I'll keep looking for the factory swap information.
The following is from the ATHS website in 2011:
CATERPILLAR 1676 - D336 4.5" bore, 5.5" stroke 60deg V8
D336 was used in 621, 621J motor tractor scrapers and the 980 wheel loader.
The 621 was 300hp and air to air aftercooling
The 980 wheel loader was 225hp and had no aftercooling, ( I think it was 225hp ?)
The engine gave reasonable service in the 980's, the 980B was powered by a 3306 engine.
But the 621 / 621J was released with the D336 engine and at the time a new design
8 speed transmission which had 2 converter gears and 6 direct drive gears and would
believe some engine failures were a result of transmission operation (operator error).
If they, the operator changed down incorrectly the engine would overspeed and usually at
about 2700rpm the gear driven air compressor ( air brakes) would self destruct.
With poor service life and difficult repair options as a result of the overhead camshaft
drives CATERPILLAR released a engine replacement option using a 3306 6 cylinder engine
at 270hp which result in a performance loss of 1 gear.
We had several 1676 engines down here, 1 in a KW, 1 in a ATKINSON, 1 in a OSKOSH and
another fitted to a ATLAS COPCO oil free air compressor.
The KW disappeared ? the OSKOSH was a service truck on a dam job and we did not see it.
The ATKINSON was a twin steer bogie drive prime mover built especially for heavy haulage
by L ARTHUR a trucking company that worked for CATERPILLAR moving all the machines of
the whalf to the dealer.
We rebuilt it once after the bigend bearings failed, on disassembly it suffered the same problems
as other D336 had which was the connecting rods thrusting into the webbs of the crankshaft.
Several years later CATERPILLAR released the D346 5.4" bore 6.5" stroke 60 deg V8 for larger
scrapers and dump trucks and athough much bigger and heavier engine looks very very similar
in appearance and component layout.
