I've hopped my Duke and now I like it but for one thing.... It has inherent noise issues. There have been things the engineers have done to reduce noise and I am checking them out via searches etc. So far I find that Chrysler used rubber seals in places not normally thought about to "keep the engine noise in the engine". This is where silicone will come in handy. The other thing I can think of is that the Duke valve AND lifter covers are made from the thinnest steel possible. I am certain some improvements can be made there as well. Also, the inner body panel surfaces can be shot with undercoating and fiberglass damping. Theres a lot that can be done by the shade tree mechanic it seems like. Im going to be getting on that next.
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
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06:04 PM
PFF
System Bot
TopNotch Member
Posts: 3537 From: Lawrenceville, GA USA Registered: Feb 2009
I put a Super Duty valve cover on my duke (it's thick aluminum), and, while it makes it look cool, it didn't change the noise that much. Some cars have sound deadening stuff in the hood over the engine. On the Fiero, there's just plastic. Maybe you could put something there that would help.
use synthetic oil 10/30 ..10/40,,you can get longer pushrods in small increments but you have to use care ..it is difficult to obtain the tight fit in the lifters and pushrods ,,my 88 was very quiet (for a duke ) but I loaned it to a friend and it was never the same,, Fiero GT guy has it now ..I regret selling it ,,I wanted a red GT with the custom rollercage gerbil in the front spare compartment .. a heavier dyno oil (20/50) will help quiet the engine down actually a good idea in warmer climates usefull also on a high miler duke.. Because of vents it is difficult to quiet with insulation
[This message has been edited by uhlanstan (edited 09-20-2009).]
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10:34 PM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
I put a Super Duty valve cover on my duke (it's thick aluminum), and, while it makes it look cool, it didn't change the noise that much. Some cars have sound deadening stuff in the hood over the engine. On the Fiero, there's just plastic. Maybe you could put something there that would help.
Awesome thanks! I was thinking of making a heavier valve cover from aluminum but as you note it doesnt muffle the valve train noise much. I will do something with the insulation idea though. Thanks!
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10:56 PM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
use synthetic oil 10/30 ..10/40,,you can get longer pushrods in small increments but you have to use care ..it is difficult to obtain the tight fit in the lifters and pushrods ,,my 88 was very quiet (for a duke ) but I loaned it to a friend and it was never the same,, Fiero GT guy has it now ..I regret selling it ,,I wanted a red GT with the custom rollercage gerbil in the front spare compartment .. a heavier dyno oil (20/50) will help quiet the engine down actually a good idea in warmer climates usefull also on a high miler duke.. Because of vents it is difficult to quiet with insulation
Woah! I just switched to synthetic tonight and I chose 10/30 too! Does seem a bit quieter...but it was raining so not 100% sure. About those push rods. I was thinking to maybe file down the rocker perches a little to get a snugger fit. Bad idea? ha ha that's your gerbil! thats funny!! About those vents... I was thinking to fab a new central vent (this is an 84) out of fiberglass and have it styled somewhat after the Solstice with semi circular holes. They would be smaller and fiberglass absorbs more noise where aluminum kinda sharpens it. That way I can have more insulation. Perhaps baffles to collect heat and bounce noise back.
[This message has been edited by White 84 SE (edited 09-21-2009).]
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11:08 PM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
So I was snooping around the engine compartment with a long vacuum tube stuck in my ear...... Seemed like a lot of noise coming from the area under the EGR but in the head. Thats that area where theres an exhaust passage that connects to the EGR to supply exhaust gas when needed. It's also where the center push rods and rockers chat with the rod guides(84 Duke). Most noise came from push rod/lifter side of engine. I checked down below where the lifters are. I can hear that clatter sound but its very faint and contained. There was also a bit of noise I could hear from outside the exhaust manifold...again coming from the center of the head. I am getting the idea that the EGR exhaust passage if plugged with JBWeld may serve to quiet the Duke a good amount. After that tightening up the (lash) between the rockers and push rods may be a plan.
It may be that the mushroom shape of the EGR being in direct contact with the exhaust kinda serves as a sort of noise amplifier. I mean in a way it is actually constructed like a phonagraph complete with a resonating diaphram at the top!! That and the air cleaner case is another vibrating diaphram. Got my work cut out.....
[This message has been edited by White 84 SE (edited 09-21-2009).]
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11:29 PM
Sep 21st, 2009
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
Heavier oil will quiet any engine.. a worn engine benefits from an oil thickener Like STP in many ways keep the stock duke air cleaner
to locate areas that you can quiet ,,just drape a heavy wool or thick cotton blanket over that area for a few seconds the EGR runs right to the combustion chamber you can place thermo insulation under the air cleaner top lid ,,but keep the stock air cleaner
I was going to adapt an edelbrock elite cover in place of the stock duke air cleaner cover ,,but my distain for that particular car ,,put this on hold.. The elite units are expensive ,you buy forjust the cover,,then you have to adapt to the duke,,but a neatojet engine upgrade it will put you one up on the other unwashed peasant duke owners
There use to be a thick material you painted your inner valve covers with to quiet them.. but do not remember seeing it in many years ..check with sites that deal with this sort of thing,,seems like it would end up in the valve train
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04:37 PM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
Heavier oil will quiet any engine.. a worn engine benefits from an oil thickener Like STP in many ways keep the stock duke air cleaner
to locate areas that you can quiet ,,just drape a heavy wool or thick cotton blanket over that area for a few seconds the EGR runs right to the combustion chamber you can place thermo insulation under the air cleaner top lid ,,but keep the stock air cleaner
I was going to adapt an edelbrock elite cover in place of the stock duke air cleaner cover ,,but my distain for that particular car ,,put this on hold.. The elite units are expensive ,you buy forjust the cover,,then you have to adapt to the duke,,but a neatojet engine upgrade it will put you one up on the other unwashed peasant duke owners
There use to be a thick material you painted your inner valve covers with to quiet them.. but do not remember seeing it in many years ..check with sites that deal with this sort of thing,,seems like it would end up in the valve train
Hey thanks Uhly, Would a reconditioned engine be considered worn? Dang the EGR goes right to the explosions...Talk about noisey. I think I will block the EGR and fill the passages with JBWeld. Trying to fab some insulation material....thinking fiberglass between aluminum foil......
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
THE DUKE EGR IS SIMPLE,, KEEP IT,,,,, TRY THE BLANKET TRICK i AM HAVING A MAJOR HEADACHE WITH THE V 6 EGR SYSTEM ,,,DESIGNED FOR MILLIONAIRS ,ELABORATE OVERKILL..,I HATE IT ,,BUT THE DUKE IS OK..THERE ARE PLATES MADETO BLOCK OFF THE EGR. YOU CAN MAKE ONE FROM ROOFING FLASHING OR A HEAVIER MATERIAL,,NO NEED TO J B WELD..
[This message has been edited by uhlanstan (edited 09-21-2009).]
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10:37 PM
TopNotch Member
Posts: 3537 From: Lawrenceville, GA USA Registered: Feb 2009
You know guys....The EGR idea is really dumb. Introduce O2 robbed exhaust air to cool the engine down. Water is a natural biproduct and it can be collected from the exhaust pipe system. Water will cool the engine and intoduce extra O2 and a little hydrogen both of which will add power. I dont know anyone who has developed a system so I will name it EWR...for exhaust water recirculation....You heard it here first. I figure collect it near the tail pipe and run the the copper line back up the exhaust. It will be steam by the time it makes that journey and simply pipe it into an adapter plate fitted over the EGR port. Perhaps a future project.
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
Remember you cannot adjust the lash on a Duke. You set it at (IIRC) 24lbs and you are done. I don't believe it's like the V6. Who knows, that may just be the problem. Is there any other rocker arm options available for the Duke?
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12:55 PM
2.5 Member
Posts: 43235 From: Southern MN Registered: May 2007
Mine got quieter running 2 quarts of valvoline racing oil combined with my usual oil, which is Max life semi synthetic. The extra zinc in the racing oil did it I think. Not completely gone, but better.
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01:51 PM
LitebulbwithaFiero Member
Posts: 3380 From: LaSalle, Michigan Registered: Jun 2008
You know guys....The EGR idea is really dumb. Introduce O2 robbed exhaust air to cool the engine down. Water is a natural biproduct and it can be collected from the exhaust pipe system. Water will cool the engine and intoduce extra O2 and a little hydrogen both of which will add power. I dont know anyone who has developed a system so I will name it EWR...for exhaust water recirculation....You heard it here first. I figure collect it near the tail pipe and run the the copper line back up the exhaust. It will be steam by the time it makes that journey and simply pipe it into an adapter plate fitted over the EGR port. Perhaps a future project.
Its purpose is not to cool down your engine. How does introducing hot exhaust air into an area that usually gets cool intake air going to cool your engine? The purpose of the EGR system is to reduce NOx. The EGR valve only opens when it won't affect your performance. It opens when you are holding a constant speed. It doesn't open during idle or acceleration. No reason to get rid of it. Also you will have to somehow correct your computer because it changes your spark timing while the EGR valve is open.
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03:35 PM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
Remember you cannot adjust the lash on a Duke. You set it at (IIRC) 24lbs and you are done. I don't believe it's like the V6. Who knows, that may just be the problem. Is there any other rocker arm options available for the Duke?
I was thinking to file the rocker perch a little bit to adjust lash. That would do it no?
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
I believe that would do it. That's precise work though. How would you do it?
File a little torque then check for space when assembled the same as if it were putting in shims.. Although I have never done any thing like this before it seems logical enough. On the other hand like Uhlastan suggested..they make push rods in slightly longer sizes. I do like the idea of keeping the rockers, after decades of wear I am sure they got a nice smooth groove there. One of the later improvements GM made to thier pushrod engines was a sort of groove in the rockers to guide the rods and eliminate noise caused by those guide pieces as they clanked against the rods occasionally.
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
[This message has been edited by White 84 SE (edited 09-23-2009).]
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01:18 PM
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
File a little torque then check for space when assembled the same as if it were putting in shims..
Why not just put in shims then? Under the bolt shoulder to space up (increase) lash, or under between the bolt head and pivot ball to space down (decrease) lash. Its a fun experiment, but I suspect you'll find that it won't decrease noise.
As long as the valvetrain is set up so that the hydraulic lifter's plunger is somewhat compressed, that's all the more "lash" you can take out of it.
If you had the head or block deck surface milled during the rebuild, you've already done something to decrease lash.
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01:27 PM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
Why not just put in shims then? Under the bolt shoulder to space up (increase) lash, or under between the bolt head and pivot ball to space down (decrease) lash. Its a fun experiment, but I suspect you'll find that it won't decrease noise.
As long as the valvetrain is set up so that the hydraulic lifter's plunger is somewhat compressed, that's all the more "lash" you can take out of it.
If you had the head or block deck surface milled during the rebuild, you've already done something to decrease lash.
Well Kurt I dont see shimming under the bolthead will actually lower rocker any. I didnt have the head planed. It checked out decent without. But yea that would do it. It would be easy and well...free to file away at it a bit. Just gotta be careful. It can be possible to have stuck open valves. This may even give a little umph. I did say a little right? I mean if it has any lash then the valves arent opening as much as they can. Am I thinking right on this?
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
[This message has been edited by White 84 SE (edited 09-23-2009).]
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01:33 PM
PFF
System Bot
LitebulbwithaFiero Member
Posts: 3380 From: LaSalle, Michigan Registered: Jun 2008
Take the cam lift and rocker ratio and figure out what your valve lift should be. Then measure your valve lift and see if you even have a problem before trying to correct one.
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03:34 PM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
Take the cam lift and rocker ratio and figure out what your valve lift should be. Then measure your valve lift and see if you even have a problem before trying to correct one.
Thanks, your concerns are definitely noted. Appreciated.
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
NO,NO ,NO DID I SAY NO !! ROLLER ROCKERS ARE NOT CHEAP BUT THIS WILL QUIET THE ENGINE..THE DUKE SHOULD HAVE SLIGHTLY LONGER PUSH RODS to take up slack,,TO BRING LESS NOISE.. I BELEAVE YOU USE BIG BLOCK CHEVY PUSH RODS( CORRECT ME HERE ) YOU JUST USE THE NEXT LONGEST PUSH ROD than your present one ,, this is serious gear head stuff BUT THIS IS THE WAY YOU TAKE UP SLACK IN THE VALVE TRAIN,,YEARS AGO THERE WOULD HAVE BEEN FIERO PUSH RODS OO5 ,,O10 LONGER IF A MACHINE SHOP DEEP CUT THE VALVES ON A VALVE JOB YOU NEED SHORTER OR FILE DOWN
the 88 duke is quieter than the early models.in my limited experience,, do not know why ..not so quiet after I loan the car to a friend ,,I needed a place to keep it .. GT guy may still have this car,, it was still much quieter than the average duke after my friend finished with it,, eerrrrrrr!
Originally posted by White 84 SE: The EGR idea is really dumb. Introduce O2 robbed exhaust air to cool the engine down.
O2 robbed. It's inert gas, just along for the ride in the combustion chamber, taking space that would have been otherwise taken by an air/fuel mixture, which does release energy when burned. That's how EGT is reduced.
quote
Originally posted by White 84 SE: I dont know anyone who has developed a system so I will name it EWR...for exhaust water recirculation....You heard it here first. I figure collect it near the tail pipe and run the the copper line back up the exhaust. It will be steam by the time it makes that journey and simply pipe it into an adapter plate fitted over the EGR port.Water will cool the engine and introduce extra O2 and a little hydrogen both of which will add power.
Water like that can only cool the engine in the same way regular EGR does. You are going to find absolutely ZERO diatomic oxygen or hydrogen in the exhaust. Might as well use regular exhaust gas, unless it's the soot you find objectionable.
If you plan on splitting the water molecule into its components, remember energy cannot be created or destroyed...
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04:28 PM
Sep 26th, 2009
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
Righto, But there is inherent energy in stuff. No that project is not big on my list. Besides it's not really about making the Duke engine run quieter really. Any ideas to quiet the Duke. You seem well suited for this sort of investigation.. ------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
[This message has been edited by White 84 SE (edited 09-26-2009).]
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03:56 PM
Sep 27th, 2009
edfiero Member
Posts: 965 From: Coatesville, PA Registered: Nov 2004
NO,NO ,NO DID I SAY NO !! ROLLER ROCKERS ARE NOT CHEAP BUT THIS WILL QUIET THE ENGINE..THE DUKE SHOULD HAVE SLIGHTLY LONGER PUSH RODS to take up slack,,TO BRING LESS NOISE.. I BELEAVE YOU USE BIG BLOCK CHEVY PUSH RODS( CORRECT ME HERE ) YOU JUST USE THE NEXT LONGEST PUSH ROD than your present one ,, this is serious gear head stuff BUT THIS IS THE WAY YOU TAKE UP SLACK IN THE VALVE TRAIN,,YEARS AGO THERE WOULD HAVE BEEN FIERO PUSH RODS OO5 ,,O10 LONGER IF A MACHINE SHOP DEEP CUT THE VALVES ON A VALVE JOB YOU NEED SHORTER OR FILE DOWN
the 88 duke is quieter than the early models.in my limited experience,, do not know why ..not so quiet after I loan the car to a friend ,,I needed a place to keep it .. GT guy may still have this car,, it was still much quieter than the average duke after my friend finished with it,, eerrrrrrr!
Alright Uhls, yea I will go for your Idea and just get the next size up. Thanks your right. BUT STOP YELLING!!!! LOL just joking. But I will get the next longer push rods.
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12:57 AM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
I've heard others say that a fuel heater really didnt do anything when they tried it except maybe made the engine a little quieter and smoother. I have no idea if or why this would or would not work but I installed one tonight of my own invention. I wanted to use it to help better vaporize the gasoline. It gets nice and hot but it doesnt seem to actually warm the gas much. A little yes. Brings it up to luke warm from rather cool. Actually it does seem to run smoother and a little quieter. Not 100% on it but I will get back to ya'll in a couple days about it. I must tell you...I feel a little nervous driving around with it.....
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01:06 AM
PFF
System Bot
Sep 30th, 2009
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
Today I took the Duke to pickup a supercharger. The owner lived an hour west so I got to check out the Duke with the fuel warmer. I gotta say yep, it is smoother and quieter with summer temp gasoline. It was quite tolerable and not at all annoying. Seems like the things tried here and above really have worked thus far. Gonna get those taller pushrods soon. Also going to install insulation and sound deadener spray and that should suffice. Way cool!
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
I dont have anything to contribute to this thread but i do have a question. I have only been in a duke once and it had an exaust system so it was pretty loud either way. I have herd the words it sounds like a sewing machine in the back but is the duke really that loud?
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01:57 AM
Patrick Member
Posts: 37633 From: Vancouver, British Columbia, Canada Registered: Apr 99
Another source of noise on a duke that I don't believe anyone has mentioned, from This thread...
quote
Originally posted by Patrick:
To track down the "screaming" that turned out to be a dent in the timing cover rubbing the timing gear, I used a mechanic's stethosope. Just for fun I tried placing the metal bar of the stethoscope all over the engine to hear different sounds.
When I placed it on the intake manifold I could hear a loud rapid tick ticking sound. It's a sound that I identify with every duke I've ever heard running. I continued to place the metal rod all around the engine until I finally narrowed down what the heck was making that sound. It was the gol' darn injector in the throttle body. My gawd that sucker is noisy!
Have you guys noticed this as well? Why is that one injector in the duke noiser than all six in the 2.8L? Must be because of where it's located, eh?
I bought my Fiero off my uncle who is a mechanic. Before buying it he hooked it up to his diagnostics and fixed/replaced all the sensors that were bad. I changed the spark plugs but not the wires. I changed the oil (non synthetic), could not afford synthetic at the time. Now when the car is at normal temp and idles it sounds like it turned off (from inside the vehicle), thats how quiet it is.
But i have a very low milage duke, so that may play a large part in it. Timing used to be off in this car untill my uncle analyzed the codes with his diagnostics.
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02:48 AM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
Another source of noise on a duke that I don't believe anyone has mentioned, from This thread...
Have you guys noticed this as well? Why is that one injector in the duke noiser than all six in the 2.8L? Must be because of where it's located, eh?
Yea that injecter is nutty. I have a possible solution.... a lead cup deflector attached to the inside top of the air case. I find the sound resonates most from the sides and see no reason why this couldnt be lead coated. So where to get lead sheet and try it out?
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
Why not just put in shims then? Under the bolt shoulder to space up (increase) lash, or under between the bolt head and pivot ball to space down (decrease) lash. Its a fun experiment, but I suspect you'll find that it won't decrease noise.
As long as the valvetrain is set up so that the hydraulic lifter's plunger is somewhat compressed, that's all the more "lash" you can take out of it.
If you had the head or block deck surface milled during the rebuild, you've already done something to decrease lash.
Bing x 3... Shims washer do exist for that reason. NAPA or other auto part should order it. Problem tho pivot ball doesn't all take amount of shim. At lest Intake and exhaust both need different shim or no shim on one. Be very careful mess with shim or you could burn valve. Valve job ain't cheap.
------------------ 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)
Bing x 3... Shims washer do exist for that reason. NAPA or other auto part should order it. Problem tho pivot ball doesn't all take amount of shim. At lest Intake and exhaust both need different shim or no shim on one. Be very careful mess with shim or you could burn valve. Valve job ain't cheap.
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!!!
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07:29 PM
White 84 SE Member
Posts: 812 From: Chicago, Illinois USA Registered: Nov 2008
I feel virtually retarded. I called Advanced Auto and they sell new rockers for $8 each and new push rods for $2 each. THIS would be the way to reduce lash...doh!
------------------ 84 Duke, Holley TBI, Manual Trans 4.10, CompuCam, White
[This message has been edited by White 84 SE (edited 09-30-2009).]
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07:48 PM
Patrick Member
Posts: 37633 From: Vancouver, British Columbia, Canada Registered: Apr 99
I feel virtually retarded. I called Advanced Auto and they sell new rockers for $8 each and new push rods for $2 each. THIS would be the way to reduce lash...doh!
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.
