The Truth About The Small Block Chevy 400

rat marrow here and today i want to talk to you guys about the small block chevy 400 now this isn't really an engine that sees too much of the light of day not very many people know about it not very many videos out there on it but it's one of my favorite small blocks and there's plenty of reasons why so let's dive right into it [Applause] so what's so special about the small walk 400 the small block 400 was introduced in 1970 and carried out through 1980. this engine could be found in mid mid-sized cars such as impalas chevelles and larger sized trucks such as the k5 k10 k20 larger square bodies essentially from 73 to 80 could get this engine and it was available in cars until the end of 1976. so it is a little bit of a rarer engine than say a small block 350 which you know has been around for ever and has been produced forever so it is going to be a little bit of a harder engine to find and the main differences between a small block chevy 350 and a small block chevy 400 is the siamese bore that was used by gm to achieve the larger bore and stroke combination specifically larger bore combination with this larger bore the siamese setup essentially what it would do is there were no coolant patches in coolant passages in between the cylinders this allowed for the board to be much larger at 4.125 inches versus the small block chevy 350s 3.73 inches now what makes this pretty great is people usually have their 350 small blocks laying around and they want to build a 383 well how you build a 383 you actually use a small block chevy 400 crank that added stroke which is 3.75 versus the small block chevy 350s 3.48 basically lends you to have a stroker 350. now this is a super common engine swap for people this is super common build for people wanting to build small block chevys but the question is why aren't people using small block 400s the biggest consensus i've found why the small block chevy 400 is such an underrated engine is people have come to the consensus that these engines have overheating issues basically no matter what you do to them now that isn't true and that old adage has been gone through many times people believe that it's going to overheat instantly of a small block 400 it has a siamese bore there's no coolant passages in between the heads well the biggest thing that people do on these engines is they actually put aftermarket heads on it or they put you know better heads just from a different engine that's not a small block chevy 400 now you can swap any engine or any head you want onto these small block chevy 400s it's backwards compatible to pretty much anything else mine has camel humps from like a 70 camaro or a 69 camaro something like that the biggest issue though is people don't drill the steam holes in the heads now this is the biggest thing because the small block chevy 400 is a siamese four engine so there are steam ports that are actually drilled into the heads this factory 400 heads from from production that's how it is a lot of people don't add these or don't drill these steam passages into their heads very easy to do all you need to do is pull up a small block 400 gasket because that's what you're going to use on a small block chevy 400 you will line it up with the head and then you will drill the holes and i'll show you what those holes are supposed to look like right now now i have seen people get away with this with very good cooling setups without even having to drill the steam holes but the thing is you really should be adding them there's a reason that if you go and buy an aftermarket set of small block chevy heads that most manufacturers do have an option to include steam ports on the head already so yes it is a coolant it is a cooling function and it is mandatory i would recommend it no matter what if you have the heads off and you're doing that drill the steam ports because it's gonna save you some headaches down the road another big issue with these engines from the factory if you have a factory 400 and you're going to throw it in something it's still going to be the cylinder heads even if you have the stock ones stock cylinder heads are junk they are low compression they are smog arrow heads and they are very prone to crack so this engine pretty much got a bad rep from the factory instantly but that's not saying that we can't use the lower end of this engine the bottom end the fact that it's a 400 cubic inch small block we can still use all that we just have to make sure that the cooling system is up to the task and we have to make sure that the steam ports are drilled into the heads and if you have factory heads i'd recommend getting something different because they will crack now if you're looking to put one of these engines in your car or a truck or whatnot and you're going block hunting or you're going engine hunting there's three casting numbers that you can look for to identify a small block 400 that's 817 511 and 509 those would be the last three digits on the end of the casting number on the engine itself now the 511 block is going to be predominantly a four bolt main block there are some two bolt mains i have seen that are in a 511 casting those are super rare but the 511 block is going to be predominantly a four bolt main block and while you would be thinking wow i need to go out and look for one those engines actually are not as strong as the two bolt main variants of the small block chevy 400 now that's not to say that they're bad if you already have one go ahead and build it you're more than likely not going to run into any issues but when it comes to two volt blocks they have a slightly thicker main webbing and it does prevent cracking in the mains this engine over here in this corvette it's a four bolt main and it's been beat on for many years and i do know people that i've pushed these four bolt hands up to 700 horsepower with hard fill there's nothing necessarily wrong with it but if you want the strongest block possible the best option is finding a 509 or 817 casting that's in a 2 bolt main or if you find a 511 and 2 bolt main just very rare what you can do is you can get splayed main caps and convert it into a four bolt main which makes it much stronger than a standard four bolt main block that is if you're going for an all-out performance build that's how you're going to want to build one of these stock gm blocks now if you're not afraid to get your hands dirty a little find one of these old 400 blocks make sure if you're upgrading the heads which you should to actually drill the steam holes in the heads these are an amazing upgrade to a normal 350 that you could could be building instead and not to say that 350s are bad these just offer 50 more cubic inches right out of the gate and people have stroked these up to i believe 427 cubic inches 434 on a stock block so there's a lot more than just say a 383 that you can get out of a 350 by putting in a 400 crank and if you find one of these engines you don't have to get a stroker crank it's everything's already there you just bolt on a nice set of heads put in the camera you're choosing and here you can make 400 450 horsepower pretty easily now these 400s never being a performance engine they do not come with any forged internal assembly or anything like that it's all going to be cast so if you are wanting to go the big bucks route you can switch over to a forged internal setup and actually push these much further but the stock setup i've seen pushed anywhere from four to 500 horsepower so long as you're not spinning that cast rotating assembly too hard so why do i think that if you're trying to build a small block you should look for a small block chevy 400 because i see people spending thousands of dollars building a 383 when they can have that whole bottom end plus another say 20 cubic inches basically just searching around pick and pull searching around craigslist not having to completely rebuild the engine with brand new parts it is a cheap way to get more displacement i'm telling you it works incredibly well this is still a stock bottom end even pretty much stock 40 over pistons they're just cast pistons in that engine it was rebuilt at some point not by me and it runs very hard i've had zero issues within the fact any of the bottom end that's been no issues whatsoever i haven't had any issues with overheating the biggest thing to take into consideration here is that if you can't find a small black chevy 400 it is worth it to build that instead of 350. now you do have to pay a little bit more attention to the heads you have to get them make sure that the steam ports are actually drilled into the heads the cooling system has to be pretty decent but these engines do not have an issue with cooling when set up properly just the same as if you have a 350 it's gonna run the same as a 400 they're both small block chevys one set up a little bit differently just a lot of people unfortunately do not follow how you're supposed to actually set up the 400s to stay cool and what that leaves for us is for the people that hate the small block chevy 400 that leaves them out of the question but for us it leaves us with a diamond in the rough that can be found for decently cheap and a hell of a lot cheaper than building a 383 and just for fun i'll go ahead and throw in a video of my small block chevy 400 running in my corvette [Music] so now i hope this video was actually informational for you guys it's been a video i've been wanting to make for quite some time because a lot of people just don't know about the small block 400 and well that's been helping me out find some extra engines or you know helping other people out that know about it a lot of people don't know about it and i think it's important for people to realize that there's more options than dumping a bunch of money into a 350 to get that extra displacement not to say that 350s aren't good engines they are probably one of the best v8s of all time period and that's never going to change but if you're a hot rodder looking for a little extra cubic inches the small block 400 is an awesome option saves a little bit of money and well it just sounds cooler anyways guys if you guys like the video please comment like and subscribe and as always you guys have a great day

Channel: RatMaro

Views: 169,728

Keywords: SBC, SBC 400, Small Block Chevy, sbc350, sbc400, Chevrolet, Big block chevy, Junkyard sbc, Budget small block, bbc, Small block, Caprice, K10, K20, Camaro, Corvette

Id: 5VzWjxyNa1E

Length: 11min 20sec (680 seconds)

Published: Wed Apr 06 2022