con rod design

Alan Jackson /

are con rods with no lubrication holes/slots at all to be avoided?

a piaggio/vespa pk50/ con rod kit might fit my project engine but unless i pay silly money for a mazzucchell with postage (im in uk) most ive seen have no lube holes.

i once tried drilling a hole for the small end but gave up after numerous blunt drills

i know a machine shop could do something

Re: con rod design

Luke Stroehlein /

I put a hole in the top of my con rod with a diamond bit in a dremel.

Re: con rod design

The crank I bought, with needle bearings, didn’t have an oil hole.

I assumed this was because lube gets in through the gaps between the rollers.

Is that a correct assumption? Or should I pull the piston off and rub a diamond hole in it?

Re: con rod design

Conrods are case hardened, so they will eat through regular drill bits, they will also soften when reworked so you would want to get them hardened again or shot peened at least.

Re: con rod design

Luke Stroehlein /

> Rebel Moby Wrote:

> -------------------------------------------------------

> Conrods are case hardened, so they will eat through regular drill bits,

> they will also soften when reworked so you would want to get them

> hardened again or shot peened at least.

Happened to me once and now I can't have kids

Re: con rod design

You can get things called HiRoc and HiTough Drills.. they are solid carbide and can drill up to 60+ HRC and wont leave much if any of a heat affected zone. Not cheap though. I drill holes in ball bearings with them quite often.

You can try with a masonry bit from the hardware store on the cheap.. it may/may not work but you could give it a shot.

It depends what you are doing lube will still get to the bearings on the sides of the rod, if you are revving 12K+ then yeah the center holes on the small end and the big slots on the bottom end help promote lubrication at the center.

If it

Re: con rod design

Use a little diamond dremel bit to start the hole or get past the case hardening. then use a 1/8” cobalt bit to finish. use a small diamond bit to deburr. I’ve done it before with good results.

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