Glenbrook is an online mechanics writer, who enjoys rebuilding and modding classic Chrysler cars.
Affordable Small-Block Mopar Power
The Mopar 360 is the easiest and cheapest way to build a fast small-block Mopar. It makes more power than the 318 and it's a lot cheaper to build than a 340. It's also the easiest to find. After-market support for the 360 is great, and with the right parts, it can easily make 450 horsepower and still have great street manners. If you need more inches, it's easy to drop in a stroker crank and get 406 cubic inches.
Why Build a Mopar 360?
If you want an affordable high performance small-block Mopar, the 360 small block is your best choice. Parts and information are easy to find, and since it's a fairly popular engine, they are not too expensive.
Why is the 360 the best choice for a high performance small-block Mopar? Size and availability. The 318 is a great engine, but it gives up too many cubic inches in a purely performance application. The 340 makes an awesome performance engine, but it's rare, hard-to-find, and expensive. That leaves the 360.
The 340 does have a better performance reputation, but the 360 is actually a pretty good choice too. It offers 10 more cubic inches than the popular 350 Chevy, along with shaft-mounted rocker arms and a better rod ratio. Parts availability is almost as good as the small-block Chevy, if a little more expensive. It's pretty easy to get 400 HP from a Mopar 360 using mostly stock type parts. With the right modifications, you can get up to 500 HP on pump gas without nitrous or other power adders.
If you've never rebuilt one, How to Rebuild the Small-Block Mopar from SA Design has all the info you'll need. This book covers both the earlier LA series and later Magnum small blocks so it doesn't matter what style 360 you have. If you are only interested in the LA series engines, I actually prefer How to Rebuild Small-Block Mopar Engines from HP Books, but it's sometimes hard to find a copy at a reasonable price.
The Most-Cost Effective Modification
There's an old racing proverb that says, "there's no replacement for displacement." The easiest way to go faster is to build a bigger engine. In the past, this could be very expensive. However with the proliferation of low-cost, semi-custom parts, this is no longer always true. For example if the crankshaft in your 360 needs to be reground, it's almost just as cheap to by a new (cast) one from Eagle or Scat. Or maybe your stock crank is OK, but you want to upgrade to a forged crank. You can do so for only around $700.
In both cases, the stock stroke (3.58") crankshaft costs almost exactly the same as a stroked (4") crank that will turn your 360 into a 408 (assuming a 0.030 overbore). Besides the extra 48 cubic inches, the longer stroke pushes the pin further up on the piston. This gives you a couple of advantages. First, it reduces piston rock. This makes your engine quieter at start-up and helps reduce friction, making your engine last longer and helping it produce more power. Second, it shaves about 1/4" of solid aluminum of the top of the piston, making it lighter. For example, if you're using Keith Black pistons, the 408 package (piston and pin) is at least 23 grams lighter (almost 1 oz.) than the equivalent 360 package. This is dependent on application, in some instances the difference is substantially more.
About the only extra work you need to do to gain these advantages is a little block clearancing on the bottom end. That's it. Any competent machine shop should be able to do this for you. If you want more information about building big inch small block Mopars, you should check out How to Build Big-Inch Mopar Small Blocks. This book tells you everything you need to know.
360 vs. 340
In stock form, the 340 is a better performance engine. If built to the same specs though, the 360 will make at least as much power as the 340 at a lower RPM. The 360 is also easier (and a lot cheaper) to find. For racing, the 340 has more potential, but for street use the 360 is a better choice.
Hotrodding the 360
Like most American V8 engines, the Mopar 360 can make decent power using mostly stock parts. If you're serious about making lots of power with decent reliability though, there are some areas that should be tended to.
The stock Chrysler 360 crankshaft is cast iron and externally balanced. It's OK for moderate performance or light racing use, but if you're planning on making serious power it's better to go with an aftermarket forged crank. Both Eagle and Scat make reasonably priced forged crankshafts for the 360 (the Scat cranks are slightly more expensive but a better reputation for quality). Besides being stronger than the factory crankshaft, the aftermarket pieces are internally balanced so make sure to get the correct harmonic balancer and torque converter (or flywheel) to go with it.
The stock 360 connecting rods are OK for street use if have them Magnafluxed and checked for straightness, replace the rod bolts, and have them resized. By the time you do all that it's almost as cheap to go with a set of aftermarket connecting rods. The aftermarket rods are made out of better steel and they're also brand new. You know they haven't been abused by a previous owner. For me it's an easy choice. Up to around 450 horsepower the I beam rods are better (cheaper and lighter). If you're making more than 450 horsepower get the H beam rods (and send me your build recipe).
Pistons and Rings
The Mopar 360 never came from the factory in a high compression version. Factory pistons were cast and could have as much as -0.100 deck height, making for low compression and crappy efficiency. For a performance build, you should go with after market pistons with close to zero deck height. Use hypereutectic or forged, depending on intended power level. Using a piston design that uses 1/16" rings instead of the stock 5/64" reduces friction and gives you some free horse power. For pump gas, don't run over 9.5 compression with iron heads or 10.5 with aluminum heads unless you really know what you're doing.
There are almost as many opinions on camshaft selection as there are engine builders. When building a small block Mopar, the main thing to keep in mind is that most cam companies' "stocking" cam designs are likely optimized for the small block Chevy, and are unlikely to be the best choice for you Mopar. Make sure to work with an engine builder or cam grinder who is knowledgeable about what works best with the small block Chryslers. No matter what cam you run, you should upgrade to adjustable rocker arms. The stock, stamped rocker arms aren't adjustable and they cost you valve lift because they only have about 1.42 lift ratio instead of 1.5 as advertised. After market adjustable rocker arms have a true 1.5 ratio (they are also available in higher ratios) and offer adjustability. This is important even with a hydraulic can so that you can properly adjust lifter preload.
Intake Manifold and Carburetor
The Edelbock Performer RPM Air Gap is the best intake manifold for the Mopar 360. It's a lot taller than the stock intake, though, so be sure to check hood clearance. It works great with a Holley 750 vacuum secondary carburetor (3310 with secondary metering block installed). The stock 360 4-bbl intake is actually a pretty good piece too so if you're on a tight budget don't feel bad about running it. The only downsides is the weight - cast iron is a lot heavier than aluminum. Also, tuning parts for the factory Thermoquad can be hard to find. Of course, the ultimate setup would be a factory Six Pack - they're available brand new as a complete package for around $2000. In spite of being over 40 years old, the Six Pack runs almost as strong as the performer RPM and looks a lot better.
The 360's stock intake manifold and Thermoquad carburetor is actually a pretty good setup and can save you a lot of money over an aftermarket intake and carb. Back in the 1980s, Bob Lambeck was running 12 seconds in a 360 Duster equipped with the stock intake.The only downsides are the extra weight of the stock cast iron intake manifold and the difficulty of finding a decent Thermoquad carburetor. Personally I don't think the weight of the intake is a big deal on a streetcar, and you can find good re-manufactured TQ's for as little as $120 with a simple Google search, which is an outstanding deal - in fact I got one for the 360 build I have planned this summer.
The Final Word
The Mopar 360 can make an excellent performance engine. It was introduced with a 2-bbl carburetor in 1971. Not intended as a performance engine, it also featured a cast crankshaft and low compression ratio (8.5 to 1) cast pistons. When the 340 was discontinued in 1973, the 4 barrel induction was transferred to the 360 but the cast crank and low compression ratio remained. Quality control was also not exemplary during this time frame. That, combined with overly large main journals caused the 360 to gain a reputation for spinning bearings. In spite of this rocky start, the 360 can be built into an excellent street engine. All you need is attention to detail and proper selection of parts.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
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aaron barcelon on August 25, 2020:
Thank you sir for your great insight!!
MAC830203 on May 14, 2020:
Biggest issue in had going all out on a stroker 408 wasn’t parts. A bit pricey, but not bad. The issue was fighting with machine shops to get a block decked to the right height. I went with a magnum block but used the LA360 block height since magnum blocks are usually a bit high. It was .093 too high @ 9.678 vs 9.585 and a long fight with machine shops who wouldn’t take off the amount needed to get to a zero deck @ 9.599. When I finally found the right machine shop, the engine was perfect. Mock up the rotating Assy and get the decks right. It’s a critical step and not much attention is given. Some guy said the piston was supposed to be, “That far in the Hole”. Stroke/2+rod+comp height= X. After that it’s all valve clearance and quench height.
rick mcspadden on March 18, 2020:
1971 360 60/ 4;00crank displasment?
dominik on October 21, 2019:
we martin the la should bolt up if not you can get adapters but those will take power to turn and you will lose some power
Billy Heilman on October 15, 2019:
Whats the best oil to run in my 408 stroker
Wes Martin on September 26, 2019:
Have a '73 360 LA engine that I'd like to build and swap out with the 360 Magnum currently wasting space in my 1998 Ram 4x4. Not worried about motor swap, just can't seem to find any info on whether or not the LA will bolt up to the factory '98 auto trans. Any thoughts?
Jay R. on August 09, 2019:
No mention of heads. Any input for heads?
Eddie Levy on July 14, 2019:
I have a Stroker 408 engine, bored out CHRY 360. I wanted to idle the engine at most 850 rpm's but the engine, when in gear stalls below 1050 rpm's. I am seeking the answer to that.
bo bohannon on June 22, 2019:
Very food article, especially for me, as we are re-working the 360 in my newly acquired Lil Red Express.
Matt C on May 23, 2019:
Deck height and quench. If you’re going over 500hp aspirated, I was able to hit 600hp. But some changes too. I really liked the Quality and costs for Molnar Forged crank and H beam rods. I went with icon flat tops. They were very light and balanced out really well with little heavy metal. If you want to hit 400hp+, internally balanced is a must. My pistons were .042 in the hole. I wanted to get to 12:1 so the Magnum block needed decking. I’ve done a few now and if you race, there’s a huge difference between 600 hp peak and 7500RPMs. For a strong street engine, in a 4200Lb truck, I went with a 2600stall Hughes converter. A compact custom grind 1.6 roller 580lift and 290 Dur w/ 114LSA. Vacuums a bugger still. BnG has been great with the ECM
mods. Needed a Waldron 255 and 36Lb injectors on 93octane/99 race fuel. Looking injector set up to cool it down. It’s getting stupid now but, power under the hood is fun.
Grant zetterberg on April 24, 2019:
I have a 73 power wagon W100. I plan on doing a 408 build with the 360 LA. My question is. Will the 727 in it be able to hadle the power? It also has an np205 (divorced) with an 8 3/4 rear end. If the 727 wont work for that application will i be able to put a tremec T5 in it and keep the t case divorced?
Dennis Stafford on March 24, 2019:
Just finished my 5.9/360 Magnum short block , pulled the core from Pick a Part a year ago , 287,000mi , after tear down I found an all standard crank and cylinder's that still had the factory hone marks , at the machine shop the block , crank , rods & pistons were throughly cleaned and inspected , the block got a power hone and new distributor shaft bushing , I used a Seal Power Re-ring kit with Felpro gaskets, new blue printed stock oil pump Cloyes double row timing chain and gears , I also added a timing chain tensioner " highly recommended" The stock cam looked good , but if you don't know the Cam's in the Magnum engines are not just small they are tiny .400-.410 lift , new Cam's are $400+ , I sent my stock cam too Oregon Cam " Ken is Awesome" he re-ground my stock cam that is now .464/.481 lift " 1.7 rockers" 260/264 duration 112° LSA for $150. I'm putting the top end together now , Engine Quest heads with bronze valve guides, 2.02 / 1.62 stainless valves , Hughes #1110 valve springs. Intake is a stock EFI Kegger intake modified with Volume Reducing Plates from Utawesome , also removed the center divider, did some mild porting mostly clean up to smooth things out, buttoned up the bottom plate with slightly shorter bolt's " stock bolt's are too long and is why the gasket blows, a couple of washer's on the stock bolt's will work" , 1&5/8 full length headers are going in along with a real duel exhaust with cross over , custom tune will be needed , I also plan to upgrade the injector's and ignition , This is a stock short block 9:1 compression , I've seen this same setup pull 425hp 450ftlbs on the Dyno , later a TorqueStorm Supercharger will be added , that will up the power well over 500hp and into 600ftlbs+, one hell of a street / tow engine.
Grant Wilson on July 04, 2018:
Awesome info! My 20 year old son is in the Navy currently assigned to the Harry S. Truman CVN75. His first vehicle is a 1998 Dodge Ram Sport and he loves it. He would like more power out of the engine and it has 243000 miles on it. It sounds pretty good and still runs relatively well. I am highly considering having the engine rebuilt and beefed up a bit. 400+ Hp would be awesome but I have no idea were to start or who to ask in the Houston Tx area that can affordably do this type of project. I would think other modifications would need to be done to accommodate the additional power. I have a budget of about $7000 and i would imagine that some magic could happen with that amount. Any suggestions would be greatly appreciated. Thanks Grant Wilson.
Scott on May 25, 2018:
what year did Mopar come out with the first 360 everybody says 71 well the one that I have the numbers are 1/30/70
june anthony on May 04, 2018:
why not use 11 to 1 piston
SGMDEe on May 01, 2018:
Bored out my 360 to a 408 and having a few problems - horrible vibration which I'm pretty sure is the torque converter but she's also running really really hot. Swapped out OEM radiator and fan for an electric and it didn't help. Any suggestions?
Clayton H on September 19, 2017:
Has anyone found a supercharger for a 360? All I found are prochargers....
Matt C on July 28, 2017:
Ok, after reading the full article, the 408 or 410 is tough to get right if you're going EFI. Some parts can swap but not if you want a good strong engine. John at Southeast Performance is just the best for any build. If you want a great engine and done right, call John. He will walk you through options and best solutions. And most importantly, keep you from buying the wrong parts! The Cam is THE issue with the 408. Some builders will recommend a high lift and low duration cams. This causes you to spend literally thousands to get the right valve train. If its EFI, expect to spend 400-1200 on computer changes to get your motor running perfect. When complete, the 408 stroker can be a Monster!
Ben H on January 22, 2017:
Does this only apply for the LA 360 or does this apply for the magnum 5.9 360 as well.
Thorn3686 on January 15, 2017:
I broke (destroyed) the 340 in my '72 Dodge Demon. I'm building a 360/429 motor with a forged striker assembly from Hughes Engines, strictly Mopar guys. Full roller streetable cam. 91 pump gas motor. Doing Holley fuel injection on it. Can't wait
Hemi Orange black graphics original paint. Coil over HDK front suspension. Coil over Freakride rear setup. Mini tubbed.
George on December 17, 2016:
Requesting site info, to buy a turn key 360 for my Plymouth. Equipped with a forged crankshaft, I beam rods, 9.5 compression, adjustable rocker arms, thermoquad carb, mopar cast aluminum valve covers, manual choke, and basic stock mopar parts. Seeking an engine to have a lopey idle with a 14-15" vacum. Looking for a gas pump engine that sounds good and able to drive distances or parades. Messages may also be sent to bluecutvalley2002 at yahoo. Happy to share with anyone what my future project currently looks like.
Pete on December 10, 2016:
I'm building a 78 AMC Pacer wagon that is set up for a v8, From factory. the car weighs in at 1900. i am in the market for a sb Mopar 360. your info will come in handy (thank you). With some modifications I'm running a tunnel ram duel quad set up. If my math calculations are correct,I should destroy most opponents and frighten woman & children.
chris on October 20, 2016:
1974 Plymouth fury iii with 360 great post
Jim on October 02, 2016:
Definitely very useful information, I am building a 2010 dodge charger with the early 80,s 360. Of course there's a crap load of mods but when it's done it will be a one of a kind. If anyone out there has made this swap email me with your recipe, any help to save time and money will be appreciated. @ firstname.lastname@example.org . Thanks for the posts!!
matt on September 11, 2016:
Definitely useful and well sourced info. I'm building a .030 over 360 for my 87 Dakota. Thanks to what I've learned from this article. I'll be going with the 408 stroker set up. Just bouncing between a proform aluminum carb and a six pack set up. I plan on making it a beast.
chuckjones on July 26, 2016:
thanks for all the information about rebuilding the 360 because I'm going to be one and it will be my first timeI'll take pictures of it and keep all the information to let you know how the performance and my setup is thanks a lot
big ed on November 22, 2015:
on the strong 360 for the street mention above what are your head recomendations
dr.mopar on October 29, 2014:
360LA, Hands down the best steet/strip motor on the planet, .528 mopar solid lift cam, J-heads ported and polished, 9.5 street friendly compression, I beam rods, M1 single plan intake with a 750DP. Trans. 727 with a 4200 stall converter, 4.30 gear, M&H Dot wrinkle wall 28" tires, you better hang on, cause you just built a 12.5 second ride in a 3500lb car.. Have fun!!
Vegas10 on April 17, 2014:
Have a 1990 Ramcharger that is well on it's to being a real head turner but as we all know looks aren't everything. Currently has a stock 360-2 barrel which doesn't come close to giving me the power I not only want but need. I love my Mopar but this is a real dog that needs major league help. Could use your suggestions..stay with the 360 and rebuild, go big block, go with a new crate engine...I know, the possibilities seem endless. Thanks, Billeir1@aol.com
CampingmanNW on November 13, 2013:
413 was the Mopar for me. I put that engine in a 1953 Ford F-150. There were only two things that Truck would not do when I finished. One, accelerate straight down the road and pass a gas station. Thanks for a fun look back.
kyle-d-redman on November 01, 2013:
please emai me at email@example.com im about to rebuild a 360 and put it in my 85 dodge power ram truck in place of the 318 that's in it.........i was wondering if a holley 650 would work on the thermoquad manifold?
anonymous on July 31, 2013:
@anonymous: We are building a 1918 Dodge Brothers roadster with a 360,can't find streetrod headers.
anonymous on July 16, 2012:
need that to put in my 38 y old citroen 2cv
anonymous on April 06, 2012:
Hi Roy nice post, I am 3rd generation mopar, My dad and I built a 1915 Dodge brothers roadster candy apple purple w/ 360 it moves like nobody's business, we have always used TQ's if we could get them, I have 3 in good condition stockpiled back. my oldest son is building his first 360. well enough rambling just wanted to say nice read hear.
glenbrook (author) on March 24, 2012:
@anonymous: Hi Roy,
I got my Thermoquad from an outfit in Texas called AAAA Automotive. My guest book won't accept html but I put a link above under Stock Intake Manifold. You can also call them at (903)546-0024. They're open M-F, 8-5 central time. They're friendly and ship fast.
anonymous on March 24, 2012:
would like to know where you got the thermoquad carb ?great info
Tradeshowhobo on February 17, 2012:
Great lens. thanks.
tdove on July 20, 2009:
Thanks for joining G Rated Lense Factory!
Tonie Cook from USA on July 09, 2009:
I remember the Mopar. Nice lens.
Suzie-Shine on July 09, 2009:
It's all way beyond me! But sure it's of value to others.
norma-holt on July 07, 2009:
Well constructed lens with heaps of info for the enthusiast. Well done