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#4111976 - 06/08/21 04:25 PM Powermaster 8-57140: opinions please
sgc2c Offline

Registered: 08/12/13
Posts: 140
Loc: Boca Raton Florida
Is the Powermaster 8-57140 a drop-in replacement for my stock alternator?
I have a 1990 Grand Marquis LS with the stock weak alternator.
This Powermaster is allegedly 140 Amps. Looks like a good upgrade.

Is it a 3g?

I’d like to try it if it’s a straight-up simple replacement.
Opinions, pros and cons please …
Thank you.

#4111992 - 06/08/21 05:41 PM Re: Powermaster 8-57140: opinions please [Re: sgc2c]
Bellwestern80 Offline

CVN Discord: Edsel
Over the Hill

Registered: 07/01/11
Posts: 3988
Loc: Evans, Georgia
That Powermaster is a 2G styled alternator, but it's configured to work in a one-wire setup, so no need for the factory harness.

However, I'd recommend the use of a proper 3G or 6G alternator. A 3G uses the factory voltage regulator connector, you just need the single wire connector to the stator to splice on to it.

The 6G needs a completely new connector, but only uses two wires instead of the three like the 3G.

Both need a new charge cable run to the starter solenoid as the factory charge cable is not sufficient enough to carry the increased load. The use of a 175 amp Mega fuse in an inline holder is recommended.

My Cars:
-1964 Mercury Comet 202 (116K Miles | 170 I6) - Awaiting Repairs in a Cozy Garage
-1987 Mercury Colony Park LS (330K Miles | H.O. 302) - March 2017 POTM Winner & November 2019 POTM Winner
-1997 Mercury Grand Marquis LS (225K Miles | nPI 4.6) - The Daily Workhorse & April 2013 POTM Winner

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