Line Bore or Not

Thanks to all who replyed to my previous post on line bore. The only ? that nobody addressed was, where is it written in any Ford repair manual that oil pump replacement required a line bore be performed. Can anyone tell me where to find it in writing,or is it something a machnic should know?

An oil pump replacement does not require a line bore of the engine,you need to have the oil pump gears reamed to match your housing at New Holland or somewhere that has the proper fixture to hold it in place while reaming it.The only time you would have to line bore is if you replaced the front bearing assembly that has the oil pump in it.

(quoted from post at 16:41:33 03/26/13) Thanks to all who replyed to my previous post on line bore. The only ? that nobody addressed was, where is it written in any Ford repair manual that oil pump replacement required a line bore be performed. Can anyone tell me where to find it in writing,or is it something a machnic should know?

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I have never seen it stated in any Ford manual. But any book on basic engine rebuilding tells you that main bearing caps are not interchangeable and must be kept in the same position and orientation they were in when the engine was manufactured. Since the oil pump housing is part of the front main bearing cap if you do replace it you have to mate the new bearing cap to the block. Line boring is how you do that.

TOH

I think it is the assumption made back then (when folks did lots of rebuilds) that you would just know. I know that when anything related to the mains changes from what it left the factory with it has to be align bored - that's only because of my years dealing with old cars. The caps were put on (including oil pump in this case) and it was bored to "align" everything perfectly for the crank. If you do any switching out the pieces you put in there would be aligned to a different engine. It has to be realigned. If you don't you may have spots where it is too loose and spots where it is too tight causing a hotspot. Have you noticed that you haven't ever found an engine where one journal was ground different than the others (one main bearing is 20 thousandths over while the others are 10 thousandths over)? That's because they are all done together just big enough to true up the worst one.

Like I say, I think it was assumption that folks would know that. Rebuilding engines was much more common when these were much newer. Heck, I know of folks that did letter series Farmalls every two years and those are stout engines. They knew the inside of that engine like it was an old shoe.

Beleive the most common situation is when folks go from stock 9/16" width oil pump gear to 3/4" width oil pump gear, which requires a replacement crankshaft cap.