Connecting rods

 

I use a lot of Farmall H and 350 rods in the 201 and 226 based engines to give a good strong rod and keep a decent rod to stroke ratio.  These rods have a canted cap and clear well in the 201 engines out to abut 5.4" stroke with a bit of work, in the 226 engines they clear well at 5.5" stroke and with some block clearanceing and sleve notching 5.75" stroke.  By 6" they are to tight for comfort.  They use a large diameter crankpin, 2.29" for a nice strong crankshaft when done.  The rods are 8" center to center, 350 rods work great for pistons with a .927 pin and H rods work well for .990 wrist pins.  The H rods have a large enough wrist pin bore in the end that sometimes I weld a solid slug in them and offset bore a new hole to change the length + or - .150 and with a smaller pin can be moved .200 longer or shorter.

 

I clearance the rods in the milling machine and then a bunch of hand work.  I use a stronger rod bolt than they originally had and countersink it in the cap for added clearance.

 

It's a bunch of work to finish out a set of take out rods into a final product.  Make bushings for the end, clearance the rods, size the bores, balance, and sometimes it takes a lot to get these old rods to balance.  They are soft, and if needed for the application it's a trip to the heat treater.  All of this adds cost for the end user.

 

I have a local fella makeing billet rods for me in his small CNC shop.   I did my homework on material selection and grain structure for rods.  I'd love to make them but I don't have a CNC or the countless time to stand by my manual machine.  Though a bit more costly they sure are easier to work with.  The added benefit of a narrow crankpin also makes for a stronger end product.  It's easy to change the length, pin size and cap angle for clearance issues or for special applications. 

 

Here's a few pictures of some of the rods.

 

Billet on the bottom, clearanced and reworked Farmall H, take out H and Allis 226 on top.

 

 

8" billet rod on left, reworked Farmall H on the right, notice the different cap angle used on the billet for added clearance.  The H rod is actually 7.85" long instead of the original 8" length.  Both use a .990" pin.  I have the billet rod set up to take a H series Cleveite berring for a 2" Chevy crankpin.  There's a huge selection of berrings available to interchange for the billet rod weather you want a soft or hard berring, coated, etc.

 

 

 

 

 

 

I know that when you send a set of rods for a 426 or a 301 to max Simpson, he puts the big end of the rod in a press and actually squashes the round hole into an oval - slightly. This sounds a little crude, but he obviously has it down to a science as far as how far to go. This is all prior to the heat treat process. Then when he gets the rods back from heat treat, the big ends are very close to being round for less machine work and material removed.

 

Ed, I just have a friend do any heat treating, he's got a large manufacturing business in town so with a scrap part for a test piece one can get the heat treat right before wrecking good parts.  Nitrading, heat treateing, EDM machine, it's nice to have friends like that.   Just buy a $6500 set of rods from Hyper..... they'll hold up just fine and it's as easy as makeing a phone call.  Though it's probably more sensable to spend a couple hundred bucks on yours.  I've seen hardened rods hold up fine, and I've seen billet ones break.  A little thought and sensable design into the rest of the engine sure help with one's final outcome.

LOL