Any one old enough to remember Chryslers Lean Burn should be able to remember how
finicky it was to tune--mostly because there was little info made available to help ubderstand
how it worked--or in most cases didn't. Was found mostly on the B block 400 in the late 70's.
And the engine received a bad reputation as a dog--which it deserved. But emission standards
created it-sort of. Very detuned---extremely low compression rating of 8.2 and depending on
poor casting standards for cylinder heads with wide CC variations in combustion chambers,
some engines were in the neighborhood of 7.8 compression. Only produced 195 hp & 305 ft lbs
torque on a good day as a 2 barrel, the 4 barrel made 255 hp. But the four barrel wasn't much
help being the fact it was a plastic center body Thermo Quad which had a tendency for cracking,
warping. And on top of that it had the same issue the LA318 had at tdc, a piston with .130 still
below the deck at tdc. Which created a issue for building any compression with changing pistons,
{No body offered a replacement that had a higher compression height}.
So people were decking blocks and heads and intake manifolds to gain compression. The thing
is the 400 is the same B block as a 383 using the same stroke 3.380, only it has a very large
bore 4.342. So for many years no one bothered much with the 400, most were turned into
scrap. Then finally about 7/8 years ago Keith Black started producing a piston that is only .030
below deck at TDC, with a .039 gasket and 75cc chamber it's right at 10 on compression, 84cc
gets 9.3:1. And with a mild cam, intake 375 hp easy.
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