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Boozebag
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Discussion Starter #1
Here is a list of some parts and improvements that would make a noticeable difference for a Duke rebuild:
Start at the bottom...
1. Clevite 77 tri metal bearings
2. Balanced reciprocating assembly (important!)
3. High volume oil pump (some will argue this, but it has worked for me every time)
4. High end FelPro gasket set. Has the silicone blue oil pan gasket.
5. Chevy 350 flat top pistons. They have the same compression height as the stock dish 2.5 piston (pin to piston crown distance) and the same size piston pin too. You can buy a hypereutectic 350 piston for $16!!! Compression will increase from 8.5 to a little over 9:1.
6. Moly piston rings. Better than the iron ductile units.
7. Match port the head to gaskets. The heads on these engines are pretty close, but the benefit is there still...
8. Porting the intake/ exhaust runners. This can be tricky, you can actually lose HPs. If you knock off the valve guide sharp edges and blend the guide in the bowl, this usually helps flow and doesn't mess up the runners.
9. Cam. Oregon Cam grinders have several different grinds for this engine. They are great... you can actually talk to these guys and tell them what your requirements are, they will provide you with the right cam for your application.
10. Aluminum timing gear. This replaces the phenolic gear and doesn't shred. They are slightly noisier than the stock gear, but the long life is by far a better choice
11. Roller rockers. IIRC, Chevy big block rockers are a bolt on. There are different ratios, the Oregon boys are the best for recommending ratio choice/ cam combination.
12. Stock header... This is an easy one. Cut the stock header flange off,
(it's 1 1/2" in diameter) and weld on a 2 1/2" flange. This will effectively give you a performance header for cheap.
13. 2 1/2" exhaust - a muff shop can bend up a head pipe to cat for a 2 1/2" pipe.
14. High flow 2 1/2" cat. This connects right to the pipe from the header.
15. Performance exhaust: http://www.summitracing.com/parts/sum-680031
16. If you are really going for it... a performance chip for the ECU.

These inprovements can give you an honest 120 HPs. Not much of a gain, but it makes an S10 Duke fun to drive.

Figure about $1,500 to $1,800 for everything - if you do most of the work yourself. It can be done for less if you shop around and don't go for all of the upgrades.
 

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Boozebag
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9,041 Posts
Discussion Starter #2
Some pics of parts:

Hypereutectic 350 pistons and fresh Clevite bearings:


Aluminum cam gear:


Fresh flat top 350 pistons installed in the 2.5 block


Another pic of the 350 piston:


Fresh high volume oil pump:


Here's a pic of a Pontiac 301 V8 piston. They also fit the 2.5. The 350 pistons are a better choice.


Here's a pic of the crappy crank in a 2.5. No counterweights, and made out of paper. This is why balancing is so important. The factory does a crap job balancing these POSs.


I'll post more if there is any interest.
 

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Cool, Tight, & STRONG....
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1,942 Posts
MM---

I am on with this thread!...:cool:...

I have some suggestions (doesn't everyone?) namely:

The use of a cooler running t-stat.

"Run at full ECU timing advance, 100% of the run time.."

The 180* F. t-stat is OK for use here. AC-Delco calls the 180* t-stat an "Alternate" range, which is like having a papal blessing, IMO.

There is so much more...:)...
 

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Cool, Tight, & STRONG....
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MM--

Actually, the pic that you posted of your crankshaft, is the "best of the bad" OE crankshafts...

It has the large, gear on it, the one that the engineers at Pontiac put on the crank to drive the oil pump.

It acts like a extra weight on the crank to stabilize the whole thing, esp. at the high end of the rpm range.

If you have an Iron Duke that has the early non-gear crankshaft in it, and would like to do a mod that will truly help, I believe this later model will swap into your early motor..?..
 

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Here's a pic of the crappy crank in a 2.5. No counterweights, and made out of paper. This is why balancing is so important. The factory does a crap job balancing these POSs.


I'll post more if there is any interest.
are we under the assumption the crank and flywheel are inherently balanced?
 

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Cool, Tight, & STRONG....
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nighthawk--

One can never fully "ass"ume anything with these motors, because just when you believe you have them figured out, they will jump up and jab you in the back.

The real problem with the OE cranks is the factory specs on the balancing tolerances. They are much too loose/wide for stability. They are fine for all other uses, such as low RPMs and less than stellar performance.

The use of a harmonic balancer on the front snout of the engine crankshaft is also highly recommended.

Cast OE cranks do flex a bit more than a fully counter-weighted forged unit, but then a "Scat" crank costs big bucks..:eek:..
 

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Cool, Tight, & STRONG....
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Here is a link for you all, one that clearly shows most everything:

Iron Duke Performance FAQ: « My Fiero @ OceanMoon.com

In it you will find the machine shop balance spec listed at
+5 grams..?..I don't know if that is correct, remembering that my (sand car) 2110cc VW motor was built using a "plus or minus" gram scale..ie. x grams + or -...

??
 

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nighthawk--

One can never fully "ass"ume anything with these motors, because just when you believe you have them figured out, they will jump up and jab you in the back.

The real problem with the OE cranks is the factory specs on the balancing tolerances. They are much too loose/wide for stability. They are fine for all other uses, such as low RPMs and less than stellar performance.

The use of a harmonic balancer on the front snout of the engine crankshaft is also highly recommended.

Cast OE cranks do flex a bit more than a fully counter-weighted forged unit, but then a "Scat" crank costs big bucks..:eek:..
how big do those bucks get
 

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Boozebag
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Discussion Starter #11
Everything in this thread is welcome!! The reason for it is to help out anyone wanting a little more bag from their Duke or rebuilding with better than original parts.

SE - thanks for the input. There is always something I forget. :D

I'll post more pics too.
 

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Boozebag
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Discussion Starter #12
Here are some pics of the "header" mod. The factory exhaust manifold really isn't that bad. The only real problem is the restriction at the end of the assembly.
First:
Cut the end flange close to the collector - A Sawzall works really well for this action:


The flange end reduces an incredible amount... Here's the culprit:


Whiskey Tango Foxtrot Dood!!!! The actual header is 2 1/2" - the flange exit is 1 1/2"!!!


Pic of a 2 1/2" flange I cut off of a ricer system. These flanges are avalable at most parts supermarkets...


Make sure that you align the flange so it doesn't hit any part of the engine/steeringcolumn/firewall.


Welded on:


Finished:


The next step is to add a 2 1/2" exhaust behind this. You can tie this mod into your current exhaust fairly easily - if you don't have time or money for the rest.

More pics of the exhaust soon.
 

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Boozebag
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Discussion Starter #13
Here's the exhaust that will help the engine really breathe...
I installed a very expensive Clifford research header... a quick pic of it:


I had a muff shop bend up a cross over head pipe that is 2 1/2", it empties into a 2 1/2" high flow cat.


This is another mod I had to do, you won't need to do this since the O2 sensor is built into the factory header:


From the cat, the pipe is still 2 1/2" and goes to a 3" muff.


Here is the transition:


And lastly, to a 3" taipipe...


The entire system fits exactly like a factory GM exhaust. It hangs by the same brackets/hangers and looks totally stock.. . It's available from Summit, the link is above in the first post. This does not sound anything like Rice, it has a much deeper sound and doesn't really resonate in the cab.
I didn't get to the tuning part of the build, the engine runs super lean, and would probably gain a ton of power with a better fuel and ignition map. Maybe some day... I'll have to drive the truck back to Baton Rouge
since it currently is asleep in one of my barns.
Anyway. hope this helps out...

Confucius say: Man with big pipe make good power... :haha:
 

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Cool, Tight, & STRONG....
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MM---

Thank you for the nice words..:)...

For those brand new to the Iron Duke, don't spend a ton of money in the vain attempt to rebuild another VIN series OTHER than a Code E or A Code S-10 block.

The E and A Code were cast differently from all of the other year code blocks.
 

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Boozebag
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9,041 Posts
Discussion Starter #15
Thanks again SE... I should also have mentioned that.:)
 

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Boozebag
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9,041 Posts
Discussion Starter #17
MM
let me know when you put that puppy up for sale...?
it is a turkish green "ranger-beater" for sure!
peace out
My GF named it the "Barbie" truck. It is teal green or turquoise. It has been an excellent truck. I don't drive it as much as I used to, it sits in one of my barns... I drive it a few times each year.
Maybe I should sell it. I have way too many vehicles.
 

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Boozebag
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9,041 Posts
Discussion Starter #19
yep & i want my next duke/dime stick and reg. cab/bed, & as little rust as possible. lol.
I have 8 of these tugs. Only one has rust on it.
 

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Cool, Tight, & STRONG....
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1,942 Posts
MM---

Thank you for the nice words..:)...

For those brand new to the Iron Duke, don't spend a ton of money in the vain attempt to rebuild another VIN series OTHER than a Code E or A Code S-10 block.

The E and A Code were cast differently from all of the other year code blocks.
====

The E Code and the A Code had "solid wall" webbing cast into them (between the cylinders)
..they are the most desirous of all non-race block Duke motors. They were commonly called "Roller Blocks", because of the roller hydraulic lifters that they all had. Also, they were stock in the Postal Van (LLV).

As an aside here:

The hydro lifters are a good thing/bad thing, IMHO.

Bad thing because you are limited to the lift that you can/could use. And they will not follow a "radical" ground camshaft profile, either. Lifter floating raises it's ugly head. But the good is that the cylinder head flow gives up at about 4500 RPM so this is all moot.

Also, the hydro lifters need clean oil and LOTS of it to work well. This is why I always have said that you do not need a fancy oil pump on these engines. Your money is better spent elsewhere. I have read before that an aftermarket, Hi-Pressure oil pump takes 4 to 6 HP to run it. I have no facts to back that up, however...:cool:
 
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