LarryB340
Well-Known Member
Look at the rod parting line on the top rod and the one on the bottom, is the one with the narrow parting line cast, or forged? They all have the same numbers on them, but this one looks different, any idea why?
Connecting rod, this one forged or not?
- Thread starter LarryB340
- Start date
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Just looks like the parting line was ground down on one and not the other. On rods that have been properly prepped, the line is completely smoothed with a belt sander to eliminate any stress points on the surface. Most all connecting rods were forged. The "Cracked" connecting rods of today are powdered iron. Cheap to make and not very strong.
LarryB340
Well-Known Member
All of the other 7 rods look the same, ground off parting line, all the rods were stamped 1 through 8 except number 6, I believe this is number 3 with the narrow line. I was just concerned about it. Want this 340 build to be right.
Did you the rotating assembly balanced ? That would be the best way to increase performance and durability.
LarryB340
Well-Known Member
Oh, yeah, it's internally balanced, I have an awesome machinist, Brad Howard in Gainesville Ga. He did a great job on everything.
LarryB340
Well-Known Member
Like I was saying, all the identifying numbers on all 8 rods are the same, but this is the only one that looks different. Think I should be looking for another rod?
pishta
I know I'm right....
all LA OEM rods are forged
LarryB340
Well-Known Member
Anybody got 1 for sale, 340 full float forged, or can point me in the right direction, I don't want to run this rod.
Back in Time
Well-Known Member
If he's that good why not take his advise.He and you are the only ones that put an actual eyeball on it.
LarryB340
Well-Known Member
Gonna do just that, got a buddy that has 6 340 rods laying around, I'll take the bobweight card and a couple of the rods to the machine shop so it can be balanced with the rest.
69_340_GTS
Well-Known Member
If the rotating parts are already balanced, changing that rod will most likely require a re-balancing job. Also, there is no such thing as a cast steel connecting rod for a 340 Mopar. Matter of fact I'm about 99% certain Mopar never used cast rods in any hi-po V8 engines. Unlike GM, where cast rods could be found in Buicks and Pontiacs.
Here is some useful info from "Enginebuildermag.com":
Connecting rods
Chrysler small block connecting rods are essentially
all the same. And, Mopar connecting rods do have a good bit of
integrity. All are forged, but the 340 rods (p/n 2899495) are
bigger and stronger than their 273/318 counterparts (p/n 2406785).
Both part numbers have full-floating wrist pins. The 360 four-barrel
rod (p/n 3751015) is also a heavy duty forging, but has a pressed
pin. All small block rods have a 6.123" center-to-center
length, but 1974 and later 318 and 360 rods are of the pressed
pin design.
Here is some useful info from "Enginebuildermag.com":
Connecting rods
Chrysler small block connecting rods are essentially
all the same. And, Mopar connecting rods do have a good bit of
integrity. All are forged, but the 340 rods (p/n 2899495) are
bigger and stronger than their 273/318 counterparts (p/n 2406785).
Both part numbers have full-floating wrist pins. The 360 four-barrel
rod (p/n 3751015) is also a heavy duty forging, but has a pressed
pin. All small block rods have a 6.123" center-to-center
length, but 1974 and later 318 and 360 rods are of the pressed
pin design.
LarryB340
Well-Known Member
Thanks for the info I'll have to take a closer look at the part numbers on the rods. Don't see why the whole *** would have to be balanced again as long as I could come up with a rod that could be balanced the same as the others, big end, small end and overall weight, I have access to 6 rods, surely I would be lucky enough that one of them would work.
Not only that, but if the engine is balanced with that rod now, it will have to be rebalanced all over again with a different rod.
Because like someone else has pointed out, that rod is likely an early 237/318 rod. The rest of those rods have had to lose some serious weight somewhere to become as light as that one, because there is a huge difference in weight from the early rods to the later. I am not sure I would even trust that entire set. I would do one of two things were that engine mine. Either leave well enough alone and run it or pull it and put a brand NEW set of rods in it and have it rebalanced, IF it bothered me that much.....and it probably wouldn't.
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LarryB340
Well-Known Member
O.k.so I will pull that rod and piston out tonight to get a good look at it, if it is the correct part number for a 340 rod, I'll just go with it. The rod big ends came out to 507.50 grams, little end 241.00 grams, overall is 748.50 grams, in your opinion is that light?
Back in Time
Well-Known Member
Just so you know..we're not trying to spend your money for you but you asked for advise and that's what is out there...Note... RRR may be a little ruff around the edges but he know what he is talking about.
LarryB340
Well-Known Member
Believe me I appreciate all the advise I got here, I was not trying to be a smart *** and did not feel like anyone was being a smart *** to me. Just want this motor to come out right and be solid, my quest about if the rod weight sounded light was an honest one and I have since found the information I was looking for on rod weight. Thanks to everyone here on this matter
Is the rod weight light in comparison to what? It's heavy as hell compared to some things and light as a sumbitch compared to others.
Where was I rough around the edges here? I think you need a safe space and a security blanket. lol
LarryB340
Well-Known Member
Compared to a new rod. The info I found on a stock 340 rod tells me that mine lost around 10 grams when they were balanced.
Compared to WHICH new rod? There hasn't been a 340 rod made in a long time.
I wouldn't get real caught up in weight. I think it's a waste of time for all but the most raciest of builds. I think a lot of folks make much ado about nothing there. I cannot count the number of badass small blocks I've seen at the track that had nothing but the stock rods......and a lot weren't even balanced. ...and I'm talkin about stock eliminator record breakers. Not backyard builds.
Then by stark comparison, I've seen some of the most cried over, high dollar Nth degree builds blow slap the FARK up on the first run.
IMO, as long as everything is balanced as an assembly, it's probably ok. But as I said, if you change that one rod............
It's kinda a downhill slope.
LarryB340
Well-Known Member
Not talking about a new rod, but when they were new. Stock rod. I'm going to pull the piston and rod so I can get a good look at the part number, my old fart eyes can't make it out while it in the block, if the part number is correct, I'm good, if not I'll decide what I want to do, I feel like a dumb *** for not checking things better before assembly. I doubt if this engine will ever see a race track except maybe to get an idea of 1/4 mile e.t. and speed. These Chevy guys have got it made, they ruin a block and run to "pull a part" for another, 340 blocks are kinda hard to come by. Thanks for your input, I really do appreciate it.
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