The Iron Duke sounds like a tractor engine! (Page 2/2)
Patrick MAR 05, 10:00 PM

quote
Originally posted by 82-T/A [At Work]:

It's been a really long time since I've had a 4 cyl. This one has 149k miles on it. I don't know if it's original, but it actually runs quite well... but I think I'm still going to pull it out and rebuild it since it'll be part of the learning experience for my daughter.



If the previous owner has been using 10w-30 engine oil, try 15w-40 before you dig into the engine. It may surprise you and be a lot less "clackety". Heck, I used 20w-50 plus original formula STP (real thick!) in my first Fiero (a very tired '87 duke) many years ago.



quote
Originally posted by 82-T/A [At Work]:

I wonder if there's anything I can do to it to make it more refined (other than roller lifters, if it doesn't already have them)?



I believe of all the dukes, only the 84's originally came with flat tappets, but someone like The Ogre will know for sure.

[This message has been edited by Patrick (edited 03-05-2023).]

theogre MAR 05, 11:13 PM
Valve Train often does make noise but often Not because Dukes are not adjustable.
"Low mile" 10+ year old engines often have not change the oil enough then crap build up in the valve lifters and they won't work right.

Can clean the lifters or replace them and solve many problems.
Can remove lifter cover w/o messing w/ intake manifold. Will need to remove distributor/dis and oil sender.

You cannot install GM and most roller setups in dukes not made for it. Oil holes for flat lifter won't work.

------------------
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

Patrick MAR 06, 03:44 AM

quote
Originally posted by theogre:

...because Dukes are not adjustable.



Well... yes and no. Isn't it possible to tighten up the valve train (if loose due to wear) by putting thin shims under the rocker arm bolts?

[EDIT] Ah... I found the thread. Quieting a Duke Engine...

Some guy in that 14 year old thread even created this nice diagram.

[This message has been edited by Patrick (edited 03-06-2023).]

82-T/A [At Work] MAR 06, 07:46 AM

quote
Originally posted by Patrick:

If the previous owner has been using 10w-30 engine oil, try 15w-40 before you dig into the engine. It may surprise you and be a lot less "clackety". Heck, I used 20w-50 plus original formula STP (real thick!) in my first Fiero (a very tired '87 duke) many years ago.

I believe of all the dukes, only the 84's originally came with flat tappets, but someone like The Ogre will know for sure.





I thought about that, but I want my daughter to have the experience of pulling the engine and rebuilding it. It's such a simple motor, that other than machining work, I may even attempt to have us assemble it as well. I've lapped valves before back in the day, and shoot... the cyl head is so simple.

As for the lifters... well... it's a bit more complicated than that. From what I remember, the whole first run of 85s also had flat-tappets. I discovered this when I went to order new lifters for an 85 2m4 that I rescued from auction back in... 1997? I went to NAPA, and they sold me roller-lifters... which I thought were super cool. I went to install them, and the engine in the 85 had flat-tappet. I checked the VIN on the block, and the engine was original. I made a post about it under Peter Zurich's old Fiero List mail thing, and was told that the first run of 85 Fieros (most of which were white, for whatever reason), had that. But I'm hoping mine have roller lifters, because I can literally change those out at any point.

I'll take your advice though and put in heavier oil, just to keep the engine running smooth while we work on all the other components of the car.
theogre MAR 06, 12:44 PM

quote
Originally posted by Patrick:
Well... yes and no. Isn't it possible to tighten up the valve train (if loose due to wear) by putting thin shims under the rocker arm bolts?

[EDIT] Ah... I found the thread. Quieting a Duke Engine...

Some guy in that 14 year old thread even created this nice diagram.


I'm well aware of shim use and ignore it because most problems here it's wear or other problems. More so since cleaning and replacing duke lifters.

1. Lifters on Dukes, V6, V8 and more need to be installed so the lifter is very slightly compressed all of their life. This is so the clip holding the "guts" in Never see impact and rest of valve never go total slack. If you "Shim them" as posted and get that wrong then the lifters can be compress too far and hit the bottom causing major problems. more in #4...
2. Because the the "top" clip of the lifters will Break if beaten by the lifter "guts" hitting it.
3. Do Not think the lifters behaves exact same w/ engine running or off.
..A. Lifters see and need oil pressure to meet pressure spec all the time to work right. W/o system pressure, only spring(s) in the lifters keeps some tension on the rest of parts. So you may "feel" more slack w/ engine stop vs actual slack/tension on valve parts on a running engine.
..B. Lifters can trap dirt and/or get "Varnish" problems and the "Guts" won't move right even when have good oil pressure to them. Bottom area can trap dirt likely because slows oil flow enough so dirt sinks. (Sim to Air in Coolant system get trapped in the radiator then purge by heat cycling.)
4. Because Duke is Non Adjustable... The Lifters very likely allow more travel in them. This save "Valve Lash" adjustments like for "Fiero" V6 and some others. Any that say adjust intake valves 1 way and exhaust valves another is because exhaust valve stems grow more when engine is hot. Duke lifters just don't care when that happens. Duke is not rare for hydro lifters not needing valve adjustments. Ford 2.3 4 cyl w/ OH Cam and hydro lifters is same. (Used in 73+ Pinto and many others Including 85 Mustang SVO Turbo.)

I replace OE Duke w/ another w/ < 100,000 miles a few years ago. Late year I then had to fix other issues and look at the lifters...
W/o oil pressure was near impossible to compress them. I mean Even w/ a "bench press" hard to compress.
Once compress enough to remove the top clip, the guts didn't pop out.
Took over 1 hour for strong solvents and careful working the guts out of main body.
Once guts were out the bottom was full of trash fighting compressing of top of oil "glue" binding the inner and main body.
Cleaning 1 lifter ate 2-3 Hours of my time alone.
Did again to 2nd and had same issues and said not worth Days to clean the rest.

New lifters installed cause major noise reduction.
To the point can now hear the Injector noise some. Duke Injector has TBI w/ Air Cleaner case to act as sounding board to amplify that sound and nothing easy will stop that. Some 300/220 and 700 series TBI injectors just make noise then others. Can't hear it on my 87 w/ deck lid close.

88 Duke tries to fight other noise(s) but many balancer motors have other problem and can self destruct with little warning. Not just GM motors either. Is why many part sources have made Balancer Eliminator Kits for other engines. Example: Gen1 Chrysler Mini Van etc w/ some 4cyl engine... Balancer loose bearings then the shaft itself then breaks timing chains and no oil pressure or the pistons wreck the valves. If you get noise warning and install a kit fast then the motor can last years more and get some more noise/vibration.
Raydar MAR 06, 10:06 PM
They don't call it the "clattering tower of power" for no good reason.

My 88 is noisy too. Some days, more than others.
theogre MAR 07, 05:57 PM
Yes, USPS LLV and many others use "same" engine w/ same problems even tho you often can't swap VIN R U A or E versions between different models.
R U is for FWD cars. even then can't swap because mounting holes and more are different.
A E is for small trucks including LLV and many of these are RWD w/ "standard" front engine setups.
Side Note: Truck versions have ECM controlled EGR and vac valve but seems doesn't have the vac switch that famously trips DTC 32 on V6. Or not as part of the valve.
fieroguru MAR 07, 07:05 PM

quote
Originally posted by Raydar:
They don't call it the "clattering tower of power" for no good reason.
.



Steve, that is funny!
82-T/A [At Work] MAR 08, 03:04 PM
Hearing it from the outside really gives a different perspective. I actually (uniquely) like the sound of the Fiero Iron Duke... but it sounds horrendous INSIDE the car. Which is to say, that having the V6... and being inside the car, is like music (inside and outside).

I think I'll take a lot of input from that post: https://www.fiero.nl/forum/...160323-2-103494.html ... and try to adapt as many of those things as I can. I don't expect the inside of the car will sound amazing, but if I can get rid of the clattering sound (which I don't really hear from the exhaust or really outside the car at all). The motor runs really well... I mean, pretty smooth for a Duke... I'd just completely forgotten what that was like.

Dumb question... at what point did it become the "Tech-4?" I bought the Tech-4 sticker from Rodney, and I realize now that the Tech-4 might refer to the 1987-1988 models.
theogre MAR 08, 04:42 PM

quote
Originally posted by 82-T/A [At Work]:
Dumb question... at what point did it become the "Tech-4?" I bought the Tech-4 sticker from Rodney, and I realize now that the Tech-4 might refer to the 1987-1988 models.

87- 92 model year dukes had that label.
It's not same engine as 86 and older but looks similar and shares some parts.
Big things you find all has DIS and 700 TBI + Many 88+ are balancer engines w/ oil filter in the oil pan.
had other updates/upgrades too can't see easy or at all like even later versions, 91-92, had Timing Chains not gears like older ones. Can't convert old engines to this.