4.2L Serpentine Swap?

[pyro]

Looking for info on doing a serpentine belt swap on my '81 258. I figured it would be good to get a thread going on the subject for future reference. Post up any and all info.

[Stuka]

I have a factory serpentine setup, it works fine except that tightening it is really a horrible setup. It's not a spring loaded idler like newer setups.


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[pyro]

any idea what all is involved in a v-belt to serpentine swap? can you put up some pics for comparison?

[Cecil14]

Well, in theory you could swap everything from a 4.0L setup onto your 258. Get the 1cm crank spacer to go behind the 4.0L balancer and you should be in business. Like Stuka says, the tensioning setup is abysmal, mine uses the power steering pump. There are a couple spring loaded tensioners available aftermarket (Hesco is one I can think of) but they're kinda crazy expensive. I believe the newer 4.0L setups also went to a spring loaded unit, though I haven't really looked.

And of course you'll need pulleys for your various accessories.

aa

[Stuka]

Mine uses the alternator, and the way it pivots is weird. Requires a few tightening sessions. Tighten, run it, tighten some more, run it some more, etc.


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[carnuck]

I have the whole 4.0L in my '84 J10. Adjuster is on the PS and uses a screw adjuster as well as the alt adjustment to use different size belts over a small range.

[Stuka]

I have the whole 4.0L in my '84 J10. Adjuster is on the PS and uses a screw adjuster as well as the alt adjustment to use different size belts over a small range.

Yeah the 4.0 setup was better than the 258's. And the 258 only got it for 1-2 years as I recall.

[carnuck]

My '83 and '84 J10s had it as well as '84 up Eagles (if they were built in Canada, they got the serp belt) I prefer the cheaper AC Delco alt so I'm modding the brackets for mine to work with the 250 amp one I picked up (and 8 tooth serp belt from a cop car)