hi i bought a 230 six an all the rods where off the pistons the rods have a flat top with a bump or lump on one side of the top does that go toward the water pump or what??? thank you for any advice

Most pistons have a small indention in the piston top toward the edge to designate the front of the piston, that indention faces the front of the engine. Sometimes they even have an "F" cast into the piston on the side by the wrist pin to also designate that side facing toward the front of the engine.

CNC Dude - I think he needs to know which way the rods go on the crank.
ie: facing which way - front or back with the lump he talks about.
I do'nt know,otherwise I would tell you Rev.ken.


regards,Rod

Bearing tangs go opposite the camshaft. Older engines had an oil squirt port around the rod bolt near the cam and corresponding holes in the bearing inserts to lube the camshaft.

Pretty sure about this but not 100%. Can someone confirm?

Chilton manual says: 1. Notch or "F" on piston towards front of engine. 2. Rod oil spurt hole towards camshaft side of engine. 3. Heavy side of rod bearing towards front of engine.

And what might be the result/symptoms if one or more of the items or assemblies was installed incorrectly? 'Just Askin'

Can someone expand on this?

Think i got it now if you look @ the rods from the side where the rod bearings go on the rod not the cap theres a little v shape notch that spits oil @ the cam ?? sound right? and somewhere i read they lean to one side to help with piston slap

As best I can remember, the offset is in the piston pin location to help prevent piston slap, not in rod, something about leverage. I vaguely remember that some stock class drag racers in the 60s used to install their pistons backwards on the small block Chevys (flat tops of course). This was supposed to raise peak HP to come in at a higher RPM. Not sure if it worked or not.

How about it CNC Dude, are you old enough to know about this?

WillH, the rod beam is not perfectly aligned with the centerline of the big end bore :the narrow side of the big end bore goes toward the rear of the engine and the wide (heavy) side goes toward the front....when you look up at the underside of the piston on assembly (if everything is correct) the pinbore will be more or less centered under the piston to equalize the load....when we turned the pistons around on the v things only the piston was reversed; the rod was installed normally, that kept the load centered.....the six cylinder rod is basically the same dimensions as the small journal 283 rod with the exception of the big end width; you do not want unequal loads on one of these or they will make funny looking drain holes in the pan....fats

Your absolutely correct Eddie, that was a trick done by a lot of racers to change the wrist pin offset direction. The pistons wrist pin bores are offset from the factory to reduce piston slap. You also can get a slight increase in deck height by turning the pistons around backwards, if you can stand the piston slap :D.

Thanks Fats!

Greetings . . .

Here's a great article describing why piston pins are offset:
Motorcycles Sacred Cows #17

On a lot of after-market pistons I have seen, there is a little nick machined into the wide side of the piston - which is the opposite side of the crank @TDC when the piston is about to start it's major thrust.

With a pressed in rod is there a really a front or back? The offset is in the wrist pin placement on the piston not the rod . . . no?

On the stove bolts the rods have a wrist pin bolt which is designed to be installed on the wide/cam side so it is opposite of the major thrust.

With pressed in rods does it really matter?

regards,
stock49