CNC Machine work vs Old Style
Companies like Texas speed and other engine builders do offer limited warranties on their work depending on use. This isn't you giving a questionable fish to a chef and complaining you got sick. Your block is the only question mark in this build and they would know of any issues there during the cnc work. This is about as fresh a fish as it gets with them refreshing the block and using new in box parts. Personally, I'd still just have them finish the block and keep looking for another builder.
I am a vehicle mechanic for the Air Force. I have 12 years of tranmission replacement, head work, and doing lots of parts changing. I just have never done an engine build. I do have torque wrenches at home and thousands of dollars in tools at my house. How hard is it to assemble the short block. I worry about not having the right oil clearance and making sure the rings are filed right.
Really, instead of an electric motor, your hand is controlling the work piece position. You still read to the same numbers a computer does.
That said, we got to the moon with slide rules.
Personally I'd stick with CNC where possible if it's a common part/operation as the program will be on point. It'll either crash the tool (destroying your work piece) or come out perfect, with a few very rare exceptions between.
I'm no CNC ace, just an operator for a few stints (3 axis, 5 axis, and a brand spanking new Nakamura 6+ axis dual turret) plus done a decent amount of manual milling.
If you really want to worry about exactly precise tolerances, the temperature of the room can make a difference, let alone the machine and method you use..
I am a vehicle mechanic for the Air Force. I have 12 years of tranmission replacement, head work, and doing lots of parts changing. I just have never done an engine build. I do have torque wrenches at home and thousands of dollars in tools at my house. How hard is it to assemble the short block. I worry about not having the right oil clearance and making sure the rings are filed right.

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Really, instead of an electric motor, your hand is controlling the work piece position. You still read to the same numbers a computer does.
That said, we got to the moon with slide rules.
Personally I'd stick with CNC where possible if it's a common part/operation as the program will be on point. It'll either crash the tool (destroying your work piece) or come out perfect, with a few very rare exceptions between.
I'm no CNC ace, just an operator for a few stints (3 axis, 5 axis, and a brand spanking new Nakamura 6+ axis dual turret) plus done a decent amount of manual milling.
If you really want to worry about exactly precise tolerances, the temperature of the room can make a difference, let alone the machine and method you use..
OP - have you looked into the cost effectiveness of purchasing a short block from one of our sponsors perhaps? I'd personally feel better having a pro assemble a motor even if I could probably technically do it. And it seems like a lot of the reputable builders give some kind of warranty on common setups.
I own a CNC machine and have been a machinist for over 15 years, so Im still a newb, but in my experience the guy that has run that same machine for 30 years will spit out a better product. Will the CNC shop do good work? Yes. Is it worth $1200 more? No. What your paying for is the one time setup fee or the so called "warranty". I also work for a shop that builds race engines and there are so many ways around a warranty claim its stupid.
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Even a cheap newer CNC machine will hold hole roundness within .0005" or less. And that is circular interpolating the hole with an endmill. You are lucky the bearings run that true in 95% of the manual machines out there.
If the tools are set-up correctly, the program is correct, and the fixturing is good, you won't come close to matching the accuracy of a CNC.
Boring Heads and Indicators is what I used to hold .0002+/.0000- did it take a long time? hell yea
But going to the point, you probably could buy a short block from any of the sponsors here with a good warranty and be good for a decent.
Even a cheap newer CNC machine will hold hole roundness within .0005" or less. And that is circular interpolating the hole with an endmill. You are lucky the bearings run that true in 95% of the manual machines out there.
If the tools are set-up correctly, the program is correct, and the fixturing is good, you won't come close to matching the accuracy of a CNC.
Im not sure you quite understand how honing the cylinders and bearing bores works. An end mill and circle interpolation move is not used to create that plus or minus .0002" tolerance. Honing stones in a honing machine are used. Some will argue that the CNC version honing machine creates better cross hatching and that once a stone/program is setup every bore is identical and perfect. I have seen every hone off our manual machine come out perfect when operated by the master. The new kids, not so much.
Ive also made 5 billet blocks and from experience can tell you circle interpolating a 6" x 3.5" hole with an end mill will never achieve a .0005" tolerance on any CNC mill. Even if you split the cut up and do it 3" at a time. A boring head is used to get to within .003" and then the rest is honed out
I'd vote ERL if I let anyone else build my engine
SDPC has a sale on engines right now.
https://ls1tech.com/forums/sponsor-s...k-special.html
I am sure are other sponsors such as TSP can work with you as well.
If you have a good block (sounds like you do) and go with quality rotating assembly (sounds like you are) I think you're fine and maybe doing what lots of us tend to do - over think it.
Summit has a Blueprint forged 408 for $3,700. I see another one on ebay for $3,500. Both are plus freight. Unless a sponsor can reach out and offer you a nice deal it seems to me that you should take it to the old school guys. Warranties are nice but I don't see anything about warranties on short blocks. Could be wrong of course, but seems to me it would apply more to long blocks.
If you have a good block (sounds like you do) and go with quality rotating assembly (sounds like you are) I think you're fine and maybe doing what lots of us tend to do - over think it.
Summit has a Blueprint forged 408 for $3,700. I see another one on ebay for $3,500. Both are plus freight. Unless a sponsor can reach out and offer you a nice deal it seems to me that you should take it to the old school guys. Warranties are nice but I don't see anything about warranties on short blocks. Could be wrong of course, but seems to me it would apply more to long blocks.
I just Ordered an engine like 2 weeks ago from them. On top of that I ordered a bunch of other parts needed to put the motor together and was able to get some additional savings for buying so much stuff.
Another friend got one from TSP recently and it looks really nice they way they CNC everything.
With places like Summit, your going through a third party.
Buy going direct to a builder sometimes they can save you additional money.
Some times they also get special deals on parts that they can pass along.
Again it never hurts to reach out and ask nicely!
If you have a good block (sounds like you do) and go with quality rotating assembly (sounds like you are) I think you're fine and maybe doing what lots of us tend to do - over think it.
Again thanks for the replies, and comments. They for sure made me realize I was over thinking the process.
It sounds like you have a good machine shop.
You may want to pick up a copy of "How to Rebuild GM LS-Series Engines" by: Will Handzel
Ive also made 5 billet blocks and from experience can tell you circle interpolating a 6" x 3.5" hole with an end mill will never achieve a .0005" tolerance on any CNC mill. Even if you split the cut up and do it 3" at a time. A boring head is used to get to within .003" and then the rest is honed out
BTW...yes, I can interpolate a bore that depth and diameter with an endmill. It might take a few spring passes to relieve the tool pressure, but it is possible. Why you would do it is another discussion altogether.
To be clear, unless you are going to blueprint the block and machine most of the surfaces a second time, I am not sure why you would even need a CNC machine. I used a CNC to bore my cylinders, deck the block, bore the mains, and bore the lifter bores after I sleeved them, but I had the machine sitting there and thought it would be cool to mess with it. If I had to pay for that service, it would have been $5k
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