Stock rods in prebuilt engines?
 

I'm looking into buying a short block since the one I was going to rebuild was cracked. Still have a lot of other parts like timing cover, intake, etc, so I figured a short block would be a good way forward. I've found several companies that sell short blocks and complete engines, but they all say they use resized stock rods for their stock-style offerings. Should I be concerned about it? At least one company has been spoken well of here, so I would assume they know what they are doing. Still, I punched 'rods' into the search bar here and I didn't see any reason to use stock rods over an imported forging.
Use case is just a street cruiser, no more than 400 hp needed(for now). Would asking for a set of Eagle rods be insulting to someone who builds engines for a living?

Stock rods are fine for your usage as long as they were magneticlly checked for cracks and re-sized with new rod bolts.

With the 3.750” stroke of a 400 cid motor there safe to an easy 6000 rpm which is well higher then a cam for good cruise usage will make power .

As long as it’s a reputable Pontiac builder, and not some unknown from the FB, it should be ok for your application but I would definitely ask for the upgrade and a good builder will have no issue with that. What companies are you referring to?

Being they use factory rods it tells me the engine is being completed as cheap as possible. We still use factory rods occasionally but they are fully checked, prepped and use ARP bolts. I think a better sign for the quality of the build is check if the pistons are cast, if they are that's a sign of a bottom bid build. Personally I would walk away if it has modern cast pistons. There has not been a quality cast piston available for more than two decades. Of course there could be the rare exception if the builder came across an "old stock" set of pistons.

If the shop is offended by any question you ask ..... Leave and find a different shop!

Len Williams, I've seen them mentioned here before, and Pontiac Speed Shop. I don't know anybody in this business, I'm on the left-hand side of the Rocky Mountains

The 421 build will get stock cast or rubber rods; all depending on the big-end check.
Back-burner till the move dust settles.

Your flag out nuts if you use the rubber rods on a great 4 bolt block like a 421!

I would way more trust rebuilt late type cast rods then the early steel rods or even the steel 421 HO rods.

Now if you sent the steel rods out to be Cryo treated after you polished them then that would be a different story.

There’s a common sentiment on this and other forums that the rods should be replaced with new Chinese forged rods because of the labor to properly set up Pontiac rods but yet, I’ve never seen anyone here report on rod failure in the last few years that I’ve been on this board. Is it internet lore or because you’re there syndrome or whatever, not sure but my current stockish build is getting new rods per my request “just in case”

If you are going to want more power down the road, plan ahead and get better rods. At this point you should build the bottom end for your end goals. Stock rods are fine for certain applications and "can" provide years of dependable service. I ran them in modest engines but used a rev limiters for added insurance. Paying to rework the stock rod and getting good bolts will not be much cheaper than upgrading to better forged rods. That's the no brainer part and the reasoning forged rods are an SOP now.

Ask for forged rods, I’m sure he will have no issue with it.

len willkams generally uses srp pistons and eagle forged I beams in his builds. i think he will put in whatever you want though. he is local to me and ive had him machine a couple blocks and cranks for me...

Or is it because no one who builds a Pontiac with stock rods revs it high enough to do damage because they know better.

I’ve had or been in the car when two stock 455s spun rod bearings because they were taken too far. Was it the rod bolts or the cast rods or not enough oil pressure? IDK but I know I won’t rev a stock standard 455 past 5500 ever again.

The 24 odd Cast rods i have (8 had original bearings in darn-good shape too) are most likely gonna field the 8 candidates. Geez, the original 8 bearings are tempting me to reuse em.

The rubber rods look like a good set, yet not thrilled with the big-end design. not thrilled with belt-sanding & polishing em. The forged TRW pistons had the rubber rods; i pressed em off.

These TRW pins measure 1mil oversize from stock. That makes a big press-force difference. Likely need to hone the Cast rod holes

My last engine had the SD-455 rods (sold the car with engine), so i can live with factory Cast rods, unless i trip over a nice SD-455 set.

The cast vs Chinese forged rods debate will likely continue as long as most of that care about Pontiac V-8's are alive. From an engine machinist view, this is what I have experienced. A set of 50+ year old stock cast Pontiac connecting rods will work just fine and not fail if PROPERLY rebuilt with new ARP or SPS connecting rod bolts. I would only use stock rods that don't show any signs of overheating, (black/blue color) or a spun bearing. Also black or blue small ends that would indicate overheating when the pins were installed. A matched set from an old B body engine or a 2 BBL. engine are usually best because they generally haven't had the crap run out of them.
Now, as far as Eagle forged rods or other cheap aftermarket forged rods. They have different issues. No doubt in my mind at least, they are far better material and stronger than the factory Pontiac stuff. BUT, the machining is inconsistent, and unpredictable, period. They MUST be inspected and corrected before use. Buying a set of Eagle rods, taking them out of the box and installing them is NO better than taking a set of rods out of an old junk Pontiac and installing them without inspection/rebuilding them. The results are exactly the same, a failed engine. As I have stated many times, Eagle connecting rods are MUCH better than they were 15 years ago. Back then, 50% of them had to be rebuilt before use. Didn't matter what engine they were designed for. Now the failure rate is 7-10% after 15 years of improvement. I don't mean 7-10% of the engines fail, just 7-10% of them fall outside the factory tolerance for taper, out of round, pin bore specs., or width.
Bottom line is every connecting rod, no matter where it comes from needs to be checked for all it's dimensions no matter what the end use. A quality engine builder like Len Williams surely does this because his reputation depends on the connecting rods staying inside the engine where they belong. Good luck with your build.

I'm not a huge stock pontiac rod fan. Especially as this stuff just keeps getting older and harder to find.

I haven't used a stock rod in a Pontiac build in probably 25 years now. And when I did I had a set of 16 and ended up discarding 4 or 5 of them to get 8 good ones that were even deemed rebuildable. They were resized with ARP bolts and served the purpose well. But these days I ask myself........why use them now? The cost to go through them properly gets you half way there to a decent set of forged rods with a good cap screw bolt.

As far as Eagle rods go, Yes many years ago I had to have some of them resized right out of the box, they weren't "round" enough with the proper crush for the picky machinist I was using at the time. That also was probably at least 20 years ago.
Lately they have actually been pretty good. I recently bought a complete Eagle rotating assembly for another project and sent it to the shop for balancing. Had Mike check the crank and rods over while it was there. He liked what he saw and everything checked out nicely. Not necessary to resize a single rod and the bushed small ends were perfect, didn't need "touched up" as they often do. All clearances were spot on and it all balanced fairly easily.
That was also my experience with a cheaper set of Eagle "sportsman" rods I used in another build about 7-8 years ago with the exception of a light hone on the small end for proper bushing/pin clearance based off the rpm that engine was going to turn. The big ends were perfect.

My last set of the eagle 3D rods were perfect. Light hone on the rod end cost me $30, everything else was spot on. Looks like China has eliminated the QC gap that once existed.

A friend of mine who used a early set of Eagles spun two rod bearings on his 2nd mid 12 second pass.

FWIW, I have a newer set of Eagle H Beams in my engine that was built in 2024. The machinist needed to do some light honing for proper clearances for the pins, that was basically it on that set.

That same engine had a set of old TRW slugs hung on factory rods, with factory hardware that was installed without much care of side clearances and it lived for around 25 years before it tried to spin a rod bearing. Many trips to 5700rpm on a 4.21" stroke and they were fine.

From what Ive been told from more than one machinist is that today's rods that are bushed on the small end are purposely tight and meant to be honed to size. Everyone seems to have their own ideas of what that clearance should be based off a bunch of factors and experience. So it's something Ive always had checked regardless of where the rod comes from. Sometimes I've had them honed and once in a while it's not necessary

So the small ends I kind of check those off as a given, it's part of the process of building a proper engine. It's the big end I'm most concerned with and you would expect to be correct out of the box. It's when you have to spend money in that area that is discerning. The last few sets I bought the big ends were perfect.

The Eagle rods were so bad years ago, that I had to call them and buy a plastic bag of their guide bushings for the rod bolts. Because there were so many out of spec big ends many needed to be cut and resized before use. You might say why not just send them back? We tried that several times and the replacement set was often worse. So they sent me 100 bushings for like $100.00 and we were good for 4-5 years. Very hard to remove them and reuse them.