How to build your own racing connecting rods?

[Dumpling]

What length were you being quoted on originally? 9" or 8.25"?

Isn't there some heat treatment/relieving done after machining the rods?

Seems like going cheap and dirty while everything else isn't.  JMO

[pbf777]

A wild thought: could an old radial aircraft engine...............

On the radial engines, while they do have long rods, they're only designed to run at 3500 RPM max. I'd imagine you'll be pushing your engine to 5500-6000 with a good bottom end. Well out of range of what radial engine rods are designed to run. I'd be surprised if you could find anything close to correct journal sizes anyway.

     Just a note:  Apparently we're not familiar with the general engineering format of the typical "radial" engine, as this consists of a 'master' rod upon which then the other 'link' rods are attached, this permitting all pistons and rods in a singular radial cylinder row to be attached to the single crankshaft throw.  This making some rather not compatible engineering for the typical V8 automotive engine format.         For a better description, with pictures just Google it!     

     Scott.

[frnkeore]

Isn't there some heat treatment/relieving done after machining the rods?

All aircraft quality, steel parts are usually, started with either annealed or normalized material, then rough out, sent for HT, then finished machined, MPI and then plated, if needed. I never made any that plating, wasn't a spec.

[Royce]

Joel you might check with a materials engineer to see what kind of strength you need then select your material and dimensions..I think Bill Connely might be of some help there... Ted Eaton had Cunningham do a custom set of rods with offset caps after checking with several other rod mfg who really did not want the job...  Titanium?  I think if you cnc your own you are still looking at getting the proper heat treat and stress relief..  Check some Mercury Marine powerboat racing engines.. They have some big cubic inch stuff that would probably have tall decks and long strokes

[Royce]

Another thought.. Pulling tractors.. Those diesels have some honking long rods and I know the internals on some of those are all custom  If you can contact one of the pullers in super stock class they might be able to point you to a source they use..   But really, a guy who owns a Duesie should be able to swallow 800 per rod  LOL

[jayb]

That's right Royce, if he would just stop eating shrimp every night he could afford custom rods 

(Sorry, that was an inside joke...)

[cammerfe]

There can't possibly be anything wrong with a guy that wants shrimp regularly. I know a place that offers all you can eat...
But that's another story!

KS

[cjshaker]

Just a note:  Apparently we're not familiar with the general engineering format of the typical "radial" engine, as this consists of a 'master' rod upon which then the other 'link' rods are attached, this permitting all pistons and rods in a singular radial cylinder row to be attached to the single crankshaft throw.  This making some rather not compatible engineering for the typical V8 automotive engine format.         For a better description, with pictures just Google it!     

     Scott.

Gee, considering I'm a vintage war plane buff, and have flown in multiple radial engine planes, I didn't even stop to think that a radial engine was designed differently than a water cooled V8. Thanks for pointing that out. 

[winr1]

I over looked this  " This is for the blown 337 Lincoln flathead for land speed racing "

Since it will be blown, can the piston be below deck making the Comp height shorter ??

Also since the pistons need no valve reliefs the piston top can be only thick as it needs to be making it lighter

Have the pin bosses use a narrow wrist pin .... shorter skirt on non thrust side ..



What rpm will this turning if I may ask ??



Ricky.

[Barry_R]

R&R used to make custom steel rods, but I don't think they do them anymore.  Last set were closer to two grand than to one grand and it's been many years.

You could probably make something out of 3/4 plate, but it would take a couple of minutes on the mill...

[JERICOGTX]

But really, a guy who owns a Duesie should be able to swallow 800 per rod  LOL

I don't know... He keeps losing dinner bets to me... LOL.

[machoneman]

A wild thought: could an old radial aircraft engine...............

On the radial engines, while they do have long rods, they're only designed to run at 3500 RPM max. I'd imagine you'll be pushing your engine to 5500-6000 with a good bottom end. Well out of range of what radial engine rods are designed to run. I'd be surprised if you could find anything close to correct journal sizes anyway.

     Just a note:  Apparently we're not familiar with the general engineering format of the typical "radial" engine, as this consists of a 'master' rod upon which then the other 'link' rods are attached, this permitting all pistons and rods in a singular radial cylinder row to be attached to the single crankshaft throw.  This making some rather not compatible engineering for the typical V8 automotive engine format.         For a better description, with pictures just Google it!     

     Scott.

RPM limits are noted. Yet, having 'done' my share of radial engines, some rods potentially (not the master of course) could be used. Yet, I'd not want to test the rpm limits  of older design rods in my engines, just to be clear!

[BigBlueIron]

Good friend of mind builds tractor pulling engines. Makes his own rods, material is flame cut to a rough shape by a supplier and he does the rest in house. Not sure what the material is. I could ask if interested.

[Hemi Joel]

I over looked this  " This is for the blown 337 Lincoln flathead for land speed racing "

Since it will be blown, can the piston be below deck making the Comp height shorter ??

Also since the pistons need no valve reliefs the piston top can be only thick as it needs to be making it lighter

Have the pin bosses use a narrow wrist pin .... shorter skirt on non thrust side ..



What rpm will this turning if I may ask ??



Ricky.

We plan to run 6500 rpm.

[Hemi Joel]

We have our first draft of a rod. Now we need to have it analyzed. It is a stretched version of an Oliver BBC rod. Cam has it all in a cad file. He put an Oliver rod that we borrowed from JericoGTX in his coordinate measuring machine, then manipulated it to make it longer.