[mgarblik]

I am posting this thread as a general "heads up" for people building their own engines from catalog parts. I am not willing to reveal vendors because that's not the point. But this is what we have seen in the shop in the last 3 weeks in our engine building class. Student brought in a set of Chinese H-Beam rods. Very proud of the fact that they had ARP 2000 bolts. We measured them on the Sunnen AG-300 precision gauge. NONE of the 8 were usable as delivered. All 8 had .0008"-.0012" taper across the big end. They were ALL .0002" outside the large end of the tolerance for size. I had him send them back. Next set came in a week later. Exactly the same. We had to break them down, cut caps and rods and hone them. Came out very nice. I am almost certain they would have spun bearings if run hard. We have had two "Balanced Assemblies" Purchased and brought in. One Small Block Ford, One LS. Nice looking stuff. Balanced, YES. Balanced correctly....... well not really. The LS was out 14 grams on the front and 26 grams out on the rear. The Ford out 39 grams on the front and 55 grams on the rear. Bottom line here is: If your buying all this Chinese stuff, balanced assembly or not, please take all of it to a competent machine shop and pay a couple hundred bucks to have every piece checked out before assembly. Buying "Kits" and throwing it all together is just a crap shoot IMO. You may get lucky, but I haven't won the lottery in my lifetime. This is one of the reasons I am often recommending just rebuiding the stock rods with new hardware for mild builds. At least that doesn't drastically change the balance. Good luck out there.

[bhill86]

I appreciate this info and the time you took to post it. I’m a newbie when it comes to building engines and I’m trying to soak up as much as I can before I endeavor in building my first engine sometime in the near future.

[PAUL K]

Thanks for posting.

We've had many balanced assemblies come through our shop. Seven of the eight rods had never been taken out of their wrappers and it was obvious the pistons weren't all scaled.

[Formulajones]

I agree Mgarblik, I've been saying that for years. Even 30 years ago new rods weren't always perfect, long before all the talk of over seas parts. We always had the rods checked and in most cases the big ends had to be resized. Even on rods where the big ends were okay, I never had a rod where the small ends were ok. They have always needed to be honed a bit as the pins are too tight. Good higher end name brand parts too. I've been told by a couple machinists that they come that way on purpose as different machinists like to see different pin clearance for certain applications and certain HP levels and certain RPM goals. Some just throw them together and don't check at all. Some get away with it but I've always had to have them honed.

Case in point was the 455 I went through for John that had recently been rebuilt from another shop. When Paul took the pistons off the Eagle H-beam rods, they showed signs of the pins being too tight and would have eventually been an issue. Those got honed and fixed before it became one. Obviously it had been put together previously without checking.

I do the same thing with brand new cylinder heads, rotating assemblies etc.... They get sent to the machine shop brand new right out of the box to make sure guide clearance is right, springs are right, the valve job seals correctly, the balance job on the rotating assembly is correct etc... If you have a good machinist, he'll find things that need attention.

[JLMounce]

When we are talking about "kits" are we talking about catalog stuff like buying an eagle kit through summit? Does this also pertain to stuff that is supposed to have been gone through and measured/balanced, like what you would purchase through Butler, KRE etc?

[PAUL K]

Originally Posted by JLMounce

When we are talking about "kits" are we talking about catalog stuff like buying an eagle kit through summit? Does this also pertain to stuff that is supposed to have been gone through and measured/balanced, like what you would purchase through Butler, KRE etc?

At one point it was almost all the sellers of "balanced" rotating assemblies. Now, some have got better and atleast open all of the bags the rods come packaged in.... I'm not convinced the rods are actually weighed.

[mgarblik]

Originally Posted by PAUL K

Thanks for posting.

We've had many balanced assemblies come through our shop. Seven of the eight rods had never been taken out of their wrappers and it was obvious the pistons weren't all scaled.

Treading lightly here. We have NO Pontiac engines in class this time. However, the vendors I am talking about DO sell Pontiac Cranks and rods. I don't want to throw any vendor under the bus, we need them. However, nothing from Butler or KRE are being discussed here at this time. But that's not the point. I am personal friends with the Rodney and David Butler. But when I buy stuff from them, I check every piece anyway. I have NEVER had a out of spec. part from Molnar. Doesn't matter, I check every rod anyway. Piece of mind. To Paul's point, I think these mass marketed kits from Eagle, Scat, Summit and others are "Batch balanced". Meaning they weigh a sample of pistons and a sample of rods, come up with a bob weight, and then balance a couple hundred crankshafts or more to that same bob weight. No proof of my guess here, but for the low price they are selling this stuff for, I can't imagine each rotating assembly being weighed and balanced individually. Too labor intensive.
IMO, a "balanced assembly" that is off 14-16 grams on each end would not be noticed in a mild street build run a few thousand miles a year. It wouldn't be right, but a catastrophic failure is unlikely. The little Ford off nearly 100 grams on an externally balanced crankshaft would have some vibration that could be felt and a shortened engine life.

[Elarson]

Adding to that, I've long felt that the engineering and quality control of unmolested factory parts is superior to a lot of aftermarket stuff. I'd only replace factory parts if a person is sure they're not suitable for the power levels anticipated. Newer is not always better.

Eric

[PAUL K]

I guess maybe it would depend on one's definition of "balanced". But also when talking about rods it could come down to one's acceptance of useable. We've checked used rods that were farther out of spec than the OP's rods that were rejected. The "out of spec" rods were used as is in an engine producing more than 2k HP and went on to win its class.

What did the rod manufacture say in regards to the the rods being out of spec?

If I was a betting man, my bet would be they were repackaged and sent out to the next guy.

[mgarblik]

Originally Posted by PAUL K

I guess maybe it would depend on one's definition of "balanced". But also when talking about rods it could come down to one's acceptance of useable. We've checked used rods that were farther out of spec than the OP's rods that were rejected. The "out of spec" rods were used as is in an engine producing more than 2k HP and went on to win its class.

What did the rod manufacture say in regards to the the rods being out of spec?

If I was a betting man, my bet would be they were repackaged and sent out to the next guy.

I agree with your post. I have seen rods taken out of used good running engines that had more taper, out of round and with larger housing bores than these "NEW" rods. I did talk to the vendor. They were very nice and courteous. They agreed to send out another set postage free or refund the entire purchase. I also got the "vibe" that "we have sold thousands of these connecting rods without issue". Again, can't argue with that, but they are not right and not even within the pretty generous factory tolerances. Can't guarantee failure or success which isn't a good place to be when building an expensive engine. Pontiac has a spec. and a tolerance range. A fresh engine or new parts should at least be in that range. My student, who had never used a connecting rod hone, had all 8 of those defective rods +- .0001" for taper and size when finished. It did take him 2 1/2 hours to rebuild the big ends.

[PAUL K]

You have an important job. One has to learn the correct way to do something.

[Formulajones]

Originally Posted by JLMounce

When we are talking about "kits" are we talking about catalog stuff like buying an eagle kit through summit? Does this also pertain to stuff that is supposed to have been gone through and measured/balanced, like what you would purchase through Butler, KRE etc?

It pertains to all of it as far as I'm concerned. Some get by just fine. I prefer to have things checked no matter what the HP goal is, considering how much it costs to build an engine I can't afford not to.

[JLMounce]

Originally Posted by Formulajones

It pertains to all of it as far as I'm concerned. Some get by just fine. I prefer to have things checked no matter what the HP goal is, considering how much it costs to build an engine I can't afford not to.

Definitely understandable, but also just one more thing that starts making a modern LS/LT more attractive.

It's probably better at this point to have everything sourced through your machine shop of choice...and hopefully they aren't cutting corners.

[Formulajones]

Originally Posted by JLMounce

Definitely understandable, but also just one more thing that starts making a modern LS/LT more attractive.

It's probably better at this point to have everything sourced through your machine shop of choice...and hopefully they aren't cutting corners.

Yeah so long as low mile LS engines are available it's a viable option. Once age and mileage sets in we are back in the same boat.

What you said is how I am doing my current engine and how I've done them in the past. I gave Paul the block and crank, everything else is bought new and I wanted Paul to pick and choose what would be best ( ie: rods, pistons, rings, bearings, valvetrain parts etc..) Tell me how much money he needs and I pay it.

I look at it this way. I'm getting a custom engine with parts that I know someone as experienced as Paul is happy with. He's been around long enough to know better than me what is good out there and what is not so good. In the end I feel I get a better product, Paul is happy he's working with parts he knows to be a good foundation for what our goals are. It's not a cheap way to do it, but I'll know what I have when it's done and I trust Paul to do a top notch job on the machine work, it'll make good HP and it'll be reliable. In my opinion it's better than a crate engine.

The key here though is having a machinist you can trust that you know pays attention to the details. Not one that just pushes stuff out the door because it's "close enough" They are few and far between.

[Dragncar]

Every single set of offshore rods I have ever bought needed the big end honed. Except Molnar, they were dead nuts on.
Never bought a balanced assembly. Bought the parts I wanted and had them balanced. Who cares about the 100$ you might save.

[pgp66]

Without naming the seller what brand are those rods? Just so people that have bought them know to get them checked is all. Thanks.

[mgarblik]

Originally Posted by pgp66

Without naming the seller what brand are those rods? Just so people that have bought them know to get them checked is all. Thanks.

They have no brand name on them. They are nice looking H beam rods with a large center to center distance inked on them. Obviously Chinese. Sold on the internet and by various vendors. They do have what appear to be genuine ARP 2000 bolts in them. Or very good knockoffs. Sometimes we call these "White Box Parts" .

[sdbob]

Thank you for info. I would/am wondering if machine work is marginal what about metallurgy?

[mgarblik]

I don't know the answer to that question. It seems the quality of the machining is the biggest issue. The internet ads say all kinds of crazy things about power level capability. I wouldn't believe one word of that crap. Personally, If I was building a moderate to high moderate HP Pontiac engine, I would use Molnar connecting rods. A real person stands behind them. The machining is dead on. Reasonably priced.

[gtospieg]

I'm glad to hear good things about Molnar. After speaking to them at length I felt like I was getting a good product...4" stroker crank and rods and pistons and rings...balanced. I may still have my machinist check it all out.