Quote:
Originally Posted by suginami
Also, sometime around 1984, all U.S. 3.8 liter engines were fitted with dual row timing chains from the factory.
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The 380 engine gets a bad rep (well deserved) over the US timing chain and poor performance. Not all 380's have a single chain, they can be converted, and once done it's no worse in that area than a 560. The performance of the US 380 can be blamed on the compression (a little) and the cam (a LOT). I've put Euro cams in a 380 I'm rebuilding, and the lobes are radically different. The US 380 lobes are incredibly pointy with very high ramps, which no doubt leads to the 5500 RPM limit and fast-wear on those cams. I will say that the M116 is little physically smaller than the M117, which might matter. A comparison of the intake manifolds is very revealing.
I suspect but can't prove that if one were to put US 420 cams in a 380 engine and advance the cams a bit, there would probably be a 25-30 HP surprise in it.