AC 426 engine questions

Is there a difference in tractor engine and combine engine internals ? Are the wrist pins bigger ? Is the crankshaft a steel product ? What kind of injector pump was used on a combine 426 engine ? I have heard all 7000 series tractors have a steel crank from the factory, is this true ? How about the connecting rods ? Are all 426,s oil pumps crank driven ?  Just a few things Im wondering about, Im slowly building a pulling motor ;  another one ; how big of a flywheel [ diameter] does a 426 have in a 7000 series tractor ?

some of the combines had a heavier crank in them made in west germany hard to find also had bigger rods and pins. Probaly the engines in the n6. I have taken alot of 426s apart and it seems like a crap shoot what your gonna find inside.

The 7000 series had 1 1/2" wrist pins & 4-ring pistons.  The engine changed with the "670" series.  At that time, the wrist pins became 1 3/4", and the pistons were 3-ring for less friction.  The cranks in the 3500 family of engines were Japanese, German, & some other countries as well.  Each had a different part #, but were all interchangeable. The 7080 engine being different, as it had the heavy counterbalance crank, etc.  & was called 3750 I believe. The 7060 engine was called 3700 I believe.  The 670 family were also from several different countries, but the German ones seemed to last the best in our area,  The 670 HI units had a heavier counterbalance set-up on it & that crank weighed about 75# more than the lighter ones.  They were used in 8050, 8070, N-6 combines & possibly others.  It would interchange with the 670 series crank with smaller counterbalance sizewise,should be a bit stronger.  It also had the viscous front dampener .  The blocks changed from 3500 in D-21, 210 & 220, & to the 670 in 7000 series, in that the outside had various bossed areas & bolt holes moved, etc.  Some had water outlets in middle of block for water filter lines (8050, 8070, later N-6), while others had only the front & rear ports.  The oil coolers changed dramatically, as did the oil filter blocks.  Water pumps & water flow changed, especially on "intercooled" engines. Cylinder heads looked like older models, but in later years they all received thicker iron above compression chambers, new casting #'s, & thus became a few pounds heavier.  Early 3500 flywheels had 4 bolts & 2 dowell pins.  Later ones had 6 bolts.  Pins could be removed from early ones, drilled out holes & tap threads & make work as 6 bolt units. Sorry for the long post, but there are a few more refinements, but these are what I can recall just now.  The 3500 series received a crank driven oil pump with the 7000 series tractors as well

Bosch injectors didn't happen until late 1980, but, there were customers who bought the conversion kits for older tractors.

I would say thats what the previous owner had done then. I blew a injector line with the allis injectors and thought I could just put a line on off that tractor but the lines were routed alot different. I was just told that it had the bosch injectors.

Allis built the early style, only the injection pump was stanadyne(roosa). Roosa pumps were still used with the bosch/american bosch bar-stock injectors though. 

     Shows how very little your machine shop knows farm equipment doesn't it???

They are not saying it is a common practice. They have heard of it being done. I am asking if anyone on here has done it and if so can i get some info?