I could weigh one, but they should be about the same. Alloys, do not make up much of the steel volume.
318 connecting rods
- Thread starter Dan the man
- Start date
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I could weigh one, but they should be about the same. Alloys, do not make up much of the steel volume.
The {273/318} Connecting Rod (#1618699)
* 726 Grams
The {late-318 and 340/360} Connecting Rod
* 758 Grams
Piston Pin (For Both Connecting Rods)
* 154 Grams
All 'LA Engine' Connecting Rods were 'Forged Steel'
Forging Numbers
* 1964-1969 {273}.........1618699 - Full-Floating
* 1968-1969 {318}.........1618699 - Full-Floating
* 1970-1971 {318}.........2406782 - Full-Floating
* 1972-1973 {318}.........2899062 - Full-Floating
* 1974-1975 {318}.........2899063 - Pressed-Pin
* 1976-1986 {318}.........3418645 - Pressed-Pin
* 1968-1973 {340}.........2899496 - Full Floating
* 1971-1974 {360}.........2899062 - Pressed-Pin
* 1974-1975 {360 HP}.....3418645 - Pressed-Pin
* 1976-1980 {360}.........3418645 - Pressed-Pin
No mention about the heavy pin for the 273 applications.
* 726 Grams
The {late-318 and 340/360} Connecting Rod
* 758 Grams
Piston Pin (For Both Connecting Rods)
* 154 Grams
All 'LA Engine' Connecting Rods were 'Forged Steel'
Forging Numbers
* 1964-1969 {273}.........1618699 - Full-Floating
* 1968-1969 {318}.........1618699 - Full-Floating
* 1970-1971 {318}.........2406782 - Full-Floating
* 1972-1973 {318}.........2899062 - Full-Floating
* 1974-1975 {318}.........2899063 - Pressed-Pin
* 1976-1986 {318}.........3418645 - Pressed-Pin
* 1968-1973 {340}.........2899496 - Full Floating
* 1971-1974 {360}.........2899062 - Pressed-Pin
* 1974-1975 {360 HP}.....3418645 - Pressed-Pin
* 1976-1980 {360}.........3418645 - Pressed-Pin
No mention about the heavy pin for the 273 applications.
Rat Bastid
Dunamis Metron
No, I forget how he was doing it. I’ve only seen pictures of them. I know he started making them again because I saw it on yellowbullet but I haven’t seen anything after that.
They weren’t CF but they were sweet.
The later 340's also used the forging #645 rods with bushed small ends. I have the different 273 pin weights, 2 barrel and 4 barrel. The 273 pins are also shorter. Some time today, I'll measure the 4340 rods.
Definitely so. If the 340/360 style rod is any lighter than the stock rod, it would be because they were able to reduce the amount of material in the body of the rod with the selection of the higher strength alloy. I’m going to use a set of 273/318 bushed rods in an upcoming project. Coincidentally, my machine shop operator claims that for 90% of the street builds, the stock Chrysler rod bolts are more than adequate. Chrysler learned quite a few things about aerospace grade fastener materials over in their missile and space division. Grade 10 fastener markings are commonplace on oil pump and cam retainer bolts.
All I can add here is, I've seen precious few broken connecting rods. More aftermarket than factory and the factory ones always caused by "something else" like a broken rod bolt or "something" that just got in the way. I've never simply seen a factory rod "just break".
Now, I'm SURE the forum heroes will line up to say they have. That doesn't mean you need to buy into it. I think the fact is, very few stock factory LA rods just "let go".
Now, I'm SURE the forum heroes will line up to say they have. That doesn't mean you need to buy into it. I think the fact is, very few stock factory LA rods just "let go".
Maybe a polymer, similar to Schubeck lifters?
They look the same as stock. I'll take pictures later today.
A good reference for comparison is to take a standard big block chevy rod with 3/8 bolts and place it side to side with a 318 rod. There’s not as much of difference as you would expect to see there.
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By the same token, place that same big block Chevy rod next to a 440 six pack rod. LMAO
Lolol! I thought that a Hemi rod was the be all-end all of connecting rod mass. But then I saw one of the Hemi NASCAR rods with the 1/2 inch SPS multi phase bolts in person. I’ve handled lighter boat anchors!
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318 rods have a totally different beam size. 318's are tooth picks compared to 340-360 340's are full floating pins 360's are pressed pins . I have a **** load of 340 rods and 340 forged cranks. all taken from good engines switched to strokers. If using the larger rods Balancing is closer with the forged crank due to the journals being drilled. My son does balancing but the pistons , rings , bearings and pins must be sent. He also reconditions the rods
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Let's pay attention here.
Let me be clear. My DC 4340 rods are not for sale. I am only giving information on something I have, and can shed a little light on someones curiosity.
273 2 barrel piston pins weigh 221.5 grams.
273 4 barrel piston pins weigh 183.5 grams
273 custom Trend piston pins weigh 143.1 grams
Rat Bastid
Dunamis Metron
Ok...I dug around and found out the name of them. The are Jager rods. You should be able to Google that name and find them. The were composite metal matrix of something. I need to do more research but I do know they were running them without rod bearings. That means you can make the crank lighter. A lighter crank can run more rpm. More rpm is more hp. And NHRA doesn’t want that.
Dan the man
Well-Known Member
A warmed up daily driver
Stock 273/318 rods will be fine.
You oftentimes see manufacturers give rods a horsepower rating, and that may apply for cyclic beam loading. But I’ve never bought into it as an accurate means of rating. Piston mass and stroke are the greater factors. Steel, like most other solids, is much stronger in compression than in tension. So the piston pulling against the rod and angular thrust loads impact rod life (especially the bolts!) more than the vertical thrust that happens in the first 45 degrees of crank rotation from TDC power stroke. Of course, it’s more viable in the case of supercharging or alcohol usage. And if you’re burning nitro, you’re foolish if you don’t have aluminum rods. But for 99% of us here, the hp rating of a rod is less meaningful than how strong the bolts are that keep them together at high rpm.
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Just like that.
Everybody always hollers about light this and light that. Heavy stuff has a place. All the mud boggin boys I know run heavy stuff. They say it gives more momentum. Must be somethin to it, because the ones that say that always win.
P3690641 Connecting Rods 775.4 grams, polished beams, pin oiling hole, SPS rod bolts and nuts, notice the dimples for rod stretch measurements. Notice the 3418645 forging number.
Stock 340 rod and 2 barrel piston for the 340 I'm building now. Notice the DC rod bolts with the dimples for taking stretch measurements and the same 3418645 forging number.
K.O. SWINGER
Meeting in the alley since 1976
Also when you combine the lighter Pistons that are pretty much commonplace now it drastically reduces the load on the connecting rod. I did a thread about a year ago rod breakers wanted which confirmed my belief that very few I mean very few HD 340 rods or small block Mopar rods at all broke from normal abuse. Almost all were due to other catastrophic failures of the motor which put excessive load on the rod causing it to fail. I've run HD 340 rods for 40 years and never had a failure with many RPM sweeps over 8000 RPMs due to miss shifts . But that being said new quality rods are always a great piece of mind if you're going through your motor.With top quality rod bolts being a must because they are definitely the weak point.
Contrast with the 273 rod forging number 2406782 and the 340 3418645 forging number. The 273 rod is what class racers used to use and others in 340's to lighten up the rotating assy. I've seen later 318's and 360's with the unbushed 3418645 forging number also.
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