Is it true that the connecting rods for a 1973 and newer 318 are a better rod than the pre'73's? If I was to buy new connecting rods, would a "I" beam connecting rod be strong enough even if I wanted to up the power level later on
318 connecting rods
- Thread starter Dan the man
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Make sure you order rods for a 340 if I beam they have a stronger heavier beam then a 318. I always bought h beams but just my preference.
Look at the forging number. That will tell you they are the same forging as later 340's and 360's. All Mopars had very good rods. I don't think it is worth swapping them. Racers, as I understand, even used 273/318 rods to lighten the rotating assy. Just make sure the big end is within spec and use good rod bolts. Floating pins are a nice to have.
Budget Racers use them but change the rods every season or so. For light weight $1500 aluminum is the stronger replacement. $5000 Titanium are the upgrade from there. Break a rod and you'll usually take out the whole engine. The weak link of most bottom ends is connecting rod . The bottom end is not a place to go drastically cheap. Just my opinion and everyone has a different outlook on this.
All depends on what you are doing. Sprint car or unlimited budget, go with titanium. Aluminum, I would never use. A guy building a nice street performance engine, I have no problem running stock Mopar rods. We all have to do what we need to to sleep at night. One thing is for sure, If a rod comes apart, you will probably need everything.
Rat Bastid
Dunamis Metron
Ti rods are a bigger PITA then they are worth. Ti isn’t a very good materiel for a connecting rod. In fact, before NHRA dictated connecting rod weight no one was using Ti. There was a guy making composite rods. Not only were they ultra light and mega strong, they didn’t need a rod bearing!
NHRA hates innovation so they killed that rod with a weight rule. I forget what year that was, but it had to be close to 20 years ago. Had NHRA not ruled them out of existence that technology would be drifting down to us mere mortals. How cool would it be to not run a rod bearing? Think of the weight you’d save just with that alone.
NHRA hates innovation so they killed that rod with a weight rule. I forget what year that was, but it had to be close to 20 years ago. Had NHRA not ruled them out of existence that technology would be drifting down to us mere mortals. How cool would it be to not run a rod bearing? Think of the weight you’d save just with that alone.
Carbon Fiber?
What kind of engine are you building?
Nitro engines and alcohol engines run aluminum rods . They have different characteristics . Alcohol 10,000 rpms top fuel 7,900 rpm's. So never put down the use of aluminum. I just ordered GRP for our small block. The rod on he left is the nitro rod on right methanol. You can see the material cut from the beam and big end on the alcohol rod and The open rod bolt to measure stretch.
I bought rods for my street motor . I bought H beam
Your right it is all about money. But you only get what you pay for. If your going to spend money start at the foundation. You don't build a 3 story steel building on a cinder block foundation. I would not use 318 rods on anything for street performance if I want durability. I would use at least a 340 360 bushed rod. with floating pins That's Just me.
dano
Evil Handy Man
Up the power to what and what RPM? I think that will help narrow down your selection.
I've known guys to spin stock rods for years at 6500-7000 rpms. Usually a main bearing would spin before a rod gave way.
pishta
I know I'm right....
AL rods have a malleability that iron rods dont have. Think of it as a very slight shock absorber for your crankshaft. They can be alloyed to run on the street for some time now (Bill Miller rods). With I and H beam rods available for under $500, I think that is a wise foundation with a forged crank. I would go farther and say the weak link in the bottom end is the rod bolts themselves. I think the one upgrade for the bare bone budget build is at least 180,000 psi rod bolts. ARP, Milodon, Pioneer, etc.
as for composite rods...Naimo tried raising crowd sourced funding for them in 2017, this is what I found...CLOSED. Maybe the crowd source funding didn't go ever well.
LS Carbon Fiber Connecting Rods: Naimo Composites
Discover the Future: Lighter, Faster, Stronger!
Chris Naimo
1 Campaign |
Roxbury, NJ, United States
$125 USD 2 backers
0% of $175,000 Fixed Goal
as for composite rods...Naimo tried raising crowd sourced funding for them in 2017, this is what I found...CLOSED. Maybe the crowd source funding didn't go ever well.
LS Carbon Fiber Connecting Rods: Naimo Composites
Discover the Future: Lighter, Faster, Stronger!
Chris Naimo
1 Campaign |
Roxbury, NJ, United States
$125 USD 2 backers
0% of $175,000 Fixed Goal
All correct. Most of us will never need an aluminum rod, even though some racers run them by choice for NA use. I’ve seen more than one stroker B or RB race engine run them.back in the 1974 direct connection white book, Chrysler offered both factory style small block rods forged from 4340 chromoly instead of the regular 1053 steel. I know there has been a lot of mixed reviews on them, but I’ve seen the Eagle cheapo I beam chromoly rods go through some incredible abuse in a 318 stroker with zero problems. That motor flaked the moly off the rings and wiped the cam after prolonged detonation while towing on a tank of bad gas but the rods still magnafluxed good. I would run them without a second thought.
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It is all about intended usage. 318 and 340/360 use the same material and forging. What do you think is different, other than a bronze bushing on the small end? That is also what I prefer, but I was building engines in the 70's and 80's and had the pick of whatever I wanted. No shame in pressed pins. The main thing for a rod is the large bore diameter. My context is general street performance. A strong engine built to last for over 100,000 miles and spin 7.000 rpm max. Never would I use aluminum rods on the street. Of course I am not talking racing engines of any type. I don't even post in the racing forums.
I have a set of those, maybe I'll use them some day. If my stock rods ever give up. But I feel I'm running out of days...
From all this guys threads he created, if he ever buys a car, for what seems to be his intended use he in nowise will outgrow the stock rods.
Scat I-beams...they are inexpensive, light weight, and can handle quite a bit of HP (I believe they are rated for 650hp), and they come with ARP rod bolts. I have them in my low 10 second car and they work just fine.
That's why I asked in post #8. This thread has gone off the rails. It doesn't help that the op started this thread at 2 am and cant/didn't hang around to answer some questions.
They are 340 rods, same forging number as I recall. But man, they are hard.
This right here ^^^^^^
I am having a discussion in another thread about selling and buying in non sale threads. Do yourself a favor if you are interested, send the member a pm instead of posting it in a thread.
Lay one next to a stock sbc rod that the lowbuck sbc guys spin pretty hard, and no one would doubt their strength.
Just curious, what does the weight compared to an equivalent 1053 rod?
Same in my 50 year old Lawn Boy push mower. It even has needle roller bearings with a steel liner and a hardened forged crank. But I think we are talking different power levels here.
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