The Iron Duke sounds like a tractor engine! (Page 1/2)
82-T/A [At Work] MAR 05, 08:57 AM
Guys, so I got a new (project) Fiero for my daughter, that I'll be going through with her. I'd only had a couple of 4 cyls over the years, and I'd completely forgotten that sound. It's not atrocious by any means, but I now remember that it basically sounds like a small diesel tractor engine. So, there are two things I'm trying to figure out:

1 - What causes this engine to sound like that? Is there any particular aspect of the design that makes it sound so jaggedy / clunky?
2 - How can I remedy it and make the engine sound a bit more fluid? I've not yet checked to see if this 85 has roller lifters, but I assume they can easily be adapted (I'll need to change the cam too, right?)


Thanks!
fieroguru MAR 05, 09:36 AM
Cam Gears, Non-adjustable valve train, TBI injector, piston slap, thin cylinder walls... basically the Iron Duke sound is designed in.
cvxjet MAR 05, 12:07 PM
I want to say; My 85 SE V6 sounded horrible after the Cat disintegrated...The exhaust was clogged with pieces of that cat (But no dogs!)

I took the exhaust off and, looking at a diagram of the muffler, started shaking the exhaust and got most of the crap out and it sounded much better.

Later, it started making more noise but only when lugging the engine (third or fourth at 1500 rpm (Floored)...Took it off and shook it out again, and then it sounded better again.

If you have "Cat crap" in your exhaust, you can tell by taking it off and shaking it; It will rattle! (Added note- the performance of the car did not suffer (Yes- I am amazed at that)

First shake-out;



Second shake-out;

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

Patrick MAR 05, 12:34 PM

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

...it basically sounds like a small diesel tractor engine.



Yep. After having several dukes, I was SO pleased with the sound of my first Fiero 2.8 V6 engine!
82-T/A [At Work] MAR 05, 01:08 PM

quote
Originally posted by fieroguru:

Cam Gears, Non-adjustable valve train, TBI injector, piston slap, thin cylinder walls... basically the Iron Duke sound is designed in.



Hahah... that's great. What is piston slap, I'd never heard of that?



quote
Originally posted by cvxjet:

I want to say; My 85 SE V6 sounded horrible after the Cat disintegrated...The exhaust was clogged with pieces of that cat (But no dogs!)

I took the exhaust off and, looking at a diagram of the muffler, started shaking the exhaust and got most of the crap out and it sounded much better.

Later, it started making more noise but only when lugging the engine (third or fourth at 1500 rpm (Floored)...Took it off and shook it out again, and then it sounded better again.

If you have "Cat crap" in your exhaust, you can tell by taking it off and shaking it; It will rattle! (Added note- the performance of the car did not suffer (Yes- I am amazed at that)




It literally looks like you're digging through fossils!



quote
Originally posted by Patrick:

Yep. After having several dukes, I was SO pleased with the sound of my first Fiero 2.8 V6 engine!



When I hear it outside of the car, it actually sounds a lot better than it does inside. Inside it sounds rickety. But when I see the car driving by, it sounds way better.
fieroguru MAR 05, 01:26 PM

quote
Originally posted by 82-T/A [At Work]:
Hahah... that's great. What is piston slap, I'd never heard of that?



Piston slap is when the clearance between the piston and the cylinder wall are too large and allows the piston to rock in the bore and the skirts slap the sides of cylinder bore. Most common on cold startups because that is when the clearances are the largest.
sleek fiero MAR 05, 02:46 PM
82-T/A just wondering if you might have a leaking exhaust gasket. I had one on my 2.8 and yes it sounded like an old tractor. Ha Ha
Spoon MAR 05, 06:26 PM
Replace your stock muffler with a FlowMaster or a Cherry Bomb. That will give you bragging rights and will override the Duke sound. Just don't accept any challenge's or show your hand.

PS: Most USPS trucks are running Dukes so you're in good company.

Spoon

------------------
"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

Patrick MAR 05, 06:44 PM

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

When I hear it outside of the car, it actually sounds a lot better than it does inside. Inside it sounds rickety. But when I see the car driving by, it sounds way better.



I dug into the archives for this. It's from my first year of autocross back in the summer of 2010... driving my 5-spd (swapped out the 4-spd), 90 rip-snortin' HP 4-banger '84 Fiero on street tires, before I added a rear sway bar. Video shot with a couple of $10 thumb-size eBay cameras.

The reason why I'm posting this video, is this is how a duke sounds with a GT (twin dual tips) exhaust system and aftermarket free-flow cat.

82-T/A [At Work] MAR 05, 09:16 PM

quote
Originally posted by fieroguru:

Piston slap is when the clearance between the piston and the cylinder wall are too large and allows the piston to rock in the bore and the skirts slap the sides of cylinder bore. Most common on cold startups because that is when the clearances are the largest.




LOL, that's great... hahah... I should have expected more from Pontiac. I know it's half a Pontiac 301, but does that mean Pontiac's small block is also **** ?



quote
Originally posted by sleek fiero:

82-T/A just wondering if you might have a leaking exhaust gasket. I had one on my 2.8 and yes it sounded like an old tractor. Ha Ha



Lol, yeah... I've had a cracked exhaust manifold in one years ago, and it made that ticking sound. The exhaust is actually pretty decent... the engine itself just has that "clackety" sound.



quote
Originally posted by Spoon:

Replace your stock muffler with a FlowMaster or a Cherry Bomb. That will give you bragging rights and will override the Duke sound. Just don't accept any challenge's or show your hand.

PS: Most USPS trucks are running Dukes so you're in good company.

Spoon



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. 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)?



quote
Originally posted by Patrick:

I dug into the archives for this. It's from my first year of autocross back in the summer of 2010... driving my 5-spd (swapped out the 4-spd), 90 rip-snortin' HP 4-banger '84 Fiero on street tires, before I added a rear sway bar. Video shot with a couple of $10 thumb-size eBay cameras.

The reason why I'm posting this video, is this is how a duke sounds with a GT (twin dual tips) exhaust system and aftermarket free-flow cat.




It's really not bad at all. That was still a good run, and funny.

My wife took it around the block, and hearing it from the outside, it actually sounded pretty cool.