Of course they're not assembled by robots. I figured that went without saying.

The parts are all made on automated machinery so things like boring, honing, rod sizing are not hand processes. Then, parts are "batched". They group things like pistons and rods into similarly-sized groups for assembly. They aren't machining-to-fit or precision balancing anything.

Also, you need to define "rebuilt" That usually means installing all new parts into a used block. If you're grinding a crank and resizing the rods on a beat-to-death motor, your odds of success are certainly lessened.

Chris brought up a good point about balancing. I have built many, many pairs of engines with the exact same parts. I may have only had one or two pairs that had exactly the same bobweight. GM does not weigh each rotating assembly and balance each individually. They use an average bobweight. I think their acceptable range is like 20-25 grams out of balance. I'm sorry but that is not good enough for me.
Now, this may not cause you a problem in a 450-500 hp, 5000-5200 rpm engine, but I am not willing to take that chance. It's not financially feasible for them to balance each and every one by hand and they have a certain percent of failures figured in. Now I'm not bashing GM, they do a great job at what they do. They just build a LOT of engines and can only give each so much time.
So, I am a little partial to a custom built engine.:D
Eddie

Ray, I sorta agree, and not.

There is no question that quality comes with the details.

But I think the 'who builds it' is paramount: its not the company who builds it, it the actual person.

Specifically: If Bob or Norm Teague personally built a motor for me, no problem. If some employee of theirs built the motor, I would feel far more confident if I had done it myself. FAR MORE. And I really don't know what I am doing.

I work on spacecraft. If anything is wrong, we lose the mission. There are literally millions of analysis done, decisions made, tests done, and anywhere in there can be the thing that kills the bird, or rover. Its not the logo, its the weakest link. I've got people with unbelievable experience and academic credentials that I've had to can, or I've forced out, because they just can't sustain the level of perfection under pressure required. Its those individuals, not the logo on the building, that screwed up, or that enabled the success.

With a big giant faceless company like GM, you really are just playing the odds. Most of the time, maybe the vast majority of the time, you'll win. If they were not pretty darn good, they would have gone broke long ago: a billion pissed off customers will kill the biggest company. Or you'd think so, anyway, but Microsoft is still with us :rolleyes:

But the thing is, engines really are not complicated. The most worn piece of junk will run. But paying attention to the details, and building on experience and wisdom, will probably result in a better engine for you.

And experience is not enhanced by doing the same thing a million times over. Its enhanced by experimentation -- by trying things a little different, and paying attention and tracking what works and what does not.

Bob Teague and Paul Pfaff are two who do this: they build and run and fix a lot of different engines for a lot of decades -- engines they built, and engines others built. They learn!

Does a guy on an assembly line who simply builds engines all day, and never fix ones screwed up by someone else, does he ever get any wisdom?

Does a production line run to meet quarterly reports for Wall Street pay attention to, say, how putting the alternator under the power steering pump causes the alternator to fry when the power steering pump leaks?

Experienced custom builders are the way to go, in my opinion.

Just as a data point, Yanmar's 3.3L 4 cylinder diesels built in Japan are nearly 100% automated. I did not see the factory first hand, but two engineers I used to work with did. They said it was amazing to see the engines being put together by robots. That also includes and sealant, gaskets, etc. Torques were all by DC torque wrenchs - very precise and accurate.

I have no direct knowlege but would assume many automotive manufacturers, especially those in Japan, are nearly 100% automated.

If you visit gmperformance.com they show their production line where the engines are assembled. One guy, one engine.

It has probably already been said but in the lower hp ranges, I don't know if a builder can compete $ wise with some of the crate packages, if he is using new parts. I think I'll get agreement, majority of GM problems are valvetrain oriented. In higher hp configs I think this is where the builder can really add proven value. Personally I would rather have a custom built anything vs factory but I am willing to pay the difference for the value received....unlike John Doe.

http://boatingtodaytv.com/feature/lastweek.asp Hope this helps.:drink:

Last I knew Merc charges big money for one of their engines. You can have the same amount of HP from custom engine building shop for much less than what Merc charges. (How much does Merc charge for one of their 1075's? I understand Merc builds their own higher echlon hi-perf engines and Merc may have the lower echlon engines (short and long blocks) pre-assembled from GM. I'd rather have my engines built by someone who knows what the heck they're doing and not give all the deceptive smooth talk as they con your hard earned green backs out of your wallet.

Ha...and finding a shop that knows what the heck they're doing when it comes to hi-perf offshore engines and how they deal with you as a business can be another whole challenge in itself! Hope it goes well for you.

If you have something to add that might educate us, please add it. If not, why waste all of our time with your barbs?

Well said. Probably a good word for it is "Blueprinting". I have been told that .001" can make a difference in the survival or disaster of an engine. Taking all the slop out of a mass produced factory engine and have it built/fitted within a certain set of specs by a competent engine builder is what I would prefer to do.