Machining your own rods..

PsdPullerJr · Nov 21, 2013

Are you planning on doing heat treat and cyro or anything? Im in the same boat, if I had the extra coin to put a motor together right now I'd make my own rods at work. Not sure what material I would go with either. Are you thinking I beam or H beam? Are you gonna make the rod and end cap and bolt them together and do a final machine and hone the bores? I know many have talked about the piston to head clearance and how the factory specs suck and have wondered if it were possible to make the rods a little longer or shorter to come up with perfect clearance (if there is one lol)

silverpsd_06 · Nov 22, 2013

I don't know exactly what the plan is yet probably machine the end cap and rod separate with a .020" small diameter then drill both bolt them together flat and make the finish pass. I'd like to find a way to heat treat them. The only rod I have to design this set off of is the stockers. May take a look at the clearances while in the motor and see where some meat might be added to help with strength.

backwoodsboy · Nov 22, 2013

Pick up some literature, and read it. There are plenty of SAE endorsed publications on the metallurgy and machining processes pertaining to con-rods.
There is a lot more to it than taking a stock rod and making a replica in a different alloy.

Pertaining to the previous two posts:
You do NOT want to machine your rod and end cap as two separate pieces. Anyone want to tell me why?

TyCorr · Nov 22, 2013

Alignment issues...

PsdPullerJr · Nov 22, 2013

How are you gonna machine it as a single piece? Even so it's 2 pieces one way or the other you can have issues. My thought was to put small dowel pins in to locate the cap to the rod and do a final machine.

mandkole · Nov 22, 2013

At PACCAR Engine Co., where they build the new MX 13L for Kenworth/PB trucks (test engine pic in my avatar), they do a lot of machining in plant of many components (heads, conrods, block/crank/cam finishing, etc). The conrod is machined one piece and the cap is pressure cracked off to insure perfect alignment and no movement after torque. An amazing process and has a fair amount of science behind it.

Good luck to the OP--

09stroker · Nov 22, 2013

mandkole said:
At PACCAR Engine Co., where they build the new MX 13L for Kenworth/PB trucks (test engine pic in my avatar), they do a lot of machining in plant of many components (heads, conrods, block/crank/cam finishing, etc). The conrod is machined one piece and the cap is pressure cracked off to insure perfect alignment and no movement after torque. An amazing process and has a fair amount of science behind it.

Good luck to the OP--

That is ONE way connecting rods are made. 6.0 & 6.4 connecting rods are made this way too.

There is also connecting rods with locating dowels to keep them aligned and from moving like stated above.

hawgdoctor · Nov 26, 2013

Yes, but with the cracked cap design it also adds strength by the interlocking surface area of the peaks, and valleys. Allows no movement of the two pieces also. Very good for high load/ rpm apps. Even if you were to cryo/ heat treat the 400 I would rather see the 4340. More consistent grain structure is also why it is more popular for rods. Just my two cents.....