Stock 340 rod opinions

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Duane

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My 340 w2 motor with my newly ported heads is headed for the high ten second bracket et.
I am contemplating a change of my stock 69 340 rods with arp bolts to an aftermarket 4340 rod for durability concerns. ( eagle H beam is my first choice )
Does anyone think my stock rods with the arp bolts are adequate or do you agree with my contemplated rod change. The motor has already run 11.20 in the quarter in a 1968 dart at about 3100 pounds and should run faster with my ported heads.
This is not a stroker motor and I estimate it will need to rev to 7400 trap rpm.
What are your opinions please. I have been advised by some that the stock rods will not cut it and others have said the steel from stock rods of this year had superior steel to newer aftermarket rods. The stock rods had been re bushed and resized with arp 2000 bolts.
Thanks

Duane
 
How heavy is the piston on the end of the rod?

at 7400 rpm I would go with the newer 4340 rod....
 
Didn't we JUST have a thread about this?
 
66fs said:
I always heard 7,000 RPM was the changeover point.
Click to expand...

let see...shift at 6300 rpm...goes thru the trap at 6300...bang...stroke rod broke...i guess that rod did not see your post...piston only weight 502 grams.....hell of lot less then stock 340 piston...

if you are going to turn some rpm....get light...pistons and rods...

my answer...use what ever lets you sleep at night...
 
That's alotta RPM's on a OE rod IMHFO. The OE rods are very good until a point. Your passing the point. Step up and step up well.
 
I have read some recent performance books that make rod recommendations based on intended rpm and others that recommend by horsepower rating. For example the recent publication " how to build big inch mopar small blocks " recommends an aftermarket 4340 rod after 450 horsepower. It is assumed that because of the large displacement stroker motor that the rpm will only be in the 6000 rpm range. Not a lot of rpm , but I am certain that I am already over the 450 horsepower mark with stock w2 heads and .650 lift roller.
My apologies if I have raised an overly brought up question. I don,t post on here very much and was just looking for some quick opinions. The consensus seems to be that My rod purchase is justified

Thanks for the replies

Duane
 
I make the recommendation based on not what has been done but what I have seen happen at this point. If you deburred, smoothed the rod, shot peened, resized, rebalanced etc.... and gave it new HD bolts, is say it'll be OK. Though by the , the monies spent would have gotten you a much much better rod.

Due to my grey matter getting.. er.. Grey-er... What is the metal of the OE rod.
 
rumblefish360 said:
I make the recommendation based on not what has been done but what I have seen happen at this point. If you deburred, smoothed the rod, shot peened, resized, rebalanced etc.... and gave it new HD bolts, is say it'll be OK. Though by the , the monies spent would have gotten you a much much better rod.

Due to my grey matter getting.. er.. Grey-er... What is the metal of the OE rod.
Click to expand...

yeah i thought so too....beams polish..shot peened...small ends balanced..etc....new arp wave lock bolts...and one still snapped..
 
if you have a very large budget, call Callies have them make you a set of billet steel rods

then the crank or block will go first lol
 
70aarcuda said:
...i guess that rod did not see your post...

if you are going to turn some rpm....get light...pistons and rods...

my answer...use what ever lets you sleep at night...
Click to expand...

According to Ed Hamburger's catalog, a blueprinted stock 340 forging is good to 7,500 RPM. Heat treated, magnaflux, double shot peen, heavy duty pin bushings, careful blueprinting of big and small end, and high strength rod bolts. Not a cheap solution.

I was told that sprint cars were turning about 10,000 RPM, the only rods that were holding up were Carrillo's or custom Titanium.

I have run stock rods all my life, pulling to about 6,000 RPM regularly for years and have never broke one.

It all comes down to what you said, "use what ever lets you sleep at night".

Where did your rod break?
 
66fs said:
According to Ed Hamburger's catalog, a blueprinted stock 340 forging is good to 7,500 RPM. Heat treated, magnaflux, double shot peen, heavy duty pin bushings, careful blueprinting of big and small end, and high strength rod bolts. Not a cheap solution.

I was told that sprint cars were turning about 10,000 RPM, the only rods that were holding up were Carrillo's or custom Titanium.

I have run stock rods all my life, pulling to about 6,000 RPM regularly for years and have never broke one.

It all comes down to what you said, "use what ever lets you sleep at night".

Where did your rod break?
Click to expand...

In 30+ years of bracket racing I have broke 2 rods...but were stock rods....I got h beams in the 2 of the cars now....Scat I beam in the other..,,..the last one just a year ago.....nice set of rods prepared for SS engine...engine was being shifted at 6300 rpm yeah...

Ed Hamburger has been out of business for 20 years or so too...

I sleep well these days....but that might be the Sleep Number Bed...
 
Yeah, he dropped out quite a while back. He had a lot of information in the old Catalogs. He was not afraid to put numbers out there and back them up with experience. I know you are doing the same. Hope you are good to go for the next 30 years.
 
Lmao! Sleep number bed! That's freakin great!

I hear ya Tony on the rods. You can dump a lot on the stockers if you wanted to but end up no better than a good set of aftermarket rods at best. The metal has a life span. The rods are how old now???? Thinking they can last under race conditions is not a great thought IMO. Limited use, ehhh, OK I would guess, but I don't like to guess when I have a bunch of money ties up in An engine.

While you could find and prep low mileage OE rods, there use in my book isimited to the street, er, make that easy street. For the cost of a new set with there ability (according to there manufacturer) to withstand *** HP, it's worth the expense IMO.

Building a 500HP engine, get rods better than 500hp! It'll live air longer.
 
Thanks guys for your advice. I worked out a fair deal with my local machinist. He will get the sale on a new set of eagle "H" beams in exchange for a much better price for a crank polish and a partial rebalance as I will be using the same pistons. I have a few bucks in the w2 heads and a rod failure would be way more costly than a new set of rods.
I too felt I needed to upgrade the rods, but it is great to have the real world experience and advice of members on a forum like this for some reassurance.

Duane
 
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