Advice on connecting rods
 

I'm in the process of planning a 400 build. Was planning on using the 5140 rods and then I ran across these:

http://www.ebay.com/itm/172485713396...%3AMEBIDX%3AIT

The price seems too good. Anyone know anything about these rods? Any good? Building a pretty tame street motor 9.5 compression, 60916 or 2802 cam.

Would be most likely better than the 1963-1965 Rubber Rods.
In a tame street motor they would be new and if the machining was properly done live as long as all of the rest of the Chinese import rods. Eagle, Manley, etc.

The steel used and the MACHINING make the difference.

This is a quality off shore connecting rod as the machining is very good:
http://www.molnartechnologies.com/

http://www.molnartechnologies.com/rods-dom-pontiac.html

Tom V.

H beam type Rods are in the least twice as strong as 5140 Rods even if they where of the same steel!
Just note that those H beam Rods require Pistons with floating pins most likely.

If your not looking to rev above 7K rpm with more than 4.21" stroke Crank then I have no issue with the 5140 Rods, but either way you may go get the big ends checked by a shop and buy a Rod bolt stretch gauge and get the rods set in the new motor the right way, not with a Torque Wrench!

FIFY.

H-beams tend to be twice as heavy as I-beams, too.






1. How are you planning to verify the quality of the steel used?
2. How are you planning to verify the quality of the heat-treatment?

That pretty-much means that you're likely only going to verify the machining, if that, and we've seen enormous problems with Chinese engine parts to date. I'll never understand the fascination with Communist products.

You know your right, now that I checked again H beam Rods are 3 times as strong as a I beam Rod unless we are talking top of the line Oliver Rods!

Where are u getting this info from???

"...H-beams tend to be twice as heavy as I-beams, too..."


I assume you guys are just joking with one another, since the Eagle H-beams are listed at only 760g.

"...The price seems too good. Anyone know anything about these rods? Any good?...


I'd go with RPM H-beams. They're $400 shipped, direct from RPM, and you can buy 'em for press-in pins, if you wanna use the SP L2262F forged pistons.

http://www.racingpartsmaximum.com/sa...elhbeam-2.html

Eagle H-beams are about $75 or so more. Don't know that they are any better than the RPM. But, I'm sure some of the engine builders have an opinion, one way or the other.

http://www.cnc-motorsports.com/eagle...ods-40480.html

https://www.nolimitmotorsport.com/prod/EGL-CRS6625PP3D

X 2.

I have no clue where that twice as heavy as an I-Beam rod came from but you should reinvestigate that deal. Unless you think that the fact the H-Beam rod has a different shape vs the I-beam rod therefore twice the weight is your thought. Doesn't work that way.

Tom V.

Hey Shurkey, at the risk of adding a little levity to this thread, what does FIFY mean? The only thing I could conjure up is Find Out For Yourself! Lol.
Thanks,
Tony

FIFY- Fixed It For Ya

I used these in my recent 495 cid 4.5 stroke build, albiet in 6.7 bbc length

I had no idea Molnar Technologies existed. Wise they produced a 4" stroke crank for the 3" main blocks.

Rule of thumb, not applicable in all cases:
H-beam rods weigh more than I-beam rods.

Depending on who you talk to, the "H" beam was a mistake, an "I" beam is either stronger at the same weight, or weighs less at the same strength. I'm not sure how I feel about this, considering that an "H" beam is just an "I" beam turned sideways. The "H" beam seems to have originated with Carillo, then monkey-see-monkey-do copied (some would say "knocked-off") by a plethora of other aftermarket manufacturers.

What I can tell you is that when it was my money, I bought "I" beams.

Go to Paul Spotts website and read what he says re the cheaper rods versus Eagle which is what he recommends. I personally would spend the extra $180 and get the better rods and not worry. Eagle isn't the only "better" rod obviously.

http://www.spottsperformance.com/

I agree. Tom Molnar worked at Oliver for many years before starting his own company. Very sharp guy and all machining done in house(he does a lot of it himself). My next motor will have his forged crank and rods in it. If anyone is skeptical, call the man.

Ive ran Eagle to 8300rpm with 4.250 stroke crank without issue. Very good rod for the price, fwiw currently i have an I-beam rod that's seen 9200rpm

Tom Molnar, as you posted, worked for Oliver Rods for years.
A bit more to the story: Molnar was actually more than just a worker, He was actually
the "go to guy" in the company for the technical knowledge. Oliver made fine rods for many years. Then they were purchased by a investment firm. Like many other firms (who were old school Hot Rod innovators) for big $$$$. Nice retirement package for the original owners. The way it should be after years of hard work.

But Tom Molnar likes the Hardware side of the game and making fine parts. He had the knowledge, just needed the resources to give it a shot to have his own company. So he is trying. Good rods are close in all dimensions for the machining. Molnar rods are, I am told by several people, very close in the machining for a set of the rods. Still off-shore steel but the rods are machined in house and you don't have the "wash-board road" deal that we had years ago with some of the cranks.

So not trying to sell his rods. Will let you do that Hooter. You bought a set. I have not.
I have all of the rods I need for my builds for several years.

One other comment: "considering that an "H" beam is just an "I" beam turned sideways" comment made by Schurkey. That is like saying that a Driver is the same thing as a 3 Iron, they are both Golf Clubs. In a simplistic sense that is true if you look at the rod or golf club.
Rod Designers Like Carrillo made their rod the way they did many years ago, FOR A REASON. Not wasting your time, or mine, trying to explain it to you, Schurkey, but the I-Beam design is good for certain applications and the H-Beam design is good for other applications. About as simple as I can make it. Carrillo Rads makes BOTH configurations, by the way. But back on the PY Guy looking for a decent rod. Molnar is one source, that does not cost $3,000 for a set of 8 rods. Machining DOES make a difference.

Tom V.

I-beam construction is stronger than H-beam. H-beam is lighter than I-beam. 4340 is stronger than 5140. Not sure where some of you guys get your info from. I forget which way it goes, but I-beam resists either twisting or bending better than H-beam, and H-beam resists the other better than I-beams. I balance a lot of connecting rods, and size for size, H-beam are always lighter than I-beam, unless you're talking one of those skimpy little SCAT I-beam rods for a SB Chevy. They are skinny, and wimpy. In the Pontiac world, the 5140 rods are in the 870 gram range[stock cast rod is 900 grams], while the H-beam is in the 800 range.