4.2 harmonic balancer

Swaping 258 to 4.0, 4.0 parts to 258 etc!
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Shrek
Posts: 9
Joined: December 12th, 2018, 8:43 am
Vehicle Year: 1989
Vehicle Make: Jeep
Vehicle Model: Wrangler

4.2 harmonic balancer

Post by Shrek »

I have a 89 4.2, and would like to convert form a "V" belt to a serpentine belt.
Will a 4.0 harmonic balancer fit and function on my 4.2 crank? I am in the process of putting a 4.0 head on a rebuilt block.

TIA
rlinares40
Where's the "any" key?
Where's the "any" key?
Posts: 27
Joined: December 3rd, 2020, 9:38 am

Re: 4.2 harmonic balancer

Post by rlinares40 »

Shrek wrote: June 18th, 2021, 8:41 am I have a 89 4.2, and would like to convert form a "V" belt to a serpentine belt.
Will a 4.0 harmonic balancer fit and function on my 4.2 crank? I am in the process of putting a 4.0 head on a rebuilt block.

TIA
I would believe so as we can use your crankshafts on our 4.0s. where I can see you running into the problem is with the accessories, they are driven by a "V" belt pulley correct?
rlinares40
Where's the "any" key?
Where's the "any" key?
Posts: 27
Joined: December 3rd, 2020, 9:38 am

Re: 4.2 harmonic balancer

Post by rlinares40 »

rlinares40 wrote: June 18th, 2021, 9:50 am
Shrek wrote: June 18th, 2021, 8:41 am I have a 89 4.2, and would like to convert form a "V" belt to a serpentine belt.
Will a 4.0 harmonic balancer fit and function on my 4.2 crank? I am in the process of putting a 4.0 head on a rebuilt block.

TIA
I would believe so as we can use your crankshafts on our 4.0s. where I can see you running into the problem is with the accessories, they are driven by a "V" belt pulley correct?
meaning it does no good to have a serpentine harmonic balancer when your alternator pulley is "V" styled.
Shrek
Posts: 9
Joined: December 12th, 2018, 8:43 am
Vehicle Year: 1989
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: 4.2 harmonic balancer

Post by Shrek »

Thank you for the reply. :cheers:

I am changing the power steering pump, water pump, and the alternator to a serpentine belt. An idler pulley will need to be installed as well.

I spoke with Russ Pottenger, and found that I can use a 4.0 balancer, but will need a spacer, which I purchased from him.
Azhunter
Posts: 2
Joined: February 23rd, 2021, 8:42 pm
Vehicle Year: 1988
Vehicle Make: jeep
Vehicle Model: Wrangler

Re: 4.2 harmonic balancer

Post by Azhunter »

If you use the harmonic balancer for the 2.5 4cyl. it is the same part number as the 4.2 serpentine balancer and everything will line up right and you wont need the spacer.
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