J & M Machine Co Inc - Southborough, Massachusetts

J.R B

I've been a loyal customer of John at J&M Machine for years, even driving two hours to deliver customer parts to him, especially because their service was exceptional. However, my recent experience was disappointing. I entrusted them with rebuilding a 2020 Cummins engine, equipped with aftermarket internals. I provided high-end parts and emphasized to John the engine's high horsepower and compound turbos. Yet, after they struggled to find certain parts, I found myself driving a total of eight hours to provide items they could have located with some research.

Moreover, after reinstalling the engine in the truck, with less than an hour run time, we heard a knocking sound, which we initially mistook for "fuel knock," unaware that it could be related to the machine work. After pulling and cutting open the oil filter to find a enormous amount of metal from just 45 min of run time and hours of diagnostic work revealed that JM had not taken the time to properly measure any specifications for the engine's assembly. John spoke with a representative from the engine parts manufacturer, who confirmed that they had no record of the settings used, resulting in the new pistons scoring the cylinder walls and thus ruining everything that had been done, including thousands of dollar's worth of parts.

After noting this, John and I discussed the matter. John informed me that the rings were not "file fit," hence no clearance adjustments were made. How could an engine builder neglect to ensure this is correct? John, with your experience of building hundreds of engines, especially of this caliber and horsepower rating, it's inconceivable that you wouldn't check this. And then to tell me there's no warranty, holding us responsible for the parts that were damaged in less than an hour of running time? Then to proceed to say "welllll you didn't tell me" Why should a customer be responsible for relaying that type of stuff to you? You are providing the service... not the customer... Go ahead and say we are at fault for not providing information to you, maybe if you were organized and wrote things down perhaps the outcome would be different. I specified the power rating and the fact it had a aftermarket turbo set up, plenty of times.

Thousands of dollars spent, hundreds of customers referred, and yet you can't stand behind your own mistakes. Your "no warranty" policy should not cover poor craftsmanship and lack of responsibility. Perhaps it's a deficiency in understanding and skill regarding modern engines?

All I know is that you've lost a very loyal customer. Every one of these reviews pertains to a 1930 engine you rebuilt that can tolerate being three-thousandths off specification. To prevent this, all you needed to do was make it right, not let me leave your shop upset, with thousands of dollars in parts tossed into a bucket.

Edit - Your response is irrelevant and speaks it self to your professionalism; if you took the time to make sure the specifications were correct by reading the email below I'm sure we wouldn't be in this scenario. Bonus - we had to replace the block it self as all cylinder walls were scored, and 5/6 pistons were completely destroyed. OH - lets not forget about the rounded crank main cap bolt, perhaps wrong size socket?

- J.R

Justin G

I would highly recommend J&M Machine co to anyone. I am currently rebuilding the engine on my Ford 2N tractor. I brought the components to John after issues with a prior shop. I am extremely happy with how everything has come out, and feel like i have been setup for success on the build. John’s recommendations and guidance has been instrumental. The block needed a lot of work, and my crank had been ruined by the previous shop - but with Johns help things are back on track. Got a new crank, block was rebored for over sized sleeves and new valve seats were installed. Everything came out excellent, and its great knowing taking the time to do things right now will pay dividends later. Thanks John!

Tyler Wasson

John is an excellent machinist and great guy too. Knowledgable and helpful in every sense. They do great work, are consistent and fair.

MLRACINGENGINEERING

I was looking for a reputable engine rebuilder/machine shop after I tore my drag racing engine down at the end of the racing season and discovered that the thrust surface was worn on the crankshaft resulting in excessive crankshaft end play. I had some work done at some other shops before and had some bad experiences and started looking for another shop and found J&M. So I called J&M and John answered and I asked about repair but after taking a trip to J&M and speaking with John in person we decided best route was to replace the crankshaft. Discussed the vendors and what was available and with the current supply chain issues we knew it was going to be a challenge to find something in stock. However I did find a 4340 stroker SB Chevy crank at Ohio Crankshaft after John had mentioned that I should try giving them a shot. Well they had it in stock and shipped immediately. Once I met John and discussed all the technical aspects I knew I was at the right place to perform this work. I wanted to find a shop that has the knowledge and expertise when performing this critical work. Attention to detail is the most important aspects when machining and engine building and John has those extremely important skills. John and I had a lot of technical conversations and I am very happy that I know him. I am a perfectionist myself and want things correct. I brought all my components, rods, pistons, pins etc. to John to have him balance the entire assembly including flywheel and pressure plate. Sent me progress photos during the process in an e-mail and turned it around in a week complete with print out of all technical info, bobweights etc. And he has an electronic record also. When you are spending money to build any engine you want to spend the money once! Parts are expensive and too many times other shops perform work that is sub-standard or just plain poor. Not to mention the work that needs to be done over and in a lot of cases you find out that the money you spent the first time was a waste and damaged components that were good before and are now damaged and cannot be repaired and you have to buy new. Open your wallet because that $$$$$$$$ you spent on the deal you got wasn't a deal after all! John is honest and tells you what you got or didn't get. He is a straight forward no nonsense man. His work is the best I have seen to date and I have worked and done business with many machine shops over the years. His equipment is top notch and state of the art, well taken care of and his work ethic and technical knowledge is impeccable. Don't go anywhere else when you need this type of work done period! You will not find anyone else in this business that does what John can do! There is no close enough or that's good with John! It's either right or not and after meeting him and doing business with J&M I cannot emphasis enough, don't spend your money anywhere else, you will not find a better shop or person like John. I have great respect for John & J&M Machine you won't find better! BY the way, they need more Stars 5 isn't enough!

John, I thank you for showing me everything on my first visit and the opportunity to get to know you! I posted a few of the pic's you sent to me during the work.

Steven

I have nothing but good things to say about my experience working with J&M for the first time. Clearly extremely knowledgeable machinists who stand by their work. I will absolutely continue to use them for all my machining needs!

Braedyn Luiz

Nothing but good things to say. Great guy, great work and very fair pricing. I will always make the extra drive to go to J&M

Jeremiah deOliveira

I recently had my L28 rebuilt by J & M Machine for my 1978 Datsun 280z, and I couldn’t be happier with the results! They were incredibly friendly, patient, and professional throughout the entire process. They demonstrated a deep knowledge and expertise in their work, ensuring that everything was done to the highest standard. I highly recommend J & M Machine to anyone looking for top-notch service for their engine rebuilds. A truly exceptional experience!

William Casarsa

John built me a short block for a higher hp turbo Miata almost 2 years ago. Right off the bat he took the time to discuss my goals and was honest about what would be needed. This was the first motor build I have been a part of and John took the time to answer all of the questions that I had. He was very timely with his work and sent me pictures and updates as he went which were very nice to have. I ended up being the reason for delay as I ordered numerous incorrect parts including “brand new” head that John inspected and informed me was in fact not new at all. His communication was top notch and to this day I have not worked with anyone as up front and transparent as J&M. He was very patient with me and I was so impressed with his investment in the project-it felt as if he cared as much as I did. The motor has been running strong for the past year and I cannot thank and recommend this shop enough. Hope you’re doing well!