340 stock rods vs eagle rods

-
M

mad dog

Well-Known Member
Joined
Dec 25, 2013
Messages
818
Reaction score
654
Location
ct
good morning, im just a novice mopar guy and not overly technical when it comes to engine building so id like to ask some opinions before i proceed.
Im having my 340 machined and rebuilt by a reputable mopar shop, its basically a stockish build, I had Oregon regrind me a 68 4-speed cam, i have X heads that are getting new everything and some clean up where necessary, 30 over with new pistons, im guessing around 10-1 compression when finished.
The shop owner called me yesterday and recommended to me that instead of re-conditioning my rods which would cost me around $800 he suggested a set from Eagle, he said that they will be just as good for my application and lighter and it would be half the expense, my question to you experts....
Is he making a good recommendation?
Is he being lazy and doesnt want to do the extra work?
he has built 2 engines for me so far and all have been good.
I kinda wanted to use all stock parts but the idea of saving $500 is enticing.
thanks for reading...Rich
 
That's pretty expensive to recondition your stock rods. The Eagle rods would definitely work well for your build. Being that there lighter than the stock rods you should have the rotating assembly balanced. I have the Eagle rods in my 70 340 Duster drag car and have had no problems with them. 65
 
I don't know what's currently normal for rebuilding OEM rods but $800.00 seems like a lot. But Summit does sell aftermarket I beam rods for a little over 400.00. Not sure if Eagle or OEM rods are stronger but saving money is a good incentive if reliability isn't compromised. Some people simply do not like Eagle SIR rods after some had issues with them years ago, possibly with strokers.

Personally I like the Scat I-bean rods which are stronger, forged from better 4340 material and only slightly heavier and slightly more expensive than the 5140 Eagle SIR forgings. i tend to lean towards things being a little better than they have to be.

To save a few bucks over Scat, I believe the Summit brand of I-beam rods are made by Scat.
 
mad dog said:
good morning, im just a novice mopar guy and not overly technical when it comes to engine building so id like to ask some opinions before i proceed.
Im having my 340 machined and rebuilt by a reputable mopar shop, its basically a stockish build, I had Oregon regrind me a 68 4-speed cam, i have X heads that are getting new everything and some clean up where necessary, 30 over with new pistons, im guessing around 10-1 compression when finished.
The shop owner called me yesterday and recommended to me that instead of re-conditioning my rods which would cost me around $800 he suggested a set from Eagle, he said that they will be just as good for my application and lighter and it would be half the expense, my question to you experts....
Is he making a good recommendation?
Is he being lazy and doesnt want to do the extra work?
he has built 2 engines for me so far and all have been good.
I kinda wanted to use all stock parts but the idea of saving $500 is enticing.
thanks for reading...Rich
Click to expand...
$800 sounds stupid, or he does not do them. If I were to buy aftermarket, which I rarely do, it would be Molnar.
 
I agree, $800 seems like a lot of money, he does condition rods but he says after all he has to do to them i would be better off with eagle rods and i would save some cash.
Remember guys this was supposed to be a stock type build , not a race car by any stretch so im thinking the eagle rods would live nicely in my 340, the car is just a weekend cruiser.
He said my original rods were pretty rusty and not in the greatest shape. I really think hes not trying to work on my stock rods and would prefer installing and balancing new shiny stuff.
 
You just have to remember when buying rods to get the ones that you need. Some used press fit and some used floated pins.

If it has a bronze bushing in the small end like all Molnar Technologies connecting rods have then they require pistons that float and use Spirolox to hold the pins in the pistons.

In addition to the aftermarket rods using far superior materials (4340 steel) they also have larger cap screw rod bolts. I sell a lot of AMC connecting rods and the aftermarket Molnar

rods are almost 200 grams lighter than the OEM 401 rods while being several times stronger. This is a win win for any engine combination including even stock builds as it will allow

the engine to make revolutions at a much quicker rate. You can't go wrong with upgraded rods.

Tom
 
If he's including new rod bolts, new small end bushings, resizing and weight matching them all, I can see $800. I agree. I think he's giving you good advice.
 
thank you all for your advice, i really do appreciate all the feed back... i can provide more info on the rods after i visit him this week, i will also provide a dyno sheet when all is said and done, this 340 is based on the 68 340 specs or at least it was until the addition of the aftermarket rods...Rich
 
We just put Scat rods in my 340 build. Combined with a much lighter Icon piston we reduced the reciprocating weight by over 300 grams per cylinder. That’s free horsepower, and we ended up at over 460hp on the dyno with no tuning and a pretty mild cam. I don’t think I’ll ever be able to use stock rods and pistons again even though there’s really nothing wrong with them. The aftermarket stuff just gives very real benefits at a good price.
 
mad dog said:
good morning, im just a novice mopar guy and not overly technical when it comes to engine building so id like to ask some opinions before i proceed.
Im having my 340 machined and rebuilt by a reputable mopar shop, its basically a stockish build, I had Oregon regrind me a 68 4-speed cam, i have X heads that are getting new everything and some clean up where necessary, 30 over with new pistons, im guessing around 10-1 compression when finished.
The shop owner called me yesterday and recommended to me that instead of re-conditioning my rods which would cost me around $800 he suggested a set from Eagle, he said that they will be just as good for my application and lighter and it would be half the expense, my question to you experts....
Is he making a good recommendation?
Is he being lazy and doesnt want to do the extra work?
he has built 2 engines for me so far and all have been good.
I kinda wanted to use all stock parts but the idea of saving $500 is enticing.
thanks for reading...Rich
Click to expand...

Many of the aftermarket rods do not have oil squirt holes which oil the bore... I prefer to have oil squirt holes to keep the cylinders lubed good... I like to have the stock rods reconditioned with new bolts...

Then make sure that you get rod bearings with the notch for the squirt hole as some of them eliminated them also...

If you don't care about oil squirt holes and extra oil on the bore, then go aftermarket if you want...
 
Typically you need rod bolts and resize the big ends. I add a pin oiling hole. Stock 340 rods are bushed and plenty strong enough for a stock 340 build. It's not like they are Chevy rods. My machinist said 340 rods would hold up to a supercharger. Just had a set of early Hemi rods done last year, I'll look what I paid for rod rework. As for the OP, do what you feel is best and most cost effective for you.
 
Last edited:
If his engine builder can't or won't rebuild the OEM rods for less than Eagle or Scat I-beams, there's nothing to debate, especially with the street application and it's not constantly abused.

FWIW, the lighter the piston, the better it is for the rods and everything else. SRP & Probe had some pretty light pistons at a reasonable price. Not sure if they are still made or affordable anymore.
 
Well now Krazycuda has me thinking about oiling holes, i would think thats pretty important.
I will ask the machinest about that. Im looking for reliability and longevity with this build.
This is definetly a street build with little or no abuse, my friends say i drive like a little old lady...lol
 
Your machinist is smoking crack if he expects to get 800 to rebuild stock rods. I charge 20 each to install ARP bolts, cut cap and rod and resize. It's not hard, I do jeep 4.0 rods like that all the time, probably did 48 of them last month alone
 
The issue with the Eagle products is they are finished in China, packaged, and sent to the USA to be sold as is.

Scat rods are finished in China and then inspected in the USA

Molnar rods are made in China, honed by Molnar in Michigan, inspected, boxed, and then ready to ship.

Now ask yourself is the low cost Eagle products really a bargain if you have to remachine them?

Tom
 
i agree, he was pushing me to go aftermarket, he said a lot of work goes into rebuilding them, checking for cracks, shot peening,balancing ect.
this shop is known to be pricey but deliver a weel built engine
 

mad dog said:
i agree, he was pushing me to go aftermarket, he said a lot of work goes into rebuilding them, checking for cracks, shot peening,balancing ect.
this shop is known to be pricey but deliver a weel built engine
Click to expand...

If you are going to the trouble to rebuild an engine that you're pouring good money into then spending $705 on aftermarket vs $800 for rebuilding 50-year old rods is a no brainer.

What you'll have in the end will be a far better engine with performance advantages, and the peace of mind that an old OEM rod doesn't break a beam totaling out the engine.

Tom
 
Last edited:
You must log in or register to reply here.
-
Back
Top Bottom