looking for a heavier rod than the diesel buda rod

Make it easy on yourself.....first, use the rods that are NOT rifile drilled for oil pressure to the piston pin bushing.....two, have your conn rods heat treated like the diesel superstockers used to do.....they won't bend anymore if done right.

There is no substitute for FORGED 4340, go big o

Mitch, Cyro is smoke and mirrors in my opinion for most alloy steels, good heat treat practices will yield excellent results and good grain structure without cryo treatment, but it is very important that the critical temper range be avoided for this type of part. Aluminum rods have a very short life span, I would not consider them for this application. I'm not sure who forged the Buda rods, but if they say Atlas on them, chances are that they are made form 1040 sbq forgings,  and the mechanical properties are limited, and re-heat-treating won't do much for them. I would persue a 4000 series alloy rod, preferably forged, but even a machined rod from the right material would do well for you.

Second the cryo, it doesnt do anything for a regular rod.  It might, and that is a big might help stabilize some types of steels after heat treat but the amounts shown to help are so minuscule it could be just natural variation in the material, not worth the money in my opinion.    

Here you go, straight out of Ford service info: Rod bearing I.D. 2.5005-2.5025, center to center 7.130, piston pin bushing I.D. 1.308-1.309.

Edited by Brian Jasper co. Ia - 04 Oct 2010 at 2:43pm

Brian Jasper co. Ia wrote: Here you go, straight out of Ford service info: Rod bearing I.D. 2.5005-2.5025, center to center 7.130, piston pin bushing I.D. 1.308-1.309. My Buda rods say "Atlas" on one side and Buda on the other. I thought Joe Mondello was known as Mr. Oldsmobile.

  the 7.3 rods out of the question crankpin to large . I really would like to stay with the 7 3/8 rod and 1.27 ratio . spent to much time on cams duration to change it to.

He was on Power Block last season. Sounded like he really knew what he was talking about.

mlpankey tried to put this in the
last post but it didn`t show up

http://www.standardcrankshaft.com
/connectingrodcatalog.html?sid=4272
B:-) Dnoym

I would just about bet that those Buda rods are nothing more than 1040 steel as I mentioned above, I sunk many dies for Atlas Drop Forge in a previous life, and rarely saw material spec.s for anything better than that. The standard order of the day was to forge, re-heat, hot trim, and quench in brine, followed by a tempering cycle, a full annneal, followed by a carefully controlled heat treatment may yield a stronger part, but don't waste the money to cryogenically treat them, a properly executed heat treatment of this steel will yield a 95% or better transformation to martensite, and the remaining 5% won't make it or break it for you.

I saw that 6.2 GM diesel has 2.25 big ends. Still too big? I tried finding specs on 5.9 Cummins, but only saw the small end listed as 1.5".

d17brown wrote: i use farmall 350 rods with 325 psi compression and no bending or breaking in 5 years

yes we didnt bend the c farmall rod either at a cylinder psi of 300 or so . I first thought with the other motor timing was what bent the first set . Timing could have started the buda rod to bend in the new motor when the gov weights blew . rpms went higher than timing was advanced for by being locked to total timming but its essentially locked to total timming also with a dizzy using mechanical advance because according to allis manuals the delco 111 dizzys advance should be all in at 800 rpms.i usually idle around the pulls at 1000 rpms to keep plugs cleaned.  cylinder pressure is in the 500 psi area. I am thinking its more a horsepower/rpm issue. with the rods seeing twice the rpms and hp they would have been engineered for in a 262.

Edited by mlpankey - 06 Oct 2010 at 11:30am