My 280S is burning oil. I will either have to rebuild the old M130 or find a good used replacement engine. Obviously, a used M130 will be an easy job but I was thinking about a V8 (3.5 or 4.5). How difficult is it to replace the M130 with a V8 (M116 or M117)? Will I need to upgrade the suspension due to the extra weight of the V8s? What about the auto transmission and differential?
Thanks.

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280S, 1969
250C, 1972

I believe the 3.5's and 4.5's had heavier front springs. You can try it without changing them, but your front might sit low.

The tranny probably won't handle the 3.5's or 4.5's power or its power curve well if it would fit. The rearend ratio on a 3.5 is taller than a normal 280, a 4.5 taller still. You'll probably want to change that so you don't get 8MPG on the highways with a screaming V8.

There's a chance you might have to relocate the brake booster, too, if it's one of the older models that have it where it'd interfere with the larger engine. Peter (psfred) knows the year cutoff, I don't.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

this particular swap is well covered in the archives. Putting in a v8 means replaceing everything under the hood. The steering gear was changed around to accomidate the larger engine. The tranny is completely different in size, strength and shift points. The suspension is much more robust for the extra nose weight.

You can put any mercedes straight-6 in that car with few changes. One being the transmission, unless your new engine is close in performance to the original (different valve body configurations).

-CTH

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