J & M Machine Co Inc in
Southborough Township (MA)

John is fantastic to work with and helped me a lot on my Ford 393w stroker motor. This was my first build from scratch so I had a million questions; John was patient and took the time to really help me understand the right way to do things, answered all my questions, and helped guide me to the finish line. These guys do meticulous work at a reasonable price; I'd give more stars if I could.

John and Michael were great to work with. They were very knowledgeable and honest when it came to building my Ford Model A engine. From start to finish it was a great process with pictures along the way. They also installed Hub bolts in my new cast iron drums and machined them. I traveled almost 2 hours each way to use their services. It was well worth it. I was amazed when I visited the shop and they gave me a tour around to show me the different jobs they were working on. Their business is top notch and they will give you the best advice when it comes to getting any maching done. Thank you John and Michael for the work you've done for me and now I am smiling and enjoying my Ford Model A.

Got my head resurfaced here, John was great, great results, and good prices. Can't complain! Will definitely be back in the future

Excellent service! John and Mike are very knowledgeable and helpful. I use them every time I need a machine shop.

Spoke to John today. While I will not be buying anything from J&M his sage advice and insight was super helpful as I explore the remanufactured engine market. My first time. I feel better having talked with him. Wish I could have done business with them. Thanks John!

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

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!

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!

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

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!

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!

John really is an expert in his field. He not only takes the time to get the job done right, but takes time to understand your engine building goals and make sure you understand the important details. Reasonable prices and turn around time. If you want it done right, and to learn a few things along the way, John is your man.

Did a fantastic Job replacing the valves in the heads of my Honda accord v6 Manual trans. Engine runs beautifully now. Dropped the heads off in the morning and he had them done for me by the end of the day. Very fast service Super nice guy and has a ton of knowledge. Plus the shop is filled with all sorts of cool stuff. Can’t wait to do more business here. Tom @ Universal Auto Repair and Sales

I had great results and experience getting a cylinder head machined here! Reasonable price and great help/advice. Very professional

I've been going to J & M Machine for a couple years now and they've never disappointed me. A couple mouths ago I had D25 subaru heads all redone. Head studs clearenced for ARP 14mm bolts. All new GSC valves, retainers, springs and guides all replaced for GSC S2 cams. The amount of time these took was less than expected. I highly recommend these guys if you want a quality job done right for your project.

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.

I’ve only ever had 2 experiences with automotive machinists: the first shop let my block sit for 6 months before they even cleaned it. I gave up on that place and found J and M, more than an hour further from me but I’m glad I did. They had my ej25 decked, bored, honed and rotating assembly balanced in a little over a week with progress updates throughout. It was by comparison a small job for them but they didn’t put it on the back burner. A+

I have been very happy with J and M Machine. They are rebuilding my Boss 351 Mustang Motor. John disassembled my motor quickly and gave a detailed written estimate that i felt was more than fair. I am impressed with the professionalism and communication that I have had with John. John has communicated frequently with me as well as sending pictures of my parts being balanced throughout the build. John has answered all of the many questions that i have had. He has been very patient as i have run into parts sourcing issues during covid. I could not ask for a better experience.

I recently had the pleasure of working with J &M Machine, I had 2 large challenges, I had a 1995 Pontiac LT1 which had thrown a rod, My original plan was to buy a short block and swap it. But as everyone knows right now supply for parts has really long lead times and I was quoted 6+ months for the short block if any came available. They were able to repair my damaged Block, balance the engine, rebuild the heads and provide me with a wealth of knowledge on the LT1 engine. This engine runs incredible, the project was done in a few short weeks as expected and on budget to the original estimate. On top of that I was rebuilding an older John Deere Bull Dozer, The blocks are unavailable and mine had a huge hole in the side of it, Their expertise in stitch welding was flawless, as well as other things I never thought of like demagnetizing connecting rods, removing stuck cylinder sleeves and rebuilding a very old Head again unavailable and now as good as new. I recommend J & M to anyone I can, their work is impeccable.

It's not like me to write reviews however after being a long time customer of J&M Machine , I need too. I just recently broke in another one of my engines from J&M , a perfectly machined and balanced 355 SBC Chevy with instant throttle wind up and pulling power. I've had these guys do several engines for me now over the years from SB/BB Chevys to SB/BB Olds , nothing but reliable unsurpassed quality. I wish to thank John and Mike for everything they do for me with current builds and future ones , I strongly recommend their services to anyone......... Thanks again to J&M Jim Cox

I found this shop after trying another having an unsatisfactory experience with another big name race shop in the state. The gentlemen that run J&M Machine Co are professional, charge fair prices, and do the best quality machine work I have ever paid for. I even dropped off heads for machining the gasket surface at one point and they informed me that I should perform a valve job. I didn't have the money to do it at the time, so I grabbed the heads and brought them home. Not taking their advice, I installed the heads and ended up chasing my tail for over a year with a misfire. I just found that valves were hanging up, causing the issue. Looks like I should take their advice and fix them right. If I need machine work, I will use J&M every time. Out of 4 machine shops I have worked with, J&M are head and shoulders above the rest.

John was a pleasure to work with as he is dependable and honest. I never write reviews but was compelled to write one here because of how well these guys did for my small job - boring out a Honda 400ex sleeve to 88mm from stock bore - including additional prep work like sand blasting the years of dirt off the exterior of the cylinder to increase heat exchange. They were good with post-sale advice and follow up and never made you feel unwanted, which is rare in 2020 - especially at a machine shop.

John at J & M was fantastic to deal with. I brought him my Duramax heads for machining and as soon as he looked at them he was able to tell where the head gasket had blown on BOTH sides. Upon closer inspection he realized they would need much more work than just machining. John was honest and told me it'd be more economical to buy a new set of heads rather than rebuild my current ones, and was completely understanding when I chose to do that rather than have him rebuild mine. If I do have to have any machining done in the future, or know of anyone that does, John at J & M would be the FIRST place I would recommend, A+ service

John is extremely knowledgeable in engine building. He has helped me build 2 high horsepower Miata 1.8 engines (bored over, forged internals, ground and polished crank, oversized valves, hd springs, full balance, etc). He is honest about his pricing and has a strong opinion for doing things the right way. He will also always tell you the most cost effective way of doing something even if it means he doesn't do the job for you. I will be using J&M for all my engine building machine work in the future.

I recently had my 1973 Triumph TR6 engine rebuilt by J&M and the results were fantastic. I was immediately impressed with John's knowledge of such an old engine. He knew of all the original engine manufacturing flaws and more importantly how to eliminate them from the new rebuild. John helped me decide on which improvements I should consider and also put me in contact with a great mechanic to help with the engine install. During the entire rebuild process John kept me updated with pictures and emails and if needed phone calls to discuss next steps. It was a great experience working with J&M. 7/29.2016 Paul T. Leominster, MA.

J&M Machine does fantastic work and backs it up with great customer service, attention to detail, and quality standards. When I first contacted John about rebuilding a 428 Pontiac motor for my 1969 Firebird, he immediately sent me dozens of photos of current Pontiac projects he was working on, and explained the entire process and all of my options very clearly. When we started working on it, he determined what could be used from the old motor, and wouldn't consider any shortcuts. The block was magnafluxed, bored and zero-decked. All of the tools and machines are top quality, and all of the parts that went into the engine were either original, and properly machined, or top-shelf replacements. As an example of the extreme attention to detail- we had originally decided on a rotating assembly from a well-known vendor, but when the parts arrived, the rods had been over-machined by 5-12 thousands each. John knew that this was incorrect, out of spec, and the motor would lose oil pressure. The vendor said to just throw them in anyway, but John refused, and then contacted engineers from several top engine parts manufacturers for their opinion (who all agreed with him). He then explained the situation and the mechanics behind it to me very clearly, and made a recommendation to return the parts. I agreed, and we then went with an original 455 crankshaft and new forged rods and pistons, and John cleaned up the crank and balanced the entire assembly flawlessly. His advice and expertise here absolutely contributed to making a better motor (which has fantastic oil pressure). Throughout the whole process John was always in communication with me, giving me updates on the progress and sending a ton of pictures. John assembled and painted the motor beautifully in the correct Pontiac blue, and gave me all of the documentation (the "Blueprint") for the motor. You can really see all of the effort that goes into each and every detail, and the final product clearly shows that. My motor runs perfectly, and is so tightly balanced that it revs up faster than any motor that big has a right to. The motor is exactly what I wanted, runs on pump gas, and makes great torque and power at any rpm. The range of expertise here is astounding as well, from old school straight-8s and V-12s, muscle car v8s, to late model imports, to giant diesel motors, hot rods, and more- and that's just what I saw them working on when I was there! I would definitely recommend J&M Machine shop for anyone looking for a machine shop that prioritizes attention to detail, communication, customer service and has top-notch equipment, a wide-range of experience and commitment to doing things the right way. I will be back to work with John on any other motor I build.

I had a 1926 Model T engine & transmission rebuilt by J & M Machine Company. They gave me an estimate of what it would cost to rebuild the engine & transmission better than new. The actual cost was very close to the estimate. They kept me informed as to the progress they were making and sent numerous photos of their work in process. The engine and transmission looked terrific when I received them back. I am now working to install the engine & transmission. The car will be of show quality when I am completed. Thank you guys for during an outstanding job of rebuilding and painting. Can't wait to get it running and in car shows.