quote Originally posted by Patrick: Am I missing something here? Why is there even a problem with "lash" on an engine with hydraulic lifters? I'd have to think that if the hydraulic lifters (assuming that they are in decent shape) can't make up for a bit of wear in the valve train, then the whole engine must be a real mess.

No way dude! I just rebuilt the whole thing. Just want it as smooth and quiet as possible even if I were to do something unconventional. You dont have any suggestions?

quote Originally posted by White 84 SE: I just rebuilt the whole thing. Just want it as smooth and quiet as possible even if I were to do something unconventional. You dont have any suggestions?

My suggestion was to allow the hydraulic lifters to do their job , and that job is to eliminate any free play in the valve train (as long as the lifters themselves have been set up properly).

cool... (Dontya be dissin ma Duke..laughs) I didnt realize the lifters take up slack. I thought they just pump up oil. Seems like there is just inherent noise...... lead flashing used for noise barrier may work.

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

[This message has been edited by White 84 SE (edited 10-01-2009).]

quote Originally posted by White 84 SE: I didnt realize the lifters take up slack. I thought they just pump up oil.

You have much to learn, grasshopper.

quote Originally posted by White 84 SE: Hold up here!.... The rocker pivots on the ball. Shimming can only raise the rockers. What you guys talking about? I dont quite understand. It's hurting my brain!!!

Like this...

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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 of every forum page...)

quote Originally posted by theogre:

Isn't it a nut on top of the pivot ball?

quote Originally posted by theogre: Like this...

Woah! It's like THAT? Oh maaaan! Well that solves that!! Thanks a TON Ogre!!!

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

quote Originally posted by White 84 SE: Patrick....no I think Ogre's got it right come to think of it. Man, I dissassembled and cleaned it but somehow I forgot the structure of it.... Musta been tired....

If it's anything like a V8 Chevy, it's a stud with a nut on the top.

quote Originally posted by Patrick: Isn't it a nut on top of the pivot ball?

No. Bolt.

Nut on Fiero V6. V6 don't need shim washer.

quote Originally posted by White 84 SE: Woah! It's like THAT? Oh maaaan! Well that solves that!! Thanks a TON Ogre!!!

Picture...

quote Originally posted by Patrick:[/B[QUOTE][B]Originally posted by Patrick: Am I missing something here? Why is there even a problem with "lash" on an engine with hydraulic lifters?

Too loose from GM. Bean counter cause a problem. Lifter can't take up enough. Especial when car gets old. Shim fix that and it's cheap.

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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 of every forum page...)

Thanks for the clarification, Ogre. I’ve never had the valve cover off a duke. I didn’t realize they were so archaic!

This has got me to thinking - I'm sure this has been suggested before, but couldn't studs be screwed into the duke's block instead of using the bolts, and then use nuts and adjust the lifters the same way as on the V6/Chevy V8.

Yeah, I know shims are cheaper, but theoretically, couldn't studs (and nuts) be used?

[This message has been edited by Patrick (edited 10-01-2009).]

Patrick, yes you can put studs in the duke head. Chevy LS1 LS2 aftermarket rocker arm studs work. Then you can use Harland Sharp Roller tip rocker arms (chevy inline six) . I have not got it all installed yet, but everything looks good. I hope it is quieter and it should pick up a few HP. jm

O.k> just to recap here... To Quiet a Duke: check exhaust for leaks and seal as needed; Spray or better paint on sound deadener where you can; lead shielding on firewall, trunk, inside valve cover and over lifter cover; synthetic oil; tighten up a loose valvetrain by replacement parts or shims; replace perch bolts with studs and a set of roller rockers;

Anything else? perhaps I majorly missed something....

I have a V6 and don't know what a duke valve cover is like...but from pictures it looks like stamped steel.

If it's like a tin can, kind of thin, and easily transmits vibration like a bell, then try coating it with something heavy, and heat resistant.

Pickup truck bedliner in a can might work, and looks okay.

quote Originally posted by pmbrunelle: I have a V6 and don't know what a duke valve cover is like...but from pictures it looks like stamped steel. If it's like a tin can, kind of thin, and easily transmits vibration like a bell,....

Not only the valve cover, but also the lifter cover, oil pan, and block itself.

quote Originally posted by mountainman: Patrick, yes you can put studs in the duke head. Chevy LS1 LS2 aftermarket rocker arm studs work. Then you can use Harland Sharp Roller tip rocker arms (chevy inline six) . I have not got it all installed yet, but everything looks good. I hope it is quieter and it should pick up a few HP.

Hmmm.... interesting. If I keep one of my dukes I may look into doing that. I hope you report on how well it works out for you.

Thanks for the info.

[EDIT] By the way, are those roller tip rockers 1.5 or 1.6? If 1.5, why would you not have tried 1.6? Just curious.

[This message has been edited by Patrick (edited 10-02-2009).]

This idea may be far fetched, but I just woke up and my brain is still jello, but...

What if you could take an engine cover, like a 3800 or aurora 4.0 has, cut a hole the same diameter as the air cleaner cover, somehow mold the air cleaner cover to the engine cover (fiberglass, epoxy, etc..) then bolt the whole thing down over the duke via the air cleaner wing nuts. Perhaps this would help hold some noise in. Any thoughts?

[This message has been edited by Genopsyde (edited 10-02-2009).]

quote Originally posted by Genopsyde: This idea may be far fetched, but I just woke up and my brain is still jello, but... What if you could take an engine cover, like a 3800 or aurora 4.0 has, cut a hole the same diameter as the air cleaner cover, somehow mold the air cleaner cover to the engine cover (fiberglass, epoxy, etc..) then bolt the whole thing down over the duke via the air cleaner wing nuts. Perhaps this would help hold some noise in. Any thoughts?

Go back to bed.

quote Originally posted by Patrick: Thanks for the clarification, Ogre. I’ve never had the valve cover off a duke. I didn’t realize they were so archaic! This has got me to thinking - I'm sure this has been suggested before, but couldn't studs be screwed into the duke's block instead of using the bolts, and then use nuts and adjust the lifters the same way as on the V6/Chevy V8. Yeah, I know shims are cheaper, but theoretically, couldn't studs (and nuts) be used?

Yes.
This for a GM BB V8 with same problem.... Won't fit L4 but same ideal.

The kit don't need pivot ball or rocker replace. Drop in for rocket bolt. (The extra black part fit inside the pivot ball.)
Can make one like kit? no ideal. It can be done but cost more.
If you replace rocker and stud then easier and cost more too.

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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 of every forum page...)

quote Originally posted by Patrick: Go back to bed.

I did..........and it didn't help.

quote Originally posted by Genopsyde: I did..........and it didn't help.

lol...well what do you think of the lead lining idea?

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

Patrick, the rockers are 1.75 stock. jm

quote Originally posted by mountainman: Patrick, the rockers are 1.75 stock.

I guess it's just the 2.8 that's 1.5 stock then.

If 1.75 is stock on the duke (is it really?) then are there higher ratio rockers available to increase lift with the stock cam?

quote Originally posted by White 84 SE: lol...well what do you think of the lead lining idea?

I don't like lead. don't like to handle it. I would just dynamat the whole engine bay

do not use lead ,,the new heat resistant material will work just fine there is an insulation material less expensive called fatmat or something like that..
I would not shim it, unless you are a really experience gear head ,,same with the pushrods ,, they are just idea,s
The insulation can be installed any where you want it ,, even to the underside engine hood cover ,,the air vents will still let the sound out ,,
The problem with insulating the inner valve cover,, the stuff could fall off into the valves
My first Fiero was a GT duke,, very very quiet ,,it had an offenhauser fined valve cover ,,My duke fiero was build by a perfectionist..
You can install a larger finned aluminum valve cover over the one on there now ..it all depends on the amount of work and alteration you are tolerant of..egr,, aircleaner,ect..
I am going to build a GT duke it will have an aluminum Marine duke valve cover (or offenhauser) and an edelbrock elite aircleaner cover ..Now Im thinking seriously about a stock valve cover with another over it Hmmm..

Well, I still think lead is a good idea but perhaps not on the inside of any covers.... Here's an observation: The exhaust manifold and valvetrain are positioned right at ear level and pretty close. And the engine vents are right up to the glass. It will be good to re-fab a cover to replace the rear grill and have the vents be further back. Instead of being directly over the spark plug wires it can be just over the air cleaner case much like the Porsches. An the vents can be made to direct noise outward rather than toward the cabin as the current design does. Also, since the exhaust manifold is right at ear level trading the thin stainless steel type with the thicker cast iron ones from Celebrities and Monzas will contain much of the noise too. Again, if the push rods are slacky the shims will quiet them.

By the way I went and purchased some "shims". The autoparts stores couldnt pull anything up out of the computers for the Duke so I went to Ace Hardware and got the thinnest "machine bushings" I could find that would fit. They are thicker than my gut tells me to use so I wont try them.

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

Patrick, yeah the rockers are 1.75.. the only place I could find for roller rockers is Harland Sharp. They told me the rockers are 1.75. The studs were trial and error. The head takes an 8mm. thread, just so happens so does the LS1. The rocker side of the LS1 stud is 1.5 inches. If there was more spring presure, stud length might be an issue. I get 5 turns on the adjusting nut for a correctly adjusted lifter. With luck this should work ok. jm

quote Originally posted by mountainman: With luck this should work ok.

Make sure you let us know!

Well Kiddies I went ahead and installed the rocker arm shims. Yep, its quieter. pretty smooth. The noise coming from the intake side of the valve cover is seriously reduced. I have a theory about why this worked. It looks like the pushrod guide plates which go in between the rocker bolts and the perches may have been an after thought. This raises the height of rocker arms about 1/32nd". By putting in shims above the rocker arms and ball one may be setting the rockers down 1/32nd" to the original intended design height. Just a thought.....

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

[This message has been edited by White 84 SE (edited 10-04-2009).]

I presume this was an easy install,,that anyone with moderate skills could do?? this is much easier & cheaper than the pushrods..
Now I know about shims,I had been unsure ,,never seen one!!!, thanks forum members ogre & white 84 se

Not bi curious ,,, I am very curious about the Harlan Sharp rockers,,inquiring minds want to know at a date when you have data

[This message has been edited by uhlanstan (edited 10-04-2009).]

quote Originally posted by uhlanstan: I presume this was an easy install,,that anyone with moderate skills could do?? this is much easier & cheaper than the pushrods.. Now I know about shims,I had been unsure ,,never seen one!!!, thanks forum members ogre & white 84 se Not bi curious ,,, I am very curious about the Harlan Sharp rockers,,inquiring minds want to know at a date when you have data

Yea it was too easy to install, and $2 or less!! I had a look at those rockers and noticed they have play side to side. I believe this is what makes the clatter sound. On the underside the wear spot for the valve side is not exactly centered. I imagine that in action they may tend to sort of slide from side to side a bit especially if worn. The result would be a ting every other rev....times 8. New OEM rockers would help but not cure the problem. Roller rockers would help a lot. This is all a guess but the shims did quiet the Duke significantly. Still a few other things to try.

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

where did you get them and what is the shim thickness?

Hello again, got them from ACE Hardware, they are called machine bushings and they were pretty thin...like 1/16".

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

do you remember the inner and outer diameter by chance?

quote Originally posted by White 84 SE: Hello again, got them from ACE Hardware, they are called machine bushings and they were pretty thin...like 1/16".

I'm sorry but I'm just not understanding where you put the shim? could you elaborate a bit? Thanks.

I have no experience with Shims, but I changed my 96 Impala (LT1) to roller rockers. Two different times..using different brands of rockers. I can tell you roller rockers did NOT quiet the engine. If anything they were louder than stock.

As far as where the sound is coming from, in my case...it is not the exhaust. I have no leaks, and I just recently intalled a brand new muffler and Cat (replacing my original which had been hollowed out) and to my disappointment, the noise from my engine was unchanged.

I think next I'll try the idea mentioned above of using a blanket to try to isolate the noise.

"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).

quote Originally posted by TONY_C: I'm sorry but I'm just not understanding where you put the shim? could you elaborate a bit? Thanks.

LOOK ABOVE 32 POSTS Ogre made pictures AND he labeled them.


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

[This message has been edited by White 84 SE (edited 04-05-2010).]