I work at a machine shop and have some cnc horizontal boring mills at our facility. Would they be suitable for boring/honing the cylinders and decking the block to the same deck height between banks? I have a setup in mind and I could set the block on some parallels on the transmission side of the block so it sits level. I could then indicate the center of the block off of the main caps and that way, I would just have the program rotate the block 45 deg off centerline for the cylinder boring. I would be using a boring bar and bore the cylinders out to 3.904 and use a ball hone for the last thousand. Tips/opinions?

 

Anyone? My shop is not an automotive machine shop. We are a job shop and have small vertical cnc Acer mills, manual vertical mills, lathes and big cnc Tos Varnsdorf horizontal boring mills. We also have cnc and manual VTL machines and that's what I run.

 

Nothing?

 

ball hone not a cool idea for the last thousandth. when we bore blocks we leave atleast three to be finish honed . boring bar is a good idea and a torque plate is a good idea also using either bolts or studs depending upon what you are using in final assembly. also is crucial when decking the block measure from deck to boring bar in cylinder 1 and 7 get average and 2 and 8 get average make it as even as possible and I deck them before honing more precise that way atleast thats how I think. sorry if im not much help to you never used what you have at work but hopefully it helps a little if you want to question me on it you can pm or text if you want

 

again I dont like ball hones unless your just breaking a glaze down and re ringing a stock set up I like stone set ups

 

Not a good plan! You need to be able to square up the block from the crank journals to the deck. That is what mitchell is referring to. If the block cannot be squared from those points line honing or boring and surfacing will be in order to get the block ready to bore straight. This is assuming the block has been properly cleaned and inspected for cracks and defects first.

 

Well if I use a machinists square to check for deck to front/rear of block squareness and all is well there, what problems would there be with it? Isn't the oil pan surface machined square to the main cap area too? I don't mean a line boring bar, but a boring bar made for boring holes exactly to size. It is for the cylinders and I could use a hone set as well. Figured the ball hone would be faster and easier. A boring bar for a horizontal boring mill has 1 or 2 inserts that are adjusted out to the required diameter being bored. They are adjustable to 2 tenths of a thousandth. The machine itself can hold +/- .0005 tolerances pretty easily. Isn't the top of the block where the knock sensor cover goes also machined square with the block? That would be a good place to indicate the block to get 0 deg and index left or right 45 deg for the decking and facing of the block.

 

In short, NO!!!

Everything is relative to the Crank center line. There is no way to know if the pan rails are square without checking them from the crank.

I have a block with a bad deck on 1 side. I can only assume there was an issue with the machine when they originally machined this block. 1 side was already a little lower and after taking .010 of the decks, 1 side still has a low spot between the middle 2 cylinders. My machinist thought there was an issue with his machine so he tore it down and rebuilt it. He then remeasured with the same results.


BHJ sell's some stuff but it's not cheap. Maybe if you look at it you will get a better understanding of what's going on. They have some nice pictures and a good description.

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