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4.2 harmonic balancer

Posted: June 18th, 2021, 8:41 am
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

Re: 4.2 harmonic balancer

Posted: June 18th, 2021, 9:50 am
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?

Re: 4.2 harmonic balancer

Posted: June 18th, 2021, 9:52 am
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.

Re: 4.2 harmonic balancer

Posted: June 20th, 2021, 5:14 am
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.

Re: 4.2 harmonic balancer

Posted: August 18th, 2021, 5:32 pm
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.