here are all the currently manufactured performance parts for the iron duke(tech4) inline 2.5l 4 cylinder

camshafts;
http://www.amotion.com/p4.html <---only one with roller cams
http://www.compcams.com/DefaultWide.asp
http://www.cranecams.com/
http://www.iskycams.com/
http://schneidercams.com/
http://camcraftcams.com/

pistons
well anything with a .927 pin should work(sorry people you have to do math here)

rockers
http://www.cranecams.com/


hp engine kit(84 only)
http://www.flatlanderracing.com/


carb intakes
http://www.cliffordperformance.net/
offenhauser use to make them too

bolt on stuff
holley and edelbrock used to make intakes, tbi and exhaust headers; check ebay people

[This message has been edited by baldlobo (edited 01-06-2009).]

Isky makes roller cams for the duke. They'll also do custom grinds in 5-bearing SD and regular 3-bearing. I got a solid roller 5 bearing cam with a "custom" grind from them.

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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 its mouth shut and pushed it down a flight of stairs. (Leader of the Insurgency)

Edelbrock/GM 4-bbl manifold GM PN 10038470
$247 http://www.sallee-chevrolet.com


SD4 PONTIAC valve cover (Edelbrock) GM PN 10031327
$161 http://www.gmpartsdirect.com

[This message has been edited by fierosound (edited 05-19-2009).]

i'd really like the thank you guys this makes my build alot easyer. so this is either a free bump or a thanks

quote Originally posted by FastIndyFiero: Isky makes roller cams for the duke. They'll also do custom grinds in 5-bearing SD and regular 3-bearing. I got a solid roller 5 bearing cam with a "custom" grind from them.

Who did you work with at Isky? I talked to Ron (Iskendrian) about this a couple months ago (getting a custom 3 bearing roller cam) and he told me he didn't have any cores to do roller cams, nor did he know where to get them.

He also told me that the induction hardening on my factory cam wasn't deep enough to regrind to the specs I want ( in the neighborhood of 218-224 duration @.050")

quote Originally posted by KurtAKX: Who did you work with at Isky? I talked to Ron (Iskendrian) about this a couple months ago (getting a custom 3 bearing roller cam) and he told me he didn't have any cores to do roller cams, nor did he know where to get them. He also told me that the induction hardening on my factory cam wasn't deep enough to regrind to the specs I want ( in the neighborhood of 218-224 duration @.050")

It's been a couple years so I can't remember who I talked to. I also had issues with the hardening and they ground through it on a couple of their cores before having it hardened just slightly deeper. Were you looking to do a hyd. roller or solid roller? I'll try to find a name.

[This message has been edited by FastIndyFiero (edited 01-06-2009).]

hydraulic roller. let me know what you find, thanks!

to add to this thread, i'd like to add that there are only 2 different forging for connecting rods.

324(which is also used in all variations of the 301 including the turbo version) iron duke 77'-86'(BT=.500)

987 iron duke 87'-94'(BT=.640)

can some one give me a hint as to what BT means in connection with connecting rods?

oh and the difference between the dis and non-dis crank is 4lbs

Its beam thickness. If you had the two rods side by side, you'd see it pretty obviously.

----> link to brief con rod comparison: https://www.fiero.nl/forum/Forum2/HTML/095392.html

[This message has been edited by KurtAKX (edited 01-07-2009).]

for all those who would like performance from the duke; no matter what you do weather it is a cam change, bolt-on.

Everything will need more air/fuel to make more hp and torque.

this link is for modifing the stock tbi to increase air flow(in case you can't find the holley tbi)
http://www.thirdgen.org/ultimatetbi2

for more fuel(the tbi flow rates are down near the bottem of the page)
http://www.rowand.net/Shop/.../SlantSixTBISwap.htm

there is also a modified fuel pressure regulator cup that gm made, that responds to vacume to lower pressure when under vac; but under full throttle it allows whatever pressure it's set at.

there is one company that states that power can be increased with only changing the fuel pressure to 13 psi(it works on the tbi'ed v8's)

Matching parts are tough for the 4-cylinder. There's a few 4-bbl intakes available from different manufacturers, but only a couple of possible carbs.

The smallest Holley is 390cfm for V6's, but with the overhanging float bowls, it won't fit in the engine bay because it will go through the trunk wall. (I found out the expensive way)



Modification similar to what was done on the actual Pace Car would be needed. In this pic, this was done to accomodate the air cleaner, but you can see how tight everything is.



Edelbrock carbs fit fine and just squeeze in next to the trunk wall, but the smallest 4-bbl they have is a 500cfm (for smaller V8's) that is too big for proper flow on a 4-cylinder. (I found out the expensive way)


With the rise of fuel injection, Carter shelved production of their carbs, but a few years back Edelbrock bought the rights. Edelbrock's carbs are a "new" version of the Carter AFB and AVS but as I said their smallest carbs are 500cfm.

But I managed to find a Carter 9400 400cfm carb (sized for 3.8L). This is a closer functional match to my engine. More detail here: https://www.fiero.nl/forum/F...3/HTML/000077-3.html

Here's a comparison of the throttle bores back-to-back (secondaries in middle). The primary bores are the same, but the secondaries are very different.

Carter 1-7/16" 400cfm on Left - Right is 500cfm 1-11/16" Edelbrock


In a couple ot short test drives, the engine feels much better with this carb. I haven't done alot of driving with this yet, or done final carb tuning as I'm still working on a TCC lockup problem, and odd twitchy handling from the suspension that I have to fix to make the car "safe".

There's an Edelbrock 9400 on eBay righ now if anyone is looking for one. They are VERY HARD to find. Usually the MG guys snap them up for their Buick 215 aluminum V8 engine swaps.
http://cgi.ebay.com/ebaymot...dZ1QQsspagenameZWD1V

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3.4L S/C 87 GT www.fierosound.com
2002/2003/2004 World of Wheels Winner &
Multiple IASCA Stereo Award Winner
My SD4 Indy www.fiero.nl/forum/Forum2/HTML/096075.html

[This message has been edited by fierosound (edited 05-19-2009).]