Bought their SP04 short block in April 2018. Machining was well done, measured everything before proceeding with building it up. The decks were cleaned and squared and all pistons were consistent to within .002 of each other (.014 - .016). Chose a .026 gasket for a good quench of .041. There was one guy who reviewed after he put together a 6.0l and bolted on his heads without checking PTV clearance or deck height. Bent valves and scarred pistons isnt ATKs fault. And the guy who chewed up 3 distributors in a Mopar engine- sounds like incompatible materials between cam gear and distributor gear. Keep feeding your mains metal chunks of your distributors and guess whatll happen? Right.Folks, building engines from a short block or doing proper prep work before you install a long block and romp on the happy pedal requires more than tools and the willingness to take on the work yourself. Same goes for any shop doing it on behalf of a customer. Any shop that doesnt take the time to measure, record and proceed properly with a build or install is no more than a parts changer. The world has enough of those.With the volume that any company like ATK or BluePrint does, there will be a small percentage of products that get missed or done with some margin of error. You do your job properly before you rush through to get it on the road or out the door and youll usually catch these issues. Then you can deal with the company about an unused, undamaged product and your position is stronger. Then they have the opportunity to 1) apologize, 2) pay the freight to send back the problem item, 3) expedite shipping of a replacement, 4) run the problem product back through processing and QA and return to stock if possible.I built my SP04 SBC short block with another companys budget 185cc aluminum heads (you have to go through those, too), GM roller lifters, Comp roller cam, Scorpion rockers, ARP fasteners everywhere, Holley intake, bored and machined TBI unit, 80# injectors and a modified ECM to tune it (myself). Distributor is same that GM uses on their RamJet engines, dist. gears are compatible, chose a Melling Select std volume/ hi pressure oil pump. Had no issues reusing the stock accessory brackets. Result is a 10.2:1 408 SAE gross HP engine thats been trouble free from day 1. The block is bored .040 over so its a 357 with stock 3.48 stroke. 45-48psi oil pressure at hot idle. SP04 includes moly rings, so get them seated properly and youll have no issues.

WORST PLACE EVER, don’t get an engine from them unless you won’t drive the car that much. I wasn’t able to read reviews before getting the engine because my mechanic recommended them and advance auto parts… got the 1st engine and it lasted 3 months when misfire came out, filed the claim and got the other engine, they did not cover the labor because it was already 3 months, so I was like no other choice, now with the 2nd engine the same issue misfire on cylinder 2 and 3 . Psi came down to 65. What type of parts are they using to rebuild this engines ??? Everything was done correctly when breaking down the engine, no more than 50 mph and rpms@ 2,000 . Didn’t load the truck. Nothing wrong was done from my side. 1st and 2nd engine the same!!! What’s next ? Who will pay for the extra expenses ? Don’t throw your money and time with atk!

Very bad Customer service. I bought a 360 magnum long block, Hp73. The moment I start it, the head gasket starts leaking. I call them, they said I could replace it and theyll reimburse me (which they never did) for doing it. Did that, started it then it starts knocking. The customer representative said to send it back. Which I did, then after a week he tried to say they found metal in the engine they built for me. Eventually he agreed to put new parts in and send it back, but I did receive it back and running. But the hoops I had to jump through wasnt worth it. Go somewhere else for an engine.

It isnt worth it dont do it it isnt worth it both Heads not tighten head gaskets Blue on StartupRan hotHad to have the heads taken in and redone after replacing the head gaskets againTry to file a claim and try to get a Nickelback right

Worst customer service! pray to god that you dont have a warranty claim! Eric is a real piece of work, never returned my calls untill I went over him and complained to his manager, then he finally returned my call. He was rude and defensive. Not help[ful at all. Buyer beware

Im glad i read the reviews before making a purchase. No way at all will i purchase anything from ATK. I will be sure to advise my friends, and people attending car shows to also not purchase from ATK. They dont even deserve one star.

Ordered a GM 5.7 marine crate engine 5/25/21 thru JEGS, a month and a half later now, made several attemps to get tracking info, finally after loads of explitives, they tell me they got ahold of ATK, and there is NO eta on delivery I am 32nd in line and they have 0 5.7 blocks available! Why in Gods name would I order an engine if I was told theres no eta on delivery? BECAUSE I WASNT TOLD! Ive been a certified Marine service tech for 20 years, never have I had issues like this. This is the first time Ive done business with JEGS and or ATK, and it will be the last time. DO NOT ORDER AN ENGINE FROM JEGS OR ATK YOU WILL NEVER GET IT! I cancelled the order, and they said the money will be credited back to my card, from my experience so far, I would bet it wont be that easy to retrieve it.

I purchased a block from ATK Engines back in May of 2018, I had some problems with the block. Contacted ATK, Brandon Simkiss approved the block for warranty return. Furthermore I dealt with Eric Smith, he was a great help! They assisted me with refund of my return shipping once it was inspected by their machinist. The whole process took about a month but it was well worth it. If I had to I would buy from ATK again, theyre reviews arent the best but in my case I was helped, and satisfied!

Lots of bad reviews, bought the 383 long block 4 years ago put 5k miles on it hit the rev limiter everytime it leaves the shop, so far so good!

The first long block (5.7 TBI Chevrolet) I received from them overheated in two miles if you pulled any sort of trailer. $500 in additional parts to prove my case and a couple dozen hours of experimenting later (keeping in mind literally every cooling part was new when the engine went in and I had the HD radiator), they did actually agree to replace it and paid my labor claim, so other than the time/downtime/PITA factor, I guess they did the right thing. The second engine seemed much better initially, but 4000 miles later, its clattering from the valve train like its got 200,000 miles on it. Im on my third valve adjustment, and it no longer makes any difference in the way it sounds. Used Penn break-in oil, so Im pretty sure improper cam break-in or lack of zinc wasnt the issue. Long story shorter : I give up. Im rebuilding an engine myself, like I should have done to begin with. Its a work truck and cannot be down. Sure wish either of the ATK engines had given me half the confidence of the 282,000 mile factory engine I took out of the truck.

Glad I read the reviews on these guys before I wasted my money

Bought a 2.0 ecotec motor and it runs perfect.

Worst customer service wait on the line 3 times for 45min a time and then they answer and hang up

ATK has a no fault warranty and stands behind it. As far as they can and its never their fault. Claim number WC 16200 . tried to work with them and they went behind our back and gave the owner a free replacement. The owner took it to a different shop to have it installed. We never got paid and were threatened with legal action . I could write a book about Ronnie and Stuwart in warranty. I am sorry to see ATK now supplies NAPA the rebuilt engines. NOT HERE NOT NEVER

WORST ENGINE EVER....RINGS NEVER SEAT ....ALWAYS ADDING A QUART EVERY TWO WEEKS ....TIMING CHAIN BROKE ....VALVE SEAT BROKE DAMAGED PISTON .....YOU WANT MAJOR TROUBLES .....NEVER EVER BUY FROM ATK ....

Ive never left a negative review for any product or establishment in my life. But ATK has performed so far below even the lowest of expectations, that I had to share my experience.Brand new 360, less than 100 miles. Chews up three distributors, then seizes completely. After an endless and horrible customer service experience, during which they made every excuse you could imagine, a new motor was sent out (took a year) and installed by qualified mechanic.Fast forward three years, and 100 MILES. Completely seized up.Customer service says, sorry, out of warranty.Terrible way to do business, and I would suggest shopping elsewhere.If only zero stars were an option.

Buyer Beware... ATK builds some of the cheapest, most unreliable engines on the market and warranty claims are almost always rejected.Save yourself the time and trouble and purchase from a reputable vendor.

I purchased a LC9 5.3 long block in November of 2018 and I just turned 10,000 miles. The motor runs great with no knocking when cold and very little oil consumption. Every 5.3 I have had uses a little oil, but this one is very nice.

I’ve had a horrible experience with this company. I purchased a long block straight six 4.0 liter ATK engine for my Jeep Wrangler from Engine Guy (now out of business) a couple years ago. I bought the engine for about $1700. After the first couple thousand miles the engine failed. I went through the warranty process and had my claim approved. The ATK representatives were impatient, rude and unprofessional. I had my local mechanic install the new replacement engine. When it was all said and done it costed me another $2000 to get the replacement engine installed. ATK sent a $700 check to reimburse me some of the labor stating it was all their warranty terms would cover.Well once again, after the first few thousand miles it failed. Developed a terrible knock. Now I’ve got my mechanic looking at it again and it will cost me $940 in labor for him to determine if it is a manufacturer error, and it’s going to cost me another $2000 to have a replacement installed. Now I have to go through this terrible claim process again and deal with these unpleasant people. After I finally got my claim started, I asked if they were willing to do anything for me because these fixes were costing me thousands of dollars all because of their faulty product. All they told me was their warranty terms would cover up to $50 per hour in labor and if I wasn’t willing to pay the rest, I’d have to go to civil court to get anything more from them. By the time I’m done with this claim, I’m going to be $6,640 into these engine replacements all because I chose to buy from ATK. Their products are unreliable pieces of garbage. If I have this engine replaced under ATK’s warranty it will be my third engine from ATK, and at this point I’m just expecting it to fail like the others.If you’re reading this, DO NOT PURCHASE ANYTHING FROM ATK. They should not be in the engine business, their products are unreliable and poorly made. I wish I would’ve know before I made my initial purchase.

Was about to order a 383 forged short block from ATK, until i read all these reviews, i guess you get what you pay for... i will have to look at others higher priced short blocks, but sounds like itll be cheaper in the long run, than the cheaper but bad quality ATK product

Paid top daller for an engine that I had to put a oil pump drive gear in. They failed to mention I would have to put some of the internals together my self.

Personally I have yet to use them, but definitely glad I read the reviews before I made a purchase!! Dealt with a company much like this called “car monkeys”After the purchase of a motor threw this company I decided to read the reviews. I tell you from experience, heed the bad reviews as a testament and proof you don’t want to be in that persons shoes because I didn’t heed the warning and got screwed with a piece of junk motor that was not only rusted so bad the nuts and bolts broke off of nearly every one I tried to take off but it had over 120k miles already on the motor!! They wouldn’t give me my money back and I’m left 1,400 in the hole with a motor that’s junk. So again, just please read the reviews you’re better off going to ams racing they are backed by BBB. And lastly if I can save anyone from the head ache of dealing with power torque! Do not use them either!!

Horrible Customer service and terrible inconsistent machine work i will never buy from them again.

Trash engines, flat out miss installed and dont stay together long. The builders give you the wrong info when putting it together not recommended for anyone ...they flat out lie to their customer

Researching stroker motors for my TJ.

Engine barely has 1 hour of idle time and already knocking. ATK won’t cover it under warranty. Machine work is sub-par and technician on the phone tried to convince me that a cam install is what would have caused the rod bearing to spin. Well cam was degreed in. So basically he is a full fledged idiot. Ive done cam swaps on 100s of LS motors and never had a problem. Good job ATK, youre customer service is trash, your engines are trash an you wouldnt even attempt to work with a customer who paid $4200 for an engine that was machined improperly. Buy a junkyard LS people, this company is absolute garbage. There are more internet complaints on them for poor quality work and spun bearings on their re-manufactured engines than I can recall. ATK=Garbage.

BUYER BEWARE!Purchased an HP99F crate 302W from these guys in April of 2018. It arrived and was installed no expense was spared because I wanted it to go off without a hitch. From day 1 it leaked oil out the front and rear main. After troubleshooting that the HEI was DOA finally got a new one from 3rd party seller (since ATK said they wouldn’t send one). Ran for about 10 miles then the real problems set in. After about 5 months of troublingshooting with both ATK, 3rd party supplier, and internet form still no resolution. Finally decided to just send the motor back and get my money back. Luckily I was able to.Moral of story ATK is a joke their tech support is literally 1 guy named Eric that handles everything and is hard to contact and will not follow up on. He is rude and unhelpful. I don’t know where they get these motors but save your money and get a junkyard motor. BUYER BEWARE!!!!!!

Ordered a 6.0 ls engine, installed heads, started the engine and it knocks. Come to find out, they deck milled the hell out of this piece of crap. Pistons come up above the deck, slammed into my valves. Trashed my new heads, and summit wont deal with it. They say contact atk, but atk is a joke. Stay far away from this crap ass company. Screw summit racing and atk, rip of bastards. Should have bought a used engine.

We purchased two 7.4L 454 marine blocks from ATK this year. We installed them after test running on the ground with no issues. 2 weeks later the customer advised he noticed a loss in power. We performed a compression test which revealed low compression. When we removed the engines and disassembled them, we found metal shavings in the oil pans. We collected the shavings and bagged them up to be shipped out for inspection by ATK along with the motors.We had to call numerous times in order to get an update, and each time the lady on the phone had no idea, and kept telling us the technician would call us with the results. A month later our Service Manager called demanding an update and once again they had no information for us. Finally Curtis called back saying we improperly cleaned items which caused the engine failures, and he had no idea of any bag containing metal shavings that we stapled to the crate. How convenient! Mind you we are a certified Mercruiser & Volvo Penta dealer that replaces 100s of motors a year, and have been in business for over 20 years. We have never had this issue in the past.Wish I had read these reviews before bringing them on as a vendor. Customer service was terrible, and the warranty is a scam in my opinion. STAY AWAY!!

Nothing but problems dealing with customer service getting the warranty through. Very inconsistent and nobody seems to know how to do their jobs. Screwed up basically every step of the process. Would not recommend, nor will I be buying anything else in the future.

Purchased an ATK GM 6.0 long block engine through RockAuto. While still under ATKs warranty the engine started making noise then wouldnt run. Opened a warranty claim then sent the long block back to them for inspection. They responded with abnormal combustion caused the failure and denied the claim. Their report never mentioned that a piston came apart (we retained a large chunk of the #8 piston skirt that was found in the oil pan on disassembly). When asked about that they stated that well, its STILL RELATED TO ABNORMAL COMBUSTION AND IS NOT A COVERED CLAIM. I will NEVER buy another ATK engine from them (and were a shop that buys at least 10-12 a year). Whats the use of offering a warranty if theyre going to deny claims with an excuse that simply cant be proven either way? Terrible customer service and too many excuses. Buyer beware.

Do not buy anything from these people. Had the same problem as the other review you seen on here. Purchased the motor installed the motor and cylinder 3 was leaking we returned the motor and they did ship us a new one but when it came time for their inspection they said there was nothing wrong with the engine. Clearly me and 3 technicians and the owner of the vehicle are not crazy we all seen it leaking we are a certified shop not some fly by night. Their product is garbage and so is their warranty. THEY HAVE NO WARRANTY. Do not send the motor back make them send out an adjuster to inspect it.

I ordered a 5.3 GM new motor from Jegs before thanksgiving and was told it would ship between 20th and 23rd and could expect delivery by 29th. I called Jegs later that week and they said it was back ordered and had no further information. I called Jegs on the 27th and they said the motor was In stock but would not ship until the 3 of December. After the reviews i cancelled my order. I cant believe that JEGS would use a shady company like ATK to buy there engines.

Do not buy an ATK motor. Google their reviews. I received this motor and the paint job was horrible. Bare metal in some spots. Had to repaint the whole block rather than going through a return process. This should’ve been a red flag. After around 200 miles the oil pan and front seal started leaking oil. I reached out to Summit and was informed to my surprise that warranty issues have to go directly through ATK. Ok. So I called them. Their “systems were down” (another good sign) so I had to call back. The woman on the phone was miserable and rude. She kept asking for a serial number I could not locate. “Somewhere near the bell housing.” What a convenient place to put it! I called summit back and they called ATK on my behalf. I received a call the next day which seemed positive at first but then went right back down the rabbit hole of this phantom serial number. I crawled under and went all over the car. Didn’t see anything. While doing so the rude gentleman on the phone was slinging comments at me. “It must have happened during the install. Seals just don’t leak like that.” “I don’t see why anyone who installs motors would paint over a serial number.” The guy that installed it runs a shop of 40 years. He has 30+ classics he built and installed motors in. Guess what. NONE OF THEM LEAK OIL. The serial number was painted over because it’s apparently it’s a sticker. A paper sticker. Really? Too cheap for a metal plate or engraving? There is a metal sticker on the motor that says “Mexico”. That deserves better quality than the serial number? If there is one and it’s on a paper sticker, it was painted over to fix the horrible paint job from the plant. ATK was of no help. They were rude and useless. Keep in mind if you buy one of these, you’re probably going to have problems. Summit does not keep records of serial numbers so it’s on you to find this sticker so you can get support from ATK. Just from my experience, I don’t think I would’ve gotten much out of them even if I had it. It seems like their angle is to find anything that helps them not tend to issues.

I recently bought the 383 stroker 415 hp. Motor . It actually dynoed at 430 hp . . Its been in my 41 plymouth truck for 2 months now . Absolutely no problems !!!!! I purchased a complete motor . I will definitely buy another! Great performance motor .

First 6.4 I got was Soo bad we wouldnt even install it, they machined factory pistons flat on a few, replaced one piston, cyl bores were all scored up. R they replaced, second one lasted 7k miles but over a year and they said it wasnt them because it later a year). Ive got pics of first engine If anyone want to see what they consider is remanufactured for $6000 dollars

Guys please dont buy an engine from this company. You would be better off buying an engine from a junk yard. I was talked into buying one. The first engine knock from day one. Told to put heavier oil in it. Final the engine came apart under warrenty. But I had to pay half the labor for the second engine to be installed. They sent me another engine this engine smokes bad when you first start it up. It has used about 5 qts of oil in 4256 miles.Their answer its ok. That they arent going to do anything about it. So if any of yall are at any car shows look for a 2004 murano that smokes like a freight train. Again stay away from these engines. Read all the reveiws Im not the only one that is having trouble with this engine.

These are junk do not buy. In the first 5 minutes bent a pushrod and lost 3 cylinders because of junk lifters.

Awesome engines. they really do stand behind their products!

Poor choice

On July, 15th 2015 I order HP40C Chevy 454 engine from ATK Performance. The engine was shipped about 8 weeks later on September 9th, 2015 directly to Sexton Automotive in Northport Alabama. The engine was installed into a 1970 Chevrolet Chevelle a few weeks later.After the Chevelle was returned, within the first few weeks, I noticed there were signs in my garage that the oil was leaking from the Chevelle. The leaking was minor but it appeared that oil was leaking from the rear of the HP40C engine. In November Sexton Automotive was contacted about examining the leak but would not be able to look at it right away so the Chevelle was placed in storage.In January of 2016 the Chevelle was taken back to Sexton Automotive. After examination it appeared that the engine was leaking oil from the rear main seal and to be fixed properly would require removing the transmission from the engine. Since this was a portion of the engine that ATK Performance had installed I contacted them prior to any work being performed. I spoke with Wes at ATK Performance about my concerns about the engine leaking and having to pay for substantial repairs to engine. Wes said he would contact me back about this and what could be done. I did not hear anything back from Wes or anyone else at ATK Performance and a few weeks later had Sexton Automotive Repair the engine.Sexton Automotive determined that the leak was coming from the rear main seal and the seal and gaskets used in the initial install by ATK Performance were a cheaper gasket. The gaskets were replaced and the Chevelle was in working order in March of 2016.I again got in touch with ATK Performance and spoke with Wes about my issues. Wes indicated that I should have contacted them before doing anything and that there were other ways to fix the problem without removing the transmission. Wes was very hostile about the subject even though I had contacted ATK Performance prior to doing any repairs and expected Wes to contact us. Although it was agreed that ATK Performance would pay for $350 of the repairs the cost was substantially higher.After the Chevelle was returned I have again noticed that oil is leaking from the rear of the engine. I have taken it back to Sexton Automotive. They have only examined the engine, but they are concerned that there are problems internal to the engine causing the leak to occur again. It is there opinion that there is likely a problem with the crankshaft and their suggestion was to return the engine to ATK Performance.I have been extremely disappointed with the HP40C Chevy 454 I received from ATK Performance as well as how they have acted about my concerns. I have had this engine for a little over 6 months and it has never been right. I have only driven the vehicle seldom since the engine was purchased and have not been able to enjoy my car. I was expecting an engine that had been tested and was checked properly before delivery. What I got was an engine that leaked oil from day one. I tried to be patient and wait for ATK Performance to contact me back after my problems but got no reply and had to contact ATK Performance myself. I feel that I have been wronged by ATK Performance and sold an engine that was not to the level I was promised.Do not buy any motor or automotive products from ATK. They do not stand behind their products.Butch Chandler

So far these guys have been great. I had an issue with an engine my dad had bought and they stood behind it and fixed the problem!

WARNING, DO NOT DEAL WITH ATK!Received a motor with low compression on one of the cylinders, did a leak down test to verify that the motor was no good. Received a replacement motor that worked okay but when the bad engine went back to ATK for inspection they claimed there were no problems with the engine and denied any warranty. DO NOT TRUST THIS COMPANY THEY WILL RIP YOU OFF!!

They ripped off the local mechanic where we do business not once but twice. I woudnt buy anything from these people.

Awful company. They build poor engines

Installed a 3.5l i5 gm cylinder head and one valve was ground down way to far and had the same cylinder have 0 compression. called tech and they will not pay labor so now i have to tell the customer he has to pay again and hope they fix it.

Wide and vast selection.

Trust me