[GTO-relic]

Fireball Roberts set the pole for the 1963 Daytona 500 at a speed of 160.943 mph. This marked his third consecutive pole position at Daytona with a Pontiac.
The average speed for the 1963 Daytona 500 was 151.556 mph.
Pontiac 421 equipped cars finished 7th and 8th, ahead of Smokey Yunick's 9th place 427 Mystery Motor equipped car, who had defected from Pontiac to Chevy that year.
500 mile NASCAR race with average speed of 151mph, is a 3-1/2 hour race.
Using factory forged GM SD421 rods.
That requires sustained 6300rpm engine speeds for 3.5 hours.

Vintage forged, heat treated, USA-made connecting rods are not weak.

The SD455 rod is even stronger.

[Shiny]

Originally Posted by GTO-relic

This begs the question, whats the difference between SD421 4140 steel rods, and 58-62 370/389 1140 steel rods.

They are very close. There's some chromium, molybdenum, silicon added to the SD421 4140 rod. But they are within a whisker of each other.

SAE-AISI 1140 Steel vs. SAE-AISI 4140 Steel :: https://share.google/vGhyqtoh9sXnOeU4A

Generic answer you know: same carbon content so similar properties are possible. 4140 will be a LOT easier to harden and will be tougher. And you also know you will pay for that hardenability.

Another big difference is likely sulfur content. I think 1140 is typically re-sulferized to make it machine easy, but I'm no expert. Those sulfide inclusions are great for making chips on a mill but not so great for fatigue or even toughness.

Another possible difference may be in cleanliness. Just guessing, but I'd expect the cost of 4140 to also deliver more QA and less crap in the metal. This won't matter much for overall strength but could make a HUGE difference in fatigue performance.

Net: 1140 costs less to make and machine, may be good enough if part is never stressed above fatigue limit and the manufacturing process can consistently deliver enough strength through the part section. Pontiac and that vertically integrated world made it happen. IMO, 4140 would be a safer bet today to get the properties you want.

[PAUL K]

Lots of discussion on an already discussed subject .

Things change over time and folks form opinions from tales told over and over, whether those tales are true or false. A lot of folks shy away from wanting to use factory parts due to hearing the same story about one guy who actually broke a factory part retold thousands of times and being misrepresented as the information being first hand, second hand or even true at all.

I recently listed a 428 in the classified section that was built with a factory crank and SD-455 rods. More than one person was turned off by the cast crank or the "bound to break it you look at them wrong" SD rods. They would rather take their chances with a foreign made, mass produced part that needs to have all the dimensions checked, corrected if needed and then hope it was a good forging. Which most of the time they are. Personally knowing the history of the rods and crankshaft and the intended application I preferred to use the factory parts over the imported parts.

The issue I see nowadays is having an original part reconditioned to be the best it can. We used to send a lot of crankshafts to Crankshaft Specialties. They had an excellent program that would take our good known core and turn it into a top notch competitive part. They are no longer around.

We used to send a lot of rods to a company that did aircraft quality shot peening and within a couple of miles of the shot peen guys was a business that would heat treat our connecting rods and crankshafts. I had a crank guy that had more than forty years experience just grinding cranks. The shot peen company moved, the crank guy retired and the heat treat shop became extremely difficult to deal with.

Lack of convenient services makes the imported race parts more appealing.

[Shiny]

Originally Posted by Formulajones

There is a large misconception of what is Chinese and us made. Basically just because it says usa doesn't necessarily mean it's made in the usa. The majority still comes from China, only 1 or more processes are done in the US and using that loophole many claim USA made when in reality it came from China to start with. Not all companies are that way but the majority are so no matter how hard you try to keep everything USA made I guarantee there are Chinese parts mixed in whether someone wants to admit it or not. And all this complaining about China this or that is a mute point when I don't see anyone complain about the price.

But I don't care about any of that. There are plenty of excellent rod choices out there, we don't need to be sorting through 60 year old rods to put in engines that already cost $10-$15,0000 to build. Anyone that wants to do that is just a crazy person. And all the victories you speak of were again, 60+ years ago when you could buy the rods new. This ain't 1962 anymore last I checked. But hay if you want to source relics and then spend $100's on them to make them usable, no one is stopping you. We might think you're nuts but you're welcome to it

This all makes sense to me.

IMO, China isn't the problem. I view it as US companies compromising quality to get cheap material and parts. All that metallurgical QA GTO-relic describes can be done in China. But it costs money. If an aerospace company is buying metal or parts made in China or India, I suspect they get what they want and they pay for it. They aren't going to blindly buy stuff and hope it's good.

If, however, a US aftermarket company depends on low costs to stay in business, they have a hard time paying for QA.... especially on low-volume parts. Just my 2c. I think accountability got lost when manufacturing got farmed out. It's easy now to blame your quality and reliability issues on a supplier that you choose not to manage, then try to fix it by changing suppliers.

[Elarson]

People that I've known in the manufacturing businesses seem to agree:

If you have something made in China and the US company rides their *ss on quality control, material traceability, dimensional inspection, etc., you can get a good product.
If you throw a drawing over the proverbial wall and then sit back and wait for a box of parts to hit our shore, it's got high odds of being shortcutted crap.

Eric

[Shiny]

Nice summary!

[Formulajones]

Originally Posted by PAUL K

Lots of discussion on an already discussed subject .

Things change over time and folks form opinions from tales told over and over, whether those tales are true or false. A lot of folks shy away from wanting to use factory parts due to hearing the same story about one guy who actually broke a factory part retold thousands of times and being misrepresented as the information being first hand, second hand or even true at all.

I recently listed a 428 in the classified section that was built with a factory crank and SD-455 rods. More than one person was turned off by the cast crank or the "bound to break it you look at them wrong" SD rods. They would rather take their chances with a foreign made, mass produced part that needs to have all the dimensions checked, corrected if needed and then hope it was a good forging. Which most of the time they are. Personally knowing the history of the rods and crankshaft and the intended application I preferred to use the factory parts over the imported parts.

The issue I see nowadays is having an original part reconditioned to be the best it can. We used to send a lot of crankshafts to Crankshaft Specialties. They had an excellent program that would take our good known core and turn it into a top notch competitive part. They are no longer around.

We used to send a lot of rods to a company that did aircraft quality shot peening and within a couple of miles of the shot peen guys was a business that would heat treat our connecting rods and crankshafts. I had a crank guy that had more than forty years experience just grinding cranks. The shot peen company moved, the crank guy retired and the heat treat shop became extremely difficult to deal with.

Lack of convenient services makes the imported race parts more appealing.

That's pretty much what I'm getting at. With cost to make an old part usable, and finding a shop you trust to do proper work that actually cares about what they are doing, and on top of that finding the old rods you want to start with, it becomes a question of time and money spent vs buying something new, stronger, lighter, for not much more money. Granted I do spend a little money on the new stuff to fit pins properly and such but I much rather prefer a cap screw rod bushed with floating pins vs the stock stuff. Cost wise it's a wash to me.

[Dragncar]

Originally Posted by GTO-relic

Fireball Roberts set the pole for the 1963 Daytona 500 at a speed of 160.943 mph. This marked his third consecutive pole position at Daytona with a Pontiac.
The average speed for the 1963 Daytona 500 was 151.556 mph.
Pontiac 421 equipped cars finished 7th and 8th, ahead of Smokey Yunick's 9th place 427 Mystery Motor equipped car, who had defected from Pontiac to Chevy that year.
500 mile NASCAR race with average speed of 151mph, is a 3-1/2 hour race.
Using factory forged GM SD421 rods.
That requires sustained 6300rpm engine speeds for 3.5 hours.

Vintage forged, heat treated, USA-made connecting rods are not weak.

The SD455 rod is even stronger.

There is a big difference between rubber rods and early SD rods. The Sd rods had a noticeable ring to them when tapped together. Rubber rods did not because the steel was not as good. Even with better steel the beams are spindly.
SD 455 rods are "OK" but if Jim Butler himself tells me that those rods can break just looking at them sideways (he did) that tells you a lot.
No sense in living in the past. Hard to even find rubber rods anymore.
Its a fact that generic H beams are stronger (when checked out, just good cores) than any OEM Pontiac rod.

[PAUL K]

Originally Posted by Dragncar

SD 455 rods are "OK" but if Jim Butler himself tells me that those rods can break just looking at them sideways (he did) that tells you a lot.

Yes, it does. It tells you Jim has an unlimited supply of Eagle rods to sell.

[unruhjonny]

This is an interesting discussion.

Incase I missed it, does anyone have numbers on the "69-78" cast rods to compare against the other castings being discussed?

I believe this was the first mention of them in this thread:

Originally Posted by tom s

For a street only engine up too 4in stroke I would run a set of 69-70 cast rods before any of the 58-62 forged rods.JMHO,Tom

I had understood that the cast rods were good, but this prompted me to look at my McCarthy and other Pontiac books I had here, and I couldn't find a single mention of how the 69-78 rod held up against the others.

[tom s]

My experience with cast rods.Some years ago I was in AZ driving my then 63 Tempest convert on the freeway and all of a sudden the engine shook and stopped.Got the car back home,pulled the heads off and found one dropped a valve.The head of the valves went Xways through the head of the piston.Pulled it apart and found with all the damage the rod was still attached to the piston and the crank.With further inspection I found the rod had twisted a touch BUT held together that caused me when building a street 421 for my 62 GP to trust a set of rebuilt cast rods that came with the engine when I bought it in pieces.This engine has been in the 62 for some time with many diff intakes.It has the repo Bathtub mule from when we made them.The engine sees off idle to max of 3000 and never misses a beat.I have posted pics of the rod-piston assm a couple times on this site and if anyone wants a look,PM me with a cell number and you will have one.FWIW,Tom

[unruhjonny]

Thanks for replying Tom;
I seem to recall being in other discussions where I was scoffed at for proposing to "cheap out" by not buying aftermarket rods.

Seeing as my car is still a ways off from completion, I am trying to contain 'project creep' by setting a goal in my own mind's eye;
That goal has been to qualify for PSMCD - and I believe that an aftermarket rod is immediate disqualification.

Now, am I willing to disqualify myself from PSMCD for insurance against an expensive engine rebuild(?) - probably.

I will admit that although my engine (744 cammed 70-YZ) did see north of 5,800rpm on several occasion's - it sure didn't live up there... and prior to the scoffing I received here, I had no one give me cause to think that a reconditioned rod was a liability.

... ok I'll end my derail right there.

[Jay S]

The 1140 alloy the old rubber rods used gets what little strength that alloy has from sulfur and Manganese. The SD rods that use 4140 get their strength from Chromium, Molybdenum, and Manganese. 4140 is easier to heat treat, much stronger after heat treating, and more expensive to make. The 1140 alloy was likely never going to work well on any kind of large scale for Pontiac to heat treat them like the racing guys did. If Pontiac would have made the beams heavier they may have held up better. They are still fine for a stock engine if you have a set.


The 455 engine I did years ago that thru 3 of the early rods didn’t even window the block. The rods hammered on the block and broke into little pieces and went into the oil pan. We even reused the crankshaft they were on 2 week later. That says how strong that 1140 alloy is. A 4140 would have windowed the block after the first rod left the crank. From the factory, the durability of any of the SD rods is not very comparable to an early rod.

[tom s]

To put inprospective IF I would have had to buy rods it would have been a set of SCAT forged rods.Tom

[Dragncar]

Originally Posted by PAUL K

Yes, it does. It tells you Jim has an unlimited supply of Eagle rods to sell.

Maybe, but a good set of aftermarket rods is cheap insurance IMO. I sold my 455 SD rods to a guy who ruined one of his. The engine was only a high 10 second 428 with RAIV heads. Pretty mild.
A big Chevy builder did the machine work on my first 455. He never seen a set of SD 455 rods. He did not like the big end or the small end.

[Formulajones]

Originally Posted by unruhjonny

Thanks for replying Tom;
I seem to recall being in other discussions where I was scoffed at for proposing to "cheap out" by not buying aftermarket rods.

Seeing as my car is still a ways off from completion, I am trying to contain 'project creep' by setting a goal in my own mind's eye;
That goal has been to qualify for PSMCD - and I believe that an aftermarket rod is immediate disqualification.

Now, am I willing to disqualify myself from PSMCD for insurance against an expensive engine rebuild(?) - probably.

I will admit that although my engine (744 cammed 70-YZ) did see north of 5,800rpm on several occasion's - it sure didn't live up there... and prior to the scoffing I received here, I had no one give me cause to think that a reconditioned rod was a liability.

... ok I'll end my derail right there.

No an aftermarket rod does not disqualify you from the pure stock drags. In fact they encourage it. After 50-60 years you can't expect all those cars to be out there running factory rods. A good aftermarket rod is cheap safe insurance and many won't even take the chance with reconditioned stock rods and possibly tearing up their ride and/or oiling down the track

[Jay S]

Maybe Dennis will comment on what light weight internals are forbidden in the rules for PSMCD. H beam rods are considerably lighter than a I beam rod, while they might be a little beyond the scope of the rules for pure stock, most H beams rods are not light enough I would call them light weight. They would be on the edge of what becomes light weight. A stock cast rod is right under 900 grams and a H beam is closer to 680 grams. The old early rubber rods were in between those numbers. Aftermarket RPM and Eagle 5140 alloy I beam rods are considered a stock type service replacement rod. For most of the pure stock classes I know of you can also use lighter weight pistons with 1/16” rings. But lightened cranks, strokers, different length rods, aluminum rods, and pistons with narrower that 1/16” ring would all be outlawed in pure stock.

[Formulajones]

I've talked to Dennis about this years ago, where I got that info from. He welcomes aftermarket rods purely for the safety reasons.

As far as saving a few hundred grams with rods I seriously doubt it's providing any measurable performance difference. I'm sure they've discussed that and why it became a legal upgrade.

Pistons on the other hand, there is HP to be found there so that's more of a controversial subject.

[unruhjonny]

hmm, the wording appears to have changed;
As I recall a couple years back aftermarket rids were banned because the assumption was that they would be lighter - or something to that effect.

I am pretty sure I have an older set of rules saved on my computer.

[SD455DJ]

At the PSMCDR we do allow aftermarket forged steel rods. We can’t police or control what’s inside and hidden in the blocks, but we know most engines have Eagle, Scat, and we’re sure Molnar rods as well. Pistons go the same route, most use modern forgings that are lighter with the 1/16” ring packs. We allow what NHRA Stock class rules allow for the bottom end for the most part. As Formulajones said, we encourage stronger rotating assemblies for safety and longevity. Yes, it is a lighter rotating assembly and allows 2 to 3 tenths quicker et’s, but we don’t want any catastrophic destruction of any racer’s engines due to old connecting rod or cast piston failure in the name of “factory original parts.”

We are more concerned with the proper block (displacement), heads, cam, valve train, intakes, carbs, transmissions, rear ends, and, to a lesser extent, distributors being factory stock. We, personally, use forged aftermarket rods and pistons in the pure stock builds we do. We’ve had 2 Pontiac engines with cast rods fail on the dyno (fortunately our own engines and caught before breaking), even after careful resizing with ARP fasteners! That convinced us that we’re always going to use forged rods in every build we do…no if’s, and’s, or but’s. It's no more expensive to do so and well worth the peace of mind! We have had no failures/issues with Eagle or Scat H-beam & I-beam rods since the switch (20+ years).

We allow mini-domes on pistons in order to preserve original blocks from being decked to their limits as long as compression is no greater than 1.5 points above advertised. You might lose a little hp from the minor obstruction of the flame front, but it’s minimal. We’ve used Icon, DSS, Diamond, and Ross forged pistons with full floating pins.

We’re leery using 50-60 year old connecting rods and cast pistons anymore. We recognize we need to adapt by allowing better components for the race participants, or the race will end if we’re too idealistic.

Anyone that wants to run cast rods and pistons (or TRW/Sealed Power forgings), that is fine with us. I do see we need to update the rules to allow forged steel rods (still not allowing aluminum rods). Also, as ‘stock’ replacement cams become harder to find, we’ve implemented the 16” of vacuum at 1200 rpm minimum rule for most engines (RAII/RAIV, W30 stick, W31, DZ 302, L88, R/W Code 427 Ford, etc. that are ‘big’ cammed from the factory are exceptions and consider 12” an achievable minimum at 1200 rpm).

Granted, there are participants/racers that spend more money than I care to think about on their cars to nudge the 11.50 mark, but more power to them…as long as it’s legal by our rules…and the only thing you can win is bragging rights at our little race. The guys that have the most fun are in the slower cars (13.00 and higher). They don’t break parts and are reliable run after run.

Dennis