Converting 1984-1986 Engines to Serpentine System (Page 1/1)
82-T/A [At Work] APR 06, 01:13 PM
So... someone graciously donated an engine to me, and I was under the impression that we were going to be able to convert my daughter's 1985 2.5 Iron Duke to the belt tensioner / serpentine system, and possibly even install a harmonic balancer, rather than use the old-school V-belt system which... well... basically sucks.

She's away on an orchestra trip, so I snuck a peak and removed the belt tensioner... only to realize that the three bolts that hold it on actually do go into the block itself, and not the brackets. On the 1984-1986 engine, there is a "block-off" plate to cover up where the water pump would normally go in a traditional "longitudinally" mounted version of the Iron Duke... you know, where the fan bolts to the waterpump pulley in a clutch-system. In any case, the block off plate used in the 84-86 Fieros is attached using 4 fine-threat machine bolts.

On the 1987-1988 Fiero duke engines, it's attached using 3 much larger fine-threat machine bolts. It essentially takes the place of the block-off plate and itself functions AS the block-off plate.

There's only ONE bolt that lines up, and that's the one in the upper-right hand corner, which COULD be drilled and re-tapped to the larger thread size. Unfortunately, they reinforced the block for this, and added more "meat" to the block in order to support this larger hole. The other two bolts are in a completely different spot.

Some thoughts I had is that I could have the factory tensioner machined down so that I could keep the factory block-off plate (which has the timing hole), and perhaps then just drill holes in the factory tensioner bracket... and use the existing bolt holes. All of that WOULD work, however, the concern then is... would those four (smaller) machine bolts be able to support the torque / stress of the belt tensioner. My thought is NO.

Now, I've NOT given up hope, yet... my thoughts are this, I could have someone make a 1/8th inch plate that would connect the factory (1987) bracket to the water-pump bracket on the other side, and even have it connect to the lower A/C compressor bracket (1987) where it attaches.. This would provide the major support needed for a belt tensioner. We could simply weld a nut on the top where the belt tensioner pulley goes into. For the sake of using those extra bolts, four holes could be drilled into this plate in order for the factory 1984-1985 blockoff plate bolts to go through.

I'm thinking this wouldn't be a huge undertaking. I'd need to fabricate something in cardboard, and then find a place that would be willing to cut it out for me. Or... I could simply just buy some flat stock, and then buy a metal cutting band saw and do it myself.


Thoughts?

I know there's the... "not worth it," but let me tell you... I've had 3-4 Iron Dukes, and I cannot stand V-belts.


EDIT: to say that for those who don't know... the block off plate on the 84-86 has four bolts, but these bolts are basically double-ended. So there's bolts with a nut, and then bolts coming out the other end. The point of this is because there's a plastic bracket (and some other things), that attach to it. In the 87-88 model years, they re-routed most of the electrical wiring in the car to go along the back, rather than have the wiring go down the front of the motor (to go to the A/C and a few other things). So I would be re-routing it anyway, and would not be using this plastic bracket anyway.

[This message has been edited by 82-T/A [At Work] (edited 04-06-2024).]

theogre APR 06, 07:48 PM
When people "hate V belts" is a problem w/ the setup or more likely problem w/ the Installer cause Too Tight or Too Loose & belt suffers in Seconds.

You "hate V belts" yet have no clue about serpents on Dukes in Fiero & other Model Lines...

1. Doubt the tensioner arm is actually good & likely not finding a new replacement. Bad Arm = Belt Track is Off &/or Belt Tension is uneven across the width.
TFS "cornered the market" for Fiero Tensioner & help jack up the price to 2x 3x & more.
RD tried to sell a mod to other tensioner to fit Fiero for this reason but had issues too.

2. Has AC? Good luck finding a compressor & brackets to do this. AC pulley Must be in line w/ all other & exact alignment or Belt will Fail & Fast because 3 pulleys w/o space to try to handle even smallest alignment problem.
Have worse Alignment problems after messing w/ WP & its pulley because issues there...

Even W/O AC or Bypassing AC, WP pulley must have Alignment Check because replacing it changes Tolerance Stacking that can Effect Pulley Alignment enough to cause Belt Wear even when have longer belt section between pulleys.

3. Finding Serpent w/ right size often isn't easy now.
Even w/ OE setup on 87-88 Fiero dukes w/ OE PN current Belts from any brand have problems, worse on AC, because OE tensioner have a Very Narrow on Belt Size & Too long = slips, too short & tensioner breaks.
All in aftermarket said somewhere that Printed Size/Spec is Not Exact belt size. Change Brand/Model is bad enough but even buying a belt today is not exact same as old belt or belt you get next year even from same brand etc.

Plus most or all belt makers change the "rubber" type to EPDM so now the serpents often make No Noise while they die.

see cave, serpent belt
shares many problems w/ V but adds own problems.

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

82-T/A [At Work] APR 06, 08:58 PM

quote
Originally posted by theogre:

When people "hate V belts" is a problem w/ the setup or more likely problem w/ the Installer cause Too Tight or Too Loose & belt suffers in Seconds.

You "hate V belts" yet have no clue about serpents on Dukes in Fiero & other Model Lines...

1. Doubt the tensioner arm is actually good & likely not finding a new replacement. Bad Arm = Belt Track is Off &/or Belt Tension is uneven across the width.
TFS "cornered the market" for Fiero Tensioner & help jack up the price to 2x 3x & more.
RD tried to sell a mod to other tensioner to fit Fiero for this reason but had issues too.

2. Has AC? Good luck finding a compressor & brackets to do this. AC pulley Must be in line w/ all other & exact alignment or Belt will Fail & Fast because 3 pulleys w/o space to try to handle even smallest alignment problem.
Have worse Alignment problems after messing w/ WP & its pulley because issues there...

Even W/O AC or Bypassing AC, WP pulley must have Alignment Check because replacing it changes Tolerance Stacking that can Effect Pulley Alignment enough to cause Belt Wear even when have longer belt section between pulleys.

3. Finding Serpent w/ right size often isn't easy now.
Even w/ OE setup on 87-88 Fiero dukes w/ OE PN current Belts from any brand have problems, worse on AC, because OE tensioner have a Very Narrow on Belt Size & Too long = slips, too short & tensioner breaks.
All in aftermarket said somewhere that Printed Size/Spec is Not Exact belt size. Change Brand/Model is bad enough but even buying a belt today is not exact same as old belt or belt you get next year even from same brand etc.

Plus most or all belt makers change the "rubber" type to EPDM so now the serpents often make No Noise while they die.

see cave, serpent belt
shares many problems w/ V but adds own problems.





Hi Ogre,

#1 - I have a good original (tensioner is still good), and I also bought the Rodney Dickman replacement tensioner (never used).

#2 - I have a complete 1988 Iron Duke with all the accessories installed. I plan on swapping everything over. From what I can tell, everything from the 88 will swap onto the 85, with exception...
- The tensioner (obviously, as mentioned above)
- A small alternator support bar that connects the back of the alternator to the intake manifold. This will need to be bent at a 90 degree angle as the intakes are different from 86-87.

BUT... there's a possibility that I actually don't have a tensioner at all, and instead... this bracket I make, all I do is merely install an "idler" pulley. I can actually KEEP the alternator bracket from the 1985, go with the newer alternator and serpentine pulley, and then simply use the alternator as the adjustment.


EDIT: I'm planning on also upgrading to the newer 86+ compressor system. If I need to, I will upgrade to the later 1986 2m4 ECM.

[This message has been edited by 82-T/A [At Work] (edited 04-06-2024).]

82-T/A [At Work] APR 07, 04:08 PM
So, I'm going to update this, and I'll have my daughter make a video on it. But so far, here is what I've determined...

1 - The factory belt tensioner from 1987-1988 will NOT bolt up to a 1986 and older engine block. The bolt holes are substantially different, and in a different location.

2 - Everything on the "right" side of the engine (forward part of the motor when installed), will bolt up the same from 1984-1988.

3 - Everything on the "left" side of the engine (rear part of the motor when installed), will bolt up to the head and block, but requires modification because the intakes are different.

4 - Crank hubs are different. It doesn't seem like the 88 pulley bolts on to anything, so much as it's held in place by the crank bolt.


- BREAK -

I have some options. One, someone would need to make a custom belt tensioner bracket... but these brackets are really thick, and need to be able to properly support the stress of the belt system. Two, I could eliminate the belt tensioner system all together, and instead, simply install an Idler pulley somewhere on the front, and then I can simply use the serpentine belt system, but use the 84-86 alternator bracket, with the new C130 alternator... which is adjustable for the belt tension. This way, I can switch to a serpentine system, get the benefits of a "single belt" system, use the newer compressor, newer alternator, AND be able to use a harmonic balancer, while still being able to use the original coolant block-off plate with the timing hole.

The ONLY thing I'll need to fabricate, will be the idler pulley, and then determine the best belt length for the system.
jelly2m8 APR 08, 01:31 AM
Serpentine belt is far superior to V Belts which is why you do not see modern cars with V belts. It comes down to is the cost of the 2.5l belt tensioner worth it to you?

[This message has been edited by jelly2m8 (edited 04-08-2024).]

82-T/A [At Work] APR 08, 11:04 AM

quote
Originally posted by jelly2m8:

Serpentine belt is far superior to V Belts which is why you do not see modern cars with V belts. It comes down to is the cost of the 2.5l belt tensioner worth it to you?





I agree... I'm dead-set on getting a working serpentine system for my daughter's duke.

I think I've settled on the idea of getting an idler pulley, and continuing to use the alternator as the adjustment point for belt tension. Technically, without anything else, I'd be able to use the serpentine belt system, it just wouldn't be much of a serpentine system, so I just need to figure out the right placement for an idler pulley.

I went ahead and bought Rodney Dickman's "85-87 V-6 Power Pulley Kits": https://rodneydickman.com/p...6e2f9bd96a6a9f488f96

I realize this is for the V6, and I already have the idler pulley on my V6 (which works really well), but I figured I could kill two birds with one purchase here... I don't have the newer underdrive pulleys for my V6 (which this kit comes with), and I figured I could use the new Idler pulley here for my daughter's Iron Duke. If need be, I can simply cut / weld it into a larger bracket that I make. I already ordered a flat stock of 1/4" plate steel, which I intend to cut into a bracket. So we'll see... I want something that is the absolute least complicated, but that is also reliable. My hope is that it's something I can then simply give my plans to Rodney for free, and maybe if interested, he can make a bunch of them for other people.

What I'm looking at now... EVERYTHING is available off the shelf "except" the idler pulley bracket. You can order a new C-130 alternator that already has the new pulley and will work with the factory brackets. You can also order a new water pump that also already has the new pulley installed. You can also buy a serpentine crank pulley off eBay from any number of other years, and then... finally, for the A/C compressor, if you want to convert to the newer V5 compressor, you just need the brackets from a factory Fiero, OR... you can still also buy the DA6 compressor with the serpentine belt pulley as well.

So other than replacing your alternator, water pump, and compressor, the only thing you'd actually need is the idler pulley bracket and the correct belt length.