quote Originally posted by 30+mpg: "Quieting a Duke Engine" They all have the "diesel" clatter. Learn to live with it. Dynomat the interior firewall and put some insulation back on the engine side of the firewall. That way, you won't mess up your Duke by trying to out engineer the engine designers (engineers).

Ah phoey I say live a little and use your brain and trust yourself!

I think Bob Dylan said something like.....Aint gonna work for Maggies Pa no more, He puts his cigar out in your face for fun and has bars on all his windows and the National Guard at the front and back door to be safe. We'll I aint working for Maggie's Pa, heck I hear he's a Scrooge anyway.

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84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White

ok my 86 for some reason decided to correct it's self. could be the marvel mystery oil i put in because i'm getting an oil change soon and wanted to clean things out. But there is my friends 84 that i would like to try this on. Thanks guys.

I too tried Mystery oil and other thickened oils. They worked for up to a week for me and then things went back. The shims had the same noise effect but took a few hours and then lasted. I guess it takes a little settling time. I remember leaving one out and coming back to it a few weeks later I could hear the noise with a stethoscope and tell it came from the rocker I did not treat. But just like the thick oils it quiets rocker noise but doesn't make it anything like a modern super quiet engine, the kind you may not be sure is off or on etc...

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84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White

quote White 84 SE: Ah phoey I say live a little and use your brain and trust yourself! I think Bob Dylan said something like.....Aint gonna work for Maggies Pa no more, He puts his cigar out in your face for fun and has bars on all his windows and the National Guard at the front and back door to be safe. We'll I aint working for Maggie's Pa, heck I hear he's a Scrooge anyway.

Experience is the BEST teacher. My Black 2M4 is running on its 5th Duke. What is yours on?

quote Originally posted by 30+mpg: Experience is the BEST teacher. My Black 2M4 is running on its 5th Duke. What is yours on?

5th!

What are you doing to them!?!

I have blown up a few, between several cars. I snapped a crank in one just behind the number 1 main bearing (abuse), tossed a rod through the block on an 87 (previously neglected), popped a hole in a piston on an 84 (no EGR+too much timing+carbon buildup+TORCO fuel), etc.

The one in my red beater car is still in one piece, and its built out of trash-picked parts; it was originally intended as a temporary motor, just to get the car mobile so I wouldn't have to push it around while getting the real engine ready for it. It's got Darkhorizon's 1988 crankshaft in it, its got an 84 head on an 86 block, mixed and matched tin and parts from all different sources, and most of the engine parts came from an engine with a spun bearing that member Cheeze was throwing away.

My "junk" engine has been dynoed up to 5500, drag raced, rallied, autocrossed, rallycrossed, ice raced, and generally been abused severely for the last 25k+ miles. It has probably spent over 50% of its life at WOT. Members of the Detroit Region (or SVR region) SCCA, Scott, or anyone else who's ever ridden in it can attest to this fact.

Not trying to sound harsh, but even if experience is the best teacher, perhaps its lessons are falling on deaf ears if you didn't learn from the first 4 dead engines.

got an update on this. Heard from a friend who was going to try this shim idea on his 84 today. ended up just torquing them down like the book says while using the distributer as the timing mark. said it runs like it's ten years younger. quieter then he's ever had it. can't figure out why since they were torqued down after his head gasket was done 9 not by the book). strange but true. shouldn't make a difference but does.

Yeah, I can loosen all mine up, turn the pivot balls 90 degrees to the existing wear pattern and get mine quieter, too.

That doesn't mean a ludicrous sequence NOT recommended in the factory manual is the reason for the improvement.

i Meant that they are hydraulic lifters so it shouldn't matter what sequence or where the valves are but it might actually matter.

quote Originally posted by Finally_Mine_86_GT: i Meant that they are hydraulic lifters so it shouldn't matter what sequence or where the valves are but it might actually matter.

It appears you still don't quite get it.

It's not the fact that they're hydraulic lifters that makes a "sequence" of tightening unnecessary, it's the fact that there is no adjustment to be made with the valve lash on a duke. The rocker bolts are simply tightened down until they don't turn anymore (up to a certain torque reading), whereas on a 2.8 there is most certainly an adjustment to be made when the rocker nuts are tightened (and therefore the position of the camshaft is critical). Both engines use hydraulic lifters.

quote KurtAKX: 5th!...

Read https://www.fiero.nl/forum/Forum1/HTML/073843.html

quote Originally posted by 30+mpg: Experience is the BEST teacher. My Black 2M4 is running on its 5th Duke. What is yours on?

This is the only Duke that has ever been in this car. Well if you count the engine recall it is the 2nd Duke that has been in this Fiero. The 1st was one of the burn up jobs back in 1985.

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84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White

quote Originally posted by White 84 SE: The little shim helps keep a little firmer tension

Yes, but too much shim is bad too... bottom out the lifters when cam lobe is at top. Lifters have a sweet spot of compression to work in.
1-2 thousands should be enough. Just enough shim to take up slack in lifters.

Remember… using the shim on the bolt affects the fulcrum on the lever/rocker. whatever shim you use, you tighten the lifter more by the rocker ratio. example: 1 thousands shim = 1.5-1.6 thousands at the lifters. (I forget what the ratio is on OE rockers.)

All,
Post your shim source, and part number, if possible.

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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.
(Jurassic Park)

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

[This message has been edited by theogre (edited 02-21-2011).]

I have never heard so much conversation about a simple issue. All non-adjustable rocker systems have a very specific valve stem height. That dimension puts the plunger in the lifter at the correct location. When a valve is left open when the engine is stopped, The valve spring pressure pushes the oil out of that lifter. The light spring under the plunger in the lifter keeps the rocker from rattling until oil pressure comes up on next startup. If the rockers are noisy, but not worn, the valve stem height is not right.

quote Originally posted by 30+mpg: Experience is the BEST teacher. My Black 2M4 is running on its 5th Duke. What is yours on?

My second 2M4 is running with the engine from my first 2M4 which I rebuilt many years ago. The engine that was in my second 2M4 was roached when someone forgot to keep oil in it. My rebuilt has over 300K miles on it, and I just replaced the original cam gear as it lost a couple of teeth due to age.

I have not done this to my new to me 84 indy.. but my last iron duke powered car I did these things to it to make it quite..
it was an 1980 sunbird hatch back

valve cover/ timing cover/lifter cover.. take to anyplace that installs(sprays) quality pick up truck bed liner, have the outside sprayed.. I also had the air cleaner housing and lid done..
with a pushrod lenth tester tool you can find the correct lenth you need and then call comp cams (and others) and have the correct lenth pushrods made..
if the engines ever had any work done, new head gasket, valve job/ milled head the pushrods are incorrect lenth..
when and if I rebuild a 2.5 for my fiero I'll research adjustable valvetrain.. tey make it for pontiac v8's so it shouldn't be to hard to source parts for this..
also coating the oil pan with bed liner will help tons.. but might not be an option for most..
check your oil for zinc.. these engines need it.. syn oil DOES NOT HAVE ENOUGH ZINC in it.. not all racing oils do either.. and big rig oil lost it in 2010..
and yes the tbi injetor is loud.. can't do much there..

Epic thread resurrection, Mr. Mimbs...

quote Originally posted by carbon: Epic thread resurrection, Mr. Mimbs...

old threads sometime give the answers you need.. sometime they do only after bringing them back from the DEAD..
I'm learning tons from old threads. as I'm a newb here and to fiero's in general...
but if I knew they where this much fun to drive... I'd have bought one a long time ago..

I have a 88 w/ 76 K on it and boy is it noisy, so this is of interist to me? first off let me say this is my first Fiero and my first Duke. I have always liked the looks of the GT but I found this notch back for cheep so thats what I bought . I am an expereanced engine builder and a avid pontiac fan . be i have been resurching this little car and motor for a while now . and I can say it drives like it is on rails.(195/ 55/ 15 Komo's) the lifters are the same as all other roller cam GMs of the same era . and there not noisy? If you would like to learn about proper lifter preload I would sugest down loading the Crane Cams catalog and in the back there is a section on adjusting the valve train these guys are experts on this. I am a gear head and the first place you look to improve an engines performance is in the intake and exhaust this is where you can get the most improvement with this engin i beileve. and to my suprise no one offers a tuned exhaust for the Duke in the fiero. i bought a header for 81-83 jeep with the duke motor and reworked it to fit around the starter, removed the stock Cat and hooked it up to the stock exh. WOW What a change it made not only in performance but it sounds good like a sport coup should.. there are some intake manifolds available but they wont fit all heads some slight changes from year to year. I found the head on 91-92 lumana has better exh. and intake ports. I am in process of setting up 91 head, ported with bigger valves, stiffer springs, and roller rockers. should be worth a few ponies !! you have to use the intake that matches the head if you want it to be a bolt on. I would like to post some pics but unable to right now, but soon I hope, and thanks to everones imput on this noisy thing.
Best regards