Small block 340 engine for sale and some questions...

Dartswinger70 said

I have always thought the 340 "turned into" the 360. Sort of, it definitely was transformed in the name of emissions. I am curious how well the later 340 performed compared to the early 340. I have had 70s era 318s that were stock except for a cam and header etc that ran really well. Fun on the street anyway. I would have to think the later 340 ran good for what it was. of course in terms of "sale value" the early one is the one to have. Just because it has all the "good " internals. Something as simple as the early high comp pistons vs the later flat tops makes a difference for example.

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The early 340s definitely had a little more pep in their step due to the higher CR and the X-heads. The Hi-po exhaust manifolds helped a lot as well, for those that didn't have headers. My early ('69) 340 had the Carter AVS and performed really well despite being a high mileage motor. My '72 was no slouch either, despite being de-rated from 275 to 240 HP. I suspect the TQ helped a bit in that regard.
FWIW, I also had a pre-'70 318 topped with a Holley 2300 2bbl that ran like a scalded dog. The "good internals" are a fairly easy fix; just go back to 10:1 pistons and slap on a set of Eddy heads with 2.02s and there you are.