Help on a Chevy 350 rebuild

I am not a mechanic but I do like working on these things. I have "rebuilt" a few engines, mostly rings, bearings, valves, gaskets, etc. This time I thought I might go a step further. I am a rebuilding a 350 engine for my 72 Chev pickup. I usually have the cylinder numbers stamped on the rods and have the machine shop press on the new pistons. This time I had the rotating assembly balanced. That included some grinding on the big end of the rods. They removed my numbers. Now I have to figure out which pistons go on which side. The pistons are marked with a dot for the front but what is the correct orientation for the rods? I weakened and bought the HPBOOKS "How to rebuild your Small-block Chevy" for some help. On page 96, it does stress that there is a right way to do this but their description and the pictures suck and I can't tell which way is which. The picture shows two piston-rod assemblies that say the bearing tang grooves should be on the top side looking towards the front of the engine. Are these grooves where the rod bearings fit in to locate the bearing in the rod and keep them from turning with the shaft or are they the round holes on the other end of the bearing? If I look at other pictures in the book, it looks like the "bearing tang grooves" are opposite what the text is saying. Does anybody have a good detailed description of how these go together or good pictures or a good rebuild website that can help me out?

Reply to
William G.
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My factory shop manual says the "connecting rod bearing tang slots go on side opposite the camshaft" (toward the outside of the block). I would take this as the slot in the rod, not the holes. Either a dealer or independent parts house should have some pistions/rods in stock maybe you could look at.

Also, I would think that, if they balanced the rotating assembly then they should have taken into account which piston/rod went where LD

Reply to
LD

Those holes are sometimes called spitter holes. Their purpose is to throw oil at the camshaft lobes. So of course you install the rods so the holes end up facing into the center of the engine on both sides. Assuming you got everything back from the shop partially assembled, then you now have 4 piston / rod assy's with the holes on the left and 4 with them on the right.

If the shop balanced and resized the rods and you are using new pistons then it doesn't matter which cylinder gets which piston and rod assembly. Usually they do what is called a neutral balance. They find the lightest piston / rod combination and then shave the rest to match that. Once that is done they attach weights to the crank and it gets balanced by itself. Until the engine is assembled and run and a wear pattern begins any piston / rod can go into any position in the engine.

As you assemble you can stamp the sides of each rod and rod cap before you install it in the cylinder.

Also, I would think that, if they balanced the rotating assembly then they should have taken into account which piston/rod went where LD

Reply to
Rufus T. Firefly

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