So, I know the duke is noisy, I've seen that documented in other posts. My question is can tightening the rocker nuts help? Can running 10w40 help? Must I just grin and bear it?

Mine is a later 1986, until warm it sounds great, once warm it sounds like its full of marbles.

Ha! Make a cat bark and then we will talk.

I wouldnt tighten the nuts as it will wear the rockers. You can convert to SBC roller rockers, though. Dont ask me how, but I remember someone going over it.

I have the 88-coupe which is noisy as all get out, your 86 may be different. I did tighten my rocker bolts down to the specified 24 ft./lbs torque, very little change. I am in process of replacing my roller lifters and checking the other train components thinking that I may solve the noise issue in that fashion. I'm sorry but it'll be awhile before I can finish the project to report on the results.

Back when my Fiero was Duke-powered, I tried to quiet the valvetrain rattle. I tried different torque on the rocker bolts (from 15 ft-lb to 30 ft-lb). I also tried different engine oil viscosities (from 5w30 up to 20w50). Neither had any noticeable effect. But I found the "roll up the windows and turn up the stereo" approach to be very effective.

Comp cams make a stud that fits the Duke Head. just remove the rocker stud and screw in the replacement part from Comp cams. I believe the part number is CCA-4554-16. Comp cams can also sell you the locks. Remember that the stock roller ratio is 1.75:1 and that ratio is hard to find.

[This message has been edited by fotofrank (edited 06-19-2007).]

i have an 88 it was quiet,i loaned it to a friend now not so quiet,but still one one of the quieter dukes the 88 seems to be quieter than most dukes ,some hate the 88 crank but it is the way to go you must rebuild to tight specifications use synthetic oil .the only way to make it really quiet is to replace it or use the 88 engine i will have my club members listen to mine at the next club meeting,,,on older worn engines run STP ha ha. i am not sure why my engine is quieter than most ..but the 88 seems quieter of course i run a cherry bomb so mayby i can not hear engine,i had an s 10 head at one time and it seem quieter,if i win the lottery?? after the girl friends implants,Im going for a balanced engine with a real worked over s10 head.. i will report to duke lovers on the forum NO not on the implants, the engine you pervs

WHAT! You can't report on BOTH! You're a tease man..... Have fun though, heh, heh, heh....

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carpe diem

quote Originally posted by fotofrank: Comp cams make a stud that fits the Duke Head. just remove the rocker stud and screw in the replacement part from Comp cams. I believe the part number is CCA-4554-16. Comp cams can also sell you the locks. Remember that the stock roller ratio is 1.75:1 and that ratio is hard to find.

Serious? Someone may have a fix for it? What kind of work is involved in doing this, can you do it by just removing the valvecover then? I don't have experience replacing rocker studs.

I believe the stud kit he mentioned is for roller rockers. I'm not sure if it'll work with the stock Duke rockers. And BTW, if you decide to get roller rockers for your Duke, look for 1.7:1 ratio big block chevy rockers.

quote Originally posted by fotofrank: Comp cams make a stud that fits the Duke Head. just remove the rocker stud and screw in the replacement part from Comp cams. I believe the part number is CCA-4554-16. Comp cams can also sell you the locks. Remember that the stock roller ratio is 1.75:1 and that ratio is hard to find.

Thats the stuff.

Are Duke valves really that big or are the cam lobes really small?

Ok, I hope we can hear more details.

Also, its kind of scary to replace things in an engine that runs really well, just is noisey. We would need to pin down for sure what size would be needed, also if its ok to do this to an engine already "worn in" 216, 000 miles. Have you done this?

windows up radio loud that the fix iv had my duke for years and had them in other cars but for some reson the fiero is LOUD my celebrty you could not here it run lol but i do know that iv replaced cam and tran parts and it did not help i think it is in the crank ( damn 84 to 86 cranks )

i do know one things that helped is a new head when i had the block out i cleand the oil jurnels and wow did that help it is real messy but you can try running it with out the valvecover on and see if all the rockers are geting oil i repet it messy ( i used a pice of tin and made a block for the oil ) and if you are not grting oild to some will somthing is pluged

brandon

I had a 1990 grand am 2.5 that sounded like my Fiero does. I thought it was unsolvable too, but one day a hole rusted in my timing cover causeing rapid oil loss onto the ground, (after a winter of being stored). When I took it to get fixed it came back sounding nice and quiet, they said something about a part in the timing chain area slapping into the timing cover, and over the years wearing it thin, then it rusted thru during storage. Maybe thats what some Fieros have also? Sounds kinda like someone tap dancing.

I bet its not a quick thing to get into the timing cover and see....

[This message has been edited by 2.5 (edited 06-20-2007).]

quote Originally posted by 2.5: I had a 1990 grand am 2.5 that sounded like my Fiero does. I thought it was unsolvable too, but one day a hole rusted in my timing cover causeing rapid oil loss onto the ground, (after a winter of being stored). When I took it to get fixed it came back sounding nice and quiet, they said something about a part in the timing chain area slapping into the timing cover, and over the years wearing it thin, then it rusted thru during storage. Maybe thats what some Fieros have also? Sounds kinda like someone tap dancing. I bet its not a quick thing to get into the timing cover and see....

The Iron Duke as used in the Fiero has no timing chain; the camshaft is gear driven.

it takes about 10 min to get the timing cover off a 13 mm box end and a 10mm socket that it

Well, thats cool, maybe rules that out. Unless the Grand Am was too, I just meant "timing cover" and maybe shouldn't have said chain. The Grand Am thing happened quite a while ago.

the only way to quiet the duke is to rebuild it and use tight specifications.one of the replacement gear sets is quieter than other any one do this that knows??..i have never done a full rebuild on the duke,but years of working on motorcycles proved that tight tolerence works but you must take long break in period..the engine must be driven at different speeds,, the first drive just to break in engine,carefull!! the money required to build a quiet duke is not worth it this is a work horse engine ,,better to improve OVERALL performance to give miles per gallon, smoothness, and icrease performance ,the duke can deliver 40mpg with 5 speed and s 10 head i was shooting for 45 mpg but never got close to this you need straight thru muffler (not loud) i am playing with mufflers right now,have move to cat position and am checking for heat in cab and clearence to ground.. you will be surprised how quiet the cherry bomb is on a duke I like the sound acel in 3rd to floor but quiet enough to idle beside po lice car

They don't call the Duke the "Clattering Tower of Power" for nothing.*


*This comment was NOT intended to be a Duke bash. Someone else posted that here, a couple of years ago. I LMAO!
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Raydar
88 4.9 Formula IMSA Fasback..........................88 3.4 coupe -soon to be something other than red

Read Nealz Nuze! Praise the Lowered!

[This message has been edited by Raydar (edited 06-20-2007).]

I've got a duke powered Fiero too. It's got 144,000 miles on it and still runs good. I started checking to see where all the noise was coming from and discovered that the noisiest thing on the engine is the fuel injector. Put your stethoscope on the air filter while it's running and you'll see what I mean.

Other than that, there's not much sound insulation around this little engine, and the noisy parts are behind thin stamped steel covers. It was made to be cheap and lightweight, not a luxury car engine. Many have commented on the noisy valve train - thin covers and no valve adjustment is what causes it. If you wanted to quiet down the valve train, you'd need to find / install custom length push rods to get the valve lash right.

But hey, these little engines perform pretty well all things considered - and they get good gas mileage. I put a low restriction cat and dual exhaust on my duke; it still rattles just as much but the exhaust drowns it out. Sounds pretty nice, actually.

I know nothing yet about this engine. I bought an 88 with a sick one. I'm in the planing process of building an engine for it, what block, crank, head etc. But I do have a 91 S10, with a duke. Other than it makes a Diesel like noise now, after my Honda Civic driving son had it one day, I would think it quiet.

I have not been into the rockers of my truck, so I don't know if I'm talking through my hat or not. But, it seem like the general consensus is this noise comes from the valve train. This maybe, but you could not go by me. So, if it is indeed from the valve train, it sounds as though adjustable rockers is the cure. Not tight enough? If this is the case, could you not put a shim between the rkr bolt an the rkr pivot to tighten it up a bit?

I notice that installing BB Chev roller rkrs, is not uncommon. I've used them racing, thought they would be nice for the street to help with valve guide wear. But, on a sub 5000 RPM engine, wow, you guys have to much money. Not trying to shake anyone tree, but I could think of better use for the green stuff.

This just my opinion, and it may change when I have a running specimen in my newly acquired car.

Since I have an 88 S10 with the 2.5, 88k on it but the body is all rusted to heck, good donor? Is head swapping pretty straight forward to do? As far as experience,I took heads off my old 69 Chevy's 327 and had them rebuilt at a shop, then put them back on. Is there any modifications that need to be done or are the S10 / Fiero 2.5 pretty much the same, all same hookups? Better flow or something gives better mpg? My Fiero is an 86.

[This message has been edited by 2.5 (edited 06-21-2007).]

Sorry to get you enthused and then crush dream of easy hp but forgot that this will not work on your engine the set up is different works on 87 & 88 can not remember what works on your year but it is different also care must be used to remove and replace studs this can lead to trip to shop with broken stud HMMMM wonder who did this on pontiac engine..the heat vents release heat and noise you can wrap exhaust with heat tape this will redeuce heat and small noise abatement I am thinking about a thin insulation install under the air cleaner to go with my cherry bomb experiment.. i just do not have time to check out insulation install inside valve cover with new types of insulation best screw the noise go for slight hp and mpg improvement, you should have average mechanical skill to screw around with trying to make an engine quiet if not there are many projects that are easier stan

quote Originally posted by 2.5: Serious? Someone may have a fix for it? What kind of work is involved in doing this, can you do it by just removing the valve cover then? I don't have experience replacing rocker studs.

A cheeper fix is replacing the stamped rockers with roller tip rockers. Again they must be 1.75:1 ratio. Use the stock shoulder bolts, that hold the stamped rockers in place, the rocker nut and a spacer to keep the roller tip rocker tight. Torque the whole she bang as listed in the Haynes manual.

To use full roller rockers either install a modified SD 4 valve cover (no pvc valve opening) and modified air cleaner cover (no room) or grind the full roller rockers to fit the stock valve cover. Simply screw the required studs in the location of the rocker bolts, place the rockers on the studs and place the locks over the rockers. Do NOT tighten the locks but leave the rockers loose or the car will NOT start. Once the car is running slowly tighten the locks, one rocker at a time, till the chatter is gone. Simple !!!

best thing to do is make it sould like mine lol punch a hole in the cat takes care of that but kina sounds like a propane forklift

Nice, Zetabird

I took off the valve cover and ran the engine, listening with a stethescope, definately pushrods and rockers making alot of noise. I could hear the echo off the apartment next door LOL.

quote [B]Originally posted by Whuffo:[/B Many have commented on the noisy valve train - thin covers and no valve adjustment is what causes it. If you wanted to quiet down the valve train, you'd need to find / install custom length push rods to get the valve lash right.

I was thinking about the same idea earlier today, maybe 2 MM longer pushrods on my noisy Duke. I did take the loudest rocker off and will let our shop mechanic and the auto parts store manager look at it. Maybe I've got some wear but if I can use longer push rods, why not?

What does everyone think about longer rods?

i like my little duke indy but i have never been able to stop the gumball machine sound that eminates from its insides when it rolls down the road

it's kinda like how seafood stinks a lot, but people still love to eat it

[This message has been edited by FieroMonkey (edited 06-28-2007).]

Ok, so I'm new to Duke engines, lets think outside of the box for a minute, in other words, don't laugh too loud at me for this next thought.

What if, instead of longer pushrods, just mill a fraction off the bottom of the push rod guides? That would in effect lower the entire rocker assembly that sits on top taking up any slack causing the noise. A machine shop should be able to mill a little off, isn't that called "decking"? I did not want to torque down more than 24 ft/lbs on the rocker bolts, didn't want them too tight causing friction heat and wear. The more that I was tightening the quieter it got so lets go and talk to the machine shop guys about a little custom work.

My thought is that the lifter is hydraulic like the V-6 engine and should easily be able to compensate for a little lash.

Ok, is this a dumb idea or what?

Mine only makes noise at Idle, same with my 90 Grandam when i had it.

quote Originally posted by 2.5: Mine only makes noise at Idle, same with my 90 Grandam when i had it.

Roller vs hydraulic lifters?

This might be the smartest dumb idea that I have had yet.

I'm trying to take up the slack in the valve, rocker, pushrods that is causing the ticking noise; right? The options are mill the head or longer pushrods or shave the pushrod guides or,,,,,,,,

,,,,,ready,,,,,?

,,,,,, simply use a washer under the rocker bolt head.

A thin hardened washer under the rocker bolt head would lower the rocker and easily take up any slack that wear has caused over the years. Correct me if I'm wrong but since we're dealing with hydraulic lifters; this is like resetting the valve lash so to speak.

Man alive, I want to try this out but I'm stuck at work!

I replaced my catalytic converter with a 2.5 inch Cherry Bomb Turbo muffler. There's a 2.5 inch pipe from the muffler that exits the car infront of the passenger side rear wheel. Oh yeah, I play the stereo LOUD!

Jetman, let me know how that goes! What year is yours? Mine is 86.

[This message has been edited by 2.5 (edited 06-30-2007).]

STOP longer push rods are available this engine was originally a chevy vega engine chevy s have the most speed equipment available of any car on earth I have seen post about the longer pushrods concerning later duke head to early duke check this out before milling any thing of course any modification to improve duke is of interest to me these push rods were from a sbc I think.. I install an s10 head that came with different push rods no longer have them ..racers use to race this engine on short track so there must be stuff available stan

From working on various engines for quite a long while, I've found that some engines just run quieter than others. I've seen some 2.8L that are noisy despite setting the valve ash precisely with a dial gauge. Noise is usually caused by some amount of wear. Sometimes this wear is the sign of impending failure and sometimes it is just an inherent quality of the engine. It could be excessive clearance in the lifter bore, worn rockers, a hung up lifter, piston slap, a worn valve guide, bearing noise exhaust noise from headers or even a small exhaust leak that sounds like a tick. Get out the stethoscope and start listening around.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 06-30-2007).]

quote Originally posted by 2.5: Jetman, let me know how that goes! What year is yours? Mine is 86.

I got real nervous when the engine didn't immediately start knowing that we are on uncharted waters so I stopped and pulled the washers out. In theory should be ok if I had washers that were only 1/4 as thick as the ones that you see in the picture. Turns out that the car was a bit flooded but nevertheless, I decided not to proceede any further and went back with stock configuration.

You know that it would be nice to find an inexpensive quick fix, especially for us appartment dwellers that aren't supposed to do "repairs" on their vehicles in the parking lot. A quick fix would be temporary until I could perform proper repairs, the engine runs strong, just noisey. I would love to go ahead and freshen up the upper end, just have to wait, to many other projects going on.

Ya mine runs strong too, which rules out things like a hung up lifter.

We all know some engines are noisier, we are trying to figure out how to get the 2.5 quieter.

I like the washer idea, and know the lifters "should" adjust.

BUT, if the washers are too thick they may not let the valves close completly at higher RPM. shouldn't happen, but could and that would be bad.

Can we find out what the stock clearance between the rocker and valve on a 87-87 duke? Maybe someone with a low mileage or rebuild could check with a feeler gauge.

Then the washers could be sized correctly to match stock clearances.

Something don't sound right with the washer test. If you torque the bolt to 24 lbs/ft then everything will still be the same as before. The difference is the bolt is just not as far down into the head. Am I off in my thinking?