D8h

Hello JGC 74

D8H -UK - 22A - increased to 270 hp with S/No 22A 01247 - year was 1966

D8H - US - 36A- increased to 235 hp at S/No 36A 01229 - year was 1966

D8H - US -46A - increased to 270 hp at S/No 46A 012885 0- year was 1966

D8H - Scotland - 52A was 235 hp only.

D8H - US - 68A - increased to 270 hp at S/no 68A 01209 in 1966


I hope that these canges by Serial Number answers your query's

Alan T Lewis
Christchurch
NEW ZEALAND

I think OM is more on the correct side for the 36A because there were alreadyover 3100 of them built buy end of 1960

OM & Willie are correct - Alan, you need to recheck, and maybe correct your info source. Here is the scan from the Caterpillar Product Bulletin of April 30, 1966, detailing the power increase of the U.S.-built D7E, D8H and the associated pipelayers .. along with the S/No's ..

D7E, D8H & pipelayers HP increase, 1966 .. http://img149.imageshack.us/img149/6097/d8hpowerincreasezx2.jpg

Late in the game the 46A's were also bumped to 300 Horse too. I am not sure where but it was late in the game.

Greg - Nowhere in my extensive Caterpillar information, can I find any reference to late model D8H's being increased to 300HP. The D8H was always rated at 270FHP, right up until the D8K appeared (which had a power boost to 310FHP).

Where you may have become confused, is perhaps in a reference, in the Oct 17, 1972 issue of the Caterpillar Product Bulletin, to engine modifications to the D8H engine, involving new fuel components and a new turbocharger.

In this article, Cat state that "The D8H has been fitted with a new fuel system, a new turbocharger, a new fuel filter and lines, a new fuel valve, and other new parts are used as well". This article goes on to note .. "Engine ratings and performance are unchanged" (my italics).

The upgrade occurred around mid-April 1972, and affected all models of D8H, as well as the 583H pipelayer. The upgrade applied to the following tractor S/No's ..

36A5485-up ..
4628137-up (inc. 46A27801) ..
68AXXXX-up (S/No unknown) ..
61A771-up (583H) ..

The confusion may have arisen in your mind, due to the fact, that Cat supplied temporary engine specifications in this PB, until new Rack Setting information could be supplied under the engine specifications guides.

The temporary specifications state a FHP rating of 299FHP (WITHOUT fan) .. at a NL speed of 1400RPM and a FL speed of 1280RPM. Note, that engine HP ratings without fan, are NOT classed as tractor HP ratings.

I thought the 68A was a UK tractor not a US one.
Later Bob

Bob, that's correct. I didn't say it was U.S.-built, I just stated that the engine upgrade applied to all D8H's in production at that time. It appears as if Caterpillar U.K.'s records were pretty lax, or they couldn't supply the S/N in time for the PB publication cut-off date .. because Cat just have an asterisk after the 68A S/N, and a footnote at the bottom, stating that the 68A changeover S/N is not known.

I remember the power increase in the mid 60,s and afterword started seeing counterbore cracks in a lot of 342 engines in late H and k series tractors