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  • June 20, 2024, 04:11:27 AM

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Author Topic: Harmonic balancers  (Read 1257 times)

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Offline 86erfixer

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Harmonic balancers
« on: March 23, 2022, 02:03:26 PM »
So I've been working on project Daize, measuring completion. All that's left is front axle regearing and tuning. That being said, I finally swapped out the worn out 390 Holley for the new quick fuel 4bbl. To my surprise the engine fired and maintained idle without any adjustments. When I decided to throw my timing light at it, with the idle set to about 750 and vac advance disconnected, I was relatively shocked that by ear I had previously set timing to 23° at idle. Background: two years ago or so when I first drove this bird out of it's would be grave, I couldn't get her to accelerate (load or no load) with the vac advance hooked up. After some fine tuning and a cam/intake swap, I couldn't use the advance at all. All the same, I was at my wits end, away with the vac gauge and light. I set it to ear and drove it. Not only started and accelerated well but cruised flawlessly at 21 mpg without any ping or bog or other ill manners. I seem to be in disbelief after checking total timing(~42) that this could be correct. I've yet to do so but I'm going to verify tdc marks on my balancer this week. Seems probable to me that it's spun given my idle timing. .......which leads me to my next question, the car is an 86 wagon with a 258 and a 5 speed. V-belt and a/c equipped, where in the heck do I find a damper in the case that mine has spun???

Offline vangremlin

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Re: Harmonic balancers
« Reply #1 on: March 23, 2022, 04:00:45 PM »
From my understanding, it's not uncommon for an old balancer to spin like that and tuning by ear can be more effective than using a timing light.

I just did a quick check and did not see a harmonic balancer for a 1986 Eagle available.  However, they do list one for an 86 Jeep with a 258.  I swapped an 85 Jeep engine into my 81 Eagle, can't remember if we kept the Jeep balancer on it (probably) rather than swapping the Eagle one on. 

Maybe someone on the forum may have a used one available, including me lol. 
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

Offline AMC of Houston

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Re: Harmonic balancers
« Reply #2 on: March 23, 2022, 09:04:53 PM »
The same balancer has been used over many years under many different part numbers.  The Jeep units are indeed identical.  You can get both the v-belt or serp belt versions from the Jeepers (like Quadratec or Morris 4x4) for about $75.
George G.
'81 Eagle Sundancer
'85 Eagle Waggie
1960 1902 Rambler Replica
'64 American
'70 AMX (Big Bad Blue), '70 AMX (White)
'77 Gremlin
'78 Pacer Coupe, '78 Pacer Wagon
'79 Pacer Wagon
'73 Jensen Interceptor
'86 Audi 5000 Turbo
'98 Aston Martin DB7
'09 Nissan Titan
'10 Nissan Maxima

Offline 86erfixer

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Re: Harmonic balancers
« Reply #3 on: March 24, 2022, 12:28:13 AM »
I thank you kindly guys! I saw there are several part numbers available with a cj7 matching that of an '80 Eagle but I wanted to be sure. Hopefully my findings will indicate the balancer is fine and my bird just likes alot of timing. I did push it a bit to the limit on cam selection! But still 23° initially seems like Soo much!


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