Help Me Id This Buick Harmonic Balancer

Hey All! I have been dealing with an engine vibration and think it might be the harmonic balancer.
My engine is a 231 Even Fire Buick, casting number 25514290.
The harmonic balancer/damper on the engine now has the numbers 2550 1700 stamped into it and uses 6 bolts to hold the crank pulley.

I ordered a Dorman 594-142 as a replacement since that's supposed to fit the early 80's 231's according to the catalogs, but the new damper only has 3 threaded holes and no register for the crank pulley. I attached a couple pictures of the back of the damper that's currently on the car, and the front face with the 6 bolt holes.
The crank pulley register measures 2.1225" and the bolt hole pattern is clearance holes for 5/16" bolts on a 2-7/8" BCD.

So I guess my question is, what replacement part should I order?

 

This is where I go.

https://damperdudes.net/harmonic-balancers/buick/buick-231-3.8l-v6-1977-88-even-fire/

 

I guess I am just a little surprised that NAPA auto parts, O'rielly Auto and Dorman all got this wrong, or are there multiple flavors of harmonic balancer available for these engines?
I have been using a 1982 Buick Regal as my test search, but the Dorman 594-142 seems to be the one that is always suggested for any Buick 231 from 1977-1985(ish) when I think they swapped over to a serpentine belt.
I am fine with buying the damper from Damper-Dudes, I am just trying to understand what I have VS what the auto parts stores say I should have.
Thanks!

 

Buick dealership? Or find a Buick parts book online and see what the GM PN is for your engine. Maybe try TA Performance, or a Buick forum. It's Dorman that's optimistically listing their part's coverage all the way back to 1978. The sellers are just accepting what Dorman tells them about the part. I'd guess there is no direct aftermarket replacement part for an even-fire 231 with V belts.

Damper Dude may want your core, to rebuild it.

 

The casting number of your block could be a ‘78-‘81 231, ‘82-‘86 231, or ‘80-‘84 229. Are you sure you don’t have a 229? Just a possibility. Do you know what vehicle your engine actually came from? Your oil pan shows the earlier version timing cover with the flat front edge used in the late ‘70s.
-Donny

 

Keys5a,

The engine swap was performed by a mechanic in 1990 along with a lot of poorly done "upgrades". The engine was rebuilt by Densmore Engines. The engine build sheet only says "231 Buick" on it, but no year or any other useful information. I wish I knew more about the motor. I don't trust that any single component on the engine is original.
Here is another picture of the motor for reference.

 

One more of Harmonic Balancer and the crank pulley that was on the engine (probably NOT original).

 

Its a 79 or later. 2gv carb. Has this vibration always been there?

 

Rich,

The vibration was not there before we sent the Jeep out to be restored. We didn't get any documentation from the restoration shop, so I really don't know what was re-used, what is new and what was just found laying around the shop. It's partially my fault for not taking good photos of everything before it shipped out. I can say that the vibration got a bit better with the aluminum pulley, so I figured why not replace the dampener next and see if things get better

 

Just throwing darts here, is the distributor correct? even vs odd?

 

I'm wondering about the flywheel. Even fire flywheels ( factory) are not common, there are aftermarket ones. If it has an oddfire flywheel that was not at a minimum zero balanced or preferably balanced with the rotating assembly, you could have vibration issues. Engine mounts could also be suspect.

 

That's what I was thinking too. The even fire would have come with a damper, but probably not a flywheel. They most likely used a Dauntless flywheel and didn't have it rebalanced for an even fire engine.

 

How bad of a vibration would the wrong flywheel have? I imagine that the vibration would be pretty violent. The vibration I am dealing with is more of an annoyance than anything.

 

When do you feel it? Does it increase with RPM? Does it increase with speed? Does it go away? Have you ran it without the belt on it? The distributor, wires are correct and in order?

 

It would typically be the same as a damper. The OEMs tend to have the same amount of imbalance at both ends of the crank.

 

When do you feel it? Does it increase with RPM? Does it increase with speed? Does it go away? Have you ran it without the belt on it? The distributor, wires are correct and in order?

RattyFlatty,
I don't have a tachometer on my Jeep, but it's most prevalent in the mid-rpms, maybe 2-3,000rpm. It is completely rpm dependent, not speed related at all. The cabin will vibrate with the car stopped and revving the engine. Clutch in/out, gear selection etc. doesn't have an impact.
Distributor is correct, timing is good enough, wires are in correct order. The engine doesn't run poorly at all. I mean, it's no speed demon, but I got it running alright.

I have NOT tried running the engine without a belt, but that's not a bad idea and is easy to do.

It would typically be the same as a damper. The OEMs tend to have the same amount of imbalance at both ends of the crank.
I just had a shop install a new clutch system, bellhousing, throwout, resurface flywheel etc just a few months ago... I really should have had this addressed at that time since the issue was there previously as well. It's not horrible, so if it turns out to be a flywheel issue I will probably let it slide until the engine falls apart or needs to come out for a different reason. My wife will bury me in the backyard if I take the Jeep apart again! Replacing the pulley made a fairly significant improvement, which is what got me thinking a new harmonic balancer might be in order.

Going back to my original question: All of the auto parts stores, including NAPA insisted the Dorman 594-142 should be appropriate for my engine. I don't necessarily want to just replace what is currently on the Jeep as I have very little faith that it's the right part to begin with. Does the damper on the Jeep now look appropriate for a 1980(ish) Buick 231? Visually it looks similiar to the one on DamperDudes website.

 

There should be a counterweight cast in the hub of the balancer. I remember decades ago comparing a couple different Buick balancers and noting differences. I expect a 225 and a 231 even-fire, and maybe another was on the bench for comparison, but I don’t remember the details.
-Donny