you and that you are on the mend! Sad to hear it but glad you are still here to post up more great Buzz updates. I love the "make it work" philosophy. It's essential when you own Fiero's....lol. Get well soon!

Pat

I forgot to put in the thread that I had the block bored .040 over while I had the engine apart. So now, it is a 154 instead of a 151. I also had the crank ground.

Yesterday I ran my rebuilt duke briefly up to 5000 RPM. It felt like it still had more to go. Before the rebuild, it used to begin running out of "oomph" at 4500 RPM. 5000 RPM is scarey territory on a duke, but it ran nice and smooth.

Excellent!

Great info. Great pics and a nice job.

Just for grins (bragging rights?) you ought to have it dynoed.
I'm curious what kind of power it makes.

quote Originally posted by Raydar: Excellent! Great info. Great pics and a nice job. Just for grins (bragging rights?) you ought to have it dynoed. I'm curious what kind of power it makes.

I'll second that!
I'm curious to see the numbers.

You have something similar to what I did, but also very different.

It looks like you got a VIN U head. They used the same casting number, but drilled with two different patterns.

If you do another adjustable valvetrain Duke, I got some part numbers somewhere I can dig up so that you don't have to do any drilling, tapping, or grinding of guideplates.
I have Chrysler 383 pushrods in my combo.

Interesting intake adapter, why did you do that instead of getting the later intake that actually lines up?

I also used the Cloyes 8-1016 gears, but I was disappointed to learn upon installing them that they had a great deal more valve lash than the Pontiac spec, and as such are noisy... Are you experiencing the same thing?

Does Accelerated Motion sell new or re-ground cams? Same base circle as stock? I bought a custom ground COMP cam and paid dearly for it. I found it seemed nobody could get cores for roller cams. I don't trust re-grinds of the stockers because I've seen the stock cams show some wear/damage on the lobes.

I used the late-model starter too. WAYYYY better, and they even sound better cranking.

Looks like you used the off-the-shelf Chevy TBI PCV tube to run across the air cleaner housing... neat.

I keep running mine accidentally to 5600, so I empathize with the over-revving by accident.

What did you use to reinforce the bottom end?

I'm interested in the part #'s for the valve train. I rebuilt my '84 Duke using a Comp Cam and SpeedPro pistons. The lighter pistons took 1 pound of weight off of the rotating assembly. '88 crankshaft. I also used rods from a Pontiac 301 Turbo which I balanced. I'm very happy with the engine except for the valve chatter. I deleted the intake baffle and converter. Off idle is a little weak but then the engine comes into it's powerband and pulls very well.

quote Originally posted by Ventura: I'm interested in the part #'s for the valve train. I rebuilt my '84 Duke using a Comp Cam and SpeedPro pistons. The lighter pistons took 1 pound of weight off of the rotating assembly. '88 crankshaft. I also used rods from a Pontiac 301 Turbo which I balanced. I'm very happy with the engine except for the valve chatter. I deleted the intake baffle and converter. Off idle is a little weak but then the engine comes into it's powerband and pulls very well.

There are probably a couple other ways to do what I did, but here's why I went about it this way:
The way I use my car, it's pretty important that it look stock. That's why I have a stock valve cover, air cleaner, EGR, etc on it. It's also why I made these parts choices... bolt-on and stock appearance when you pull the oil fill cap

I used 134-7201 ARP conversion rocker studs. You'll only need a half set, 16 come in the package. These rockers screw down to the stock head, through the stock pushrod guideplate, and convert you over to a pretty standard 3/8-24 rocker stud thread so you can buy common aftermarket parts.

Along with those studs I used Trick Flow rocker nuts (PN# TFS-70000903-8). You can buy 16 if you want, but this part number will get you 8, which is all you need.

The rockers I used are COMP Cams 1261 series non-roller rockers They are one of not many options you have if you want to stay 1.75 ratio with a 3/8" stud. If you order COMP Cams 1261-8 it will get you the 8 you need, but you'll probably have to wait a couple weeks. More commonly COMP Cams 1261-12 (a box of 12) is stocked by the parts houses. It costs a couple more bucks, but you'll have spares and they'll ship same-day.
The nuts that come with the rockers should not be used as they (by design) will tear up the threads of the stud.

If you must have roller rockers, there's some options from Crower and a few others.
(Jeg's Part numbers, but can be purchased other places)
258-73625-8
258-73629-12

I used Dodge 383 pushrods, but this will vary for you since you have non-roller lifters and not-necessarily the same installed height for your valves, head and block deck machining, etc.

One other thing. The combo of parts listed above nearly makes contact with the stock valve cover, so I did this for extra insurance:

Very good info......Thank you!

NICE, and you are in GA too... I hope to see that car sometime! Any tally on the total cost of the changes you made?

So the S10 head was not a direct bolt on as the article suggested? That is interesting as the author of the article said his bolted up. I wonder if the are different heads for the S10? What is everyone doing for a stronger crank? None of the crank manufactures make a better crank for the 2.5?
Top Hat you mentioned your car is an 88. Did you get rid of the balance shafts when you rebuilt your engine?

[This message has been edited by solotwo (edited 10-21-2011).]

What starter did you use?

The starter is a late 90's - early 00's Grand Am starter (as well as several other GM cars).

Starter...
see my cave, starter in general engine section for link.

------------------
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(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Is the cam ground for more torque? Seeing as this engine is limited on engine RPM's more torque at lower rpms would be great.

The cam seems to be a good balance between RPM's and torque. Before the rebuild, the engine seemed to start running out of air at 4500 RPM. Now I've had it up to 5000 RPM, and it seemed to be doing fine. But it also cruises well at 2000-3000 RPM in 5th gear, and launches well (for a duke).
I didn't specify the cam -- I just got what Accelerated Motion recommended.

Nice thread!

KurtAKX... do you have a thread for your 4 cyl build?

quote Originally posted by TopNotch: The cam seems to be a good balance between RPM's and torque. Before the rebuild, the engine seemed to start running out of air at 4500 RPM. Now I've had it up to 5000 RPM, and it seemed to be doing fine. But it also cruises well at 2000-3000 RPM in 5th gear, and launches well (for a duke). I didn't specify the cam -- I just got what Accelerated Motion recommended.

Wouldn't it be great if a crank manufacturing company would forge a stronger harder crankshaft for the 2.5? Not being to familiar with the 2.5 block, wonder if it can be stroked for added torque?

The 88 crank is a little stronger than previous years. And the 88 rods are stronger, too.
The marine engine crank is quite a bit stronger, and perhaps can be used. There was a thread about that, but I don't know if it was ever finished.
I've heard that if you stroke the duke too much, the pistons will pull out of the bores at the bottom of the stroke, because the bores aren't as long as on the marine or SD4 engines.

Ok so much for that idea. Isnt the marine engine a 3 liter? If so can the crank be used in a 2.5?

I've heard that there was a 2.7 and a 3.0 marine engine. And that the 2.7 crank can be used in a duke.

Have you had a chance to drive it enough to get an indication of what mileage is like with this engine?

Daily go-to-work mileage is the same as before the rebuild. Let's just say that my daily driving wouldn't get me a better rate with Progressive's driving monitor (I don't drive to save gas). I haven't done a long trip mileage calculation yet.

That's good to know. If the mileage hasnt changed, then the mods to make it go faster hasn't taken away from the fuel efficiency.