question concerning engine machining

I was preparing a set of rods and pistons for use in my substitute refresh motor yesterday and a thought came to me again that had popped up many times before.

Here it is for all of you engineers and "really know how to work with steel" types out there.

What is the process by which the foundry/machine works get that tiny drilling off the connecting rod big end out to the side and half way up the rod to deliver the cylinder oil cooling spray? It is so tiny and has to be pushed through such a length of high grade steel that I can't see a machine actually drilling the thing. Then again how could it be made into the casting?

Inquiring minds want to know. :-)

Jack

A "gun drill" was what we used at Deere for such an application.
Here a bushing is used to support the long drill with coolant delivered through drill tip...

http://www.sterlinggundrills.com/index.shtml

Thanks Jon! I never woulda thunk it. LOL Jack

money, money money. thats how. imagine the machining on making such a drill bit?

I add drilled feed hole for press fit rods when converted to floating and a bushing is added ( I never been one to float pins on steel) but anyway, with a small drilling I use a cobalt drill and set the mill up to run slooooow, slow and steady, which always beats fast and snap :) Connecting rods in the MGB are more than likely EN16 steel or better, so it's tough stuff. In Darryl's old motor, looked like a rod bolt failed, it smack the piston against the head hard enough to break the pin out of the piston, the rod bent in a bow shape but did not break which is a testimony to how tough they are.

Confused here Hap.

Are you speaking of the full floater set up with bronze bushings in the little ends? If so what do you mean by drilling a feed hole. Are you speaking of drilling a hole the full length of the rod from the big end right up to the little end? Zowwie!

BTW: I got a pretty good deal on a set of full skirt five ring pistons but I am going to trash the rings that came with them in favor of Deves. My thought on the full skirt jobbies was that the lone oil control ring way down toward the bottom would be just right to get a better grip on things in the dingle berry honed non-bored cylinders. With the OEM short skirt pistons having been in there since dirt, the lower part of the cylinder should have very little wear. These pistons are a little heavier than the short skirt four ring units but I'm not building this for speed. I had rather have a solid torque lump to glide around the mountains behind. Ditto on the rods. They are OEM angle parting units. Again, I know that they are heavier but without looking for five grand and above I suppose that they will work just fine.

Comments on the pistons appreciated.

Jack

twigworker Wrote:

I bumped this for you Jack, because after I read what I wrote I saw I didn't state myself clearly. Read the part about drilling a small oil feed hole in the top of the rod. On the 948,1098, MGB and even some Triumphs rods there is a verey small drilling at the side of the rod at the end of the beam as it comes back into big end. I fiquire this is there for one or two reason, it could be to splash the clyinder but more then likely I bet it is for oil bleed off.

I had the machine shop convert my 18V rods to floating by reaming the small end and installing the bushing and drilling the hole. The guy looked at me like he was dealing with a skitzoid lunatic! I just had to post!

the hole drilled in the rod big end is for cooling the piston bottom (like diesels) and secondary to cyl walls for long ring life...racing engines also cross drill the crank main journals and/or use full circle main bearings.as a normal crank has interupped flow....Golf