IXB5 Engine

Allan from PA · Nov 2, 2014

I am in the process of rebuilding a Hercules IXK3 engine using some parts from a IXB5 engine. The parts I am using from the 5 engine are the crankshaft and connecting rods which have the same part numbers as the 3. The aluminum pistons from the IXB5 engine, which I don't need, were all knurled on the skirts which I can understand. What I don't understand is all 4 pistons also have a saw cut straight up the skirt from the bottom of the skirt up to the ring lands. Why would they be like this? The engine bore is still at 3.250. Just curious, never saw this before but obviously it has been done. Thanks, Allan.

oliver90owner · Nov 3, 2014

Lots of ally pistons were like that, but usually the cut was diagonally from skirt to oil control ring groove, some on both sides of the same half/side of the piston. Scraped oil clearance might come to mind but not really need a long cut.

Perhaps to improve oiling on that side, maybe to allow the skirt to be 'bumped' a bit if clearance was tight.

I remember a friend dropping valve clearance seats in a set of pistons and he cut them on the wrong side. The manufacturer said just turn them around, although they had direction arrows on the piston crowns. Cannot remember if they had split skirts, mind.

Your ally pistons woudl likely be higher speed rating than C.I. ones.

MikeJM · Nov 3, 2014

Allan,
The saw cut you see was very common on those older engines, the purpose was to control expansion of the piston. The though was that the saw cut would mearly close up as the piston skirt heated up instead of expanding.

I guess you are probably working on a Cletrac or Oliver HG. I did the same thing years ago to my brothers HG, had a bad crank and everyone wanted a mint for a crank and I just happened to have an old IXB5 sitting on an old welder that was missing the cylinder head.

Allan from PA · Nov 3, 2014

Thank you for the replies. Mike you are correct on my project. Never have enough information. I always check the parts that I am using or want to save for correct condition. When I saw these pistons I just scratched my head. Thanks again, Allan.

Bob · Nov 3, 2014

.
All you need to know about split skits...

Allan from PA · Nov 4, 2014

Thanks Bob, interesting. Allan

IXB5 Engine

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