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what exactly are they? i heard lots of good things bout them but never really looked intoi what they consist of? so iv heard they are just a 350 sbc with a 400 crank???

i think i threw a rod in my burban or spun a main bearing.? its nokcing like hard and thats why i think i snapped a rod... so is it just a 400 crank and if not what is it and is it worth doin since i have to put new rods in?

If the engine threw a rod you might want to look at the block real close. It probably has a BIG hole in it.

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The 400 crank has a larger main journal. The main has to be turned down to the 350 journal size. Also, you will need new pistons as the pin height is different. You can get a new cast crank for under $200.00 now that will bolt in, be sure to get the internal balance one so you can reuse your 350 flywheel and balancer. Pistons are cheap also, depending on the brank. Stay with the 5.7 rods and you won't need a small base circle cam.

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I didn't know that. I bought a chrome balnacer for a 400 and always thought Ihad to get an original 400 flywheel. I had the original crank though.

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You can get the 383 crank with either type balance. You just need to be sure which one you have and use the right one.

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the 383 s are great motors lots of torque and depending what you do lots of hp , you can buy a scat crank for around $200 , there is just a little extra exspense in the machine work end to clearence the block and rods , but no big deal you can do that your self if you wanted ,

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junkyard racing - we win with your old parts

You are better off to buy a whole kit, summit sells a good one. You'll need all the gaskets, freeze plugs, rings and bearings, etc. You'll need to have the block bored if you want a true 383. A 383 is with a .030 over block. .040 over will get you a 385. Also, you should have the block line-honed. The 350 blocks tend to "twist" a little bit when they were new, so when you rebuild them its best to line hone them to make sure the crank sits nice and true. You also need to have the crankcase clearanced a little bit for the longer stroke. That is something you can do yourself if you know what you are doing. In the end, you are looking at around $1000 minimum for a good strong engine. If you think that you threw a rod, you also need to have the block checked before you buy any rebuild parts and make sure that the cylinders aren't damaged beyond repair, and also to make sure that they aren't too worn to bore. Also, a lot of the time you open an engine up and find it has already been bored at one time, which means you may not be able to bore it again. Once the machinist says the block is good to go, have it bored BEFORE you buy your parts. I know a guy that bought .030 over pistons just to find out that the cylinders wouldn't clean up at .030 over and they had to go .040 over, but then he had pistons he couldn't use. I was about to order pistons for my engine, assuming that the engine had never been rebuilt. Then I decided to throw a mic on them just to make sure, and what'd you know, they were 4.030 pistons! So I had to go .040 over.

Good luck. If you have any doubts about what you are doing, get help. It sucks to waste all the time and money on an engine that doesn't run good or blows up after a few months.

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No LUV anymore, but still in the GM truck family. Running a lifted 2002 Silverado Z-71!

I took a block, crank and rods to my machinist yesterday to have them gone through for my rebuild. I was planning on doing a 383 if my 350 crank was beyond repair. When I said 383 he looked like he had just taken a huge bite out of a lemon. He explained that he didnt believe in a 383 for a number of reasons the main reason being there is a geometry issue that makes the pistons get pushed up the bore in an angle that eats rings. He also went off on a tangent about how un reliable they are. He said he is firm believer in a 377 (400 block 350 crank). I dont know if he was just trying to milk me into spending more money on his labor over buying new parts from Ohio Crank or if he was being totally honest. I have heard from another source how un reliable a 383 can be and lack of life span but didnt get any facts of why at the time. I know that a motor used in a high performance or racing application is going to be beat on and wont live forever but that is just what I heard yesterday.

I think he is full of it. My dad built a 383 for his chevelle several years ago (like 15). He drove it for 3 years before he wrecked the chevelle. Then he yanked the engine out of the chevelle and put it in a 70 3/4 ton pickup. He drove that for another year or two and it still had TONS of power. In the truck you really had to be pointed straight when you hit the gas or you ended up right back where you started. He sold the truck to a guy that was going to use it for a farm truck. He put some heavy duty overloads on it and a huge water tank in the bed of it to drive out to the pasture and fill water troughs for his animals. My dad still sees it occasionally driving around their little town and the same guy is still driving it and it is still the same engine. It has to have over 100k miles on it, since my dad put almost 60k on it before he sold it, and this other guy has been driving it for almost 10 years, with a heavy load on it almost constantly.

I don't know about the 377, I've never had any experience with one, but I know that with anything you build, if it is done correctly and you buy good quality parts, you will get a strong, reliable engine.

Obviously though, the way you treat an engine has a lot to do with how long it lasts. I know some people that swear by the 383. I think Summit claims that their kit makes somewhere around 400 hp and 450 ft lbs of torque. That is with headers, a good intake and a 4 barrel carb. That is basically a "stock" 383. If you add a radical cam, a little higher compression, some good heads, a good ignition and a good intake/carb combo you can easily see 500+ hp on pump gas. Its just not a very cheap way to go, but most things that make you go fast are expensive.

Maybe he was talking you into a 377 so you could see how hard it is to find a good SBC 400 block, and then he could sell you one he had laying around or something. Just my 2 cents. I think opinions vary about every engine ever made. Some people have good experiences and some have bad. I heard of a guy that put tons of money into a 350 and built it to run nitrous and blew it up the first time he took it out. I also read in Super chevy I think, where they took a junkyard 350 and put a new cam and carb on it to get it running good. Then they dynoed it stock, with a 50 shot, a 100 shot, etc to see how much juice it could take before it blew. I think at around a 400 shot of nitrous, it finally cracked a piston. A stock, cast piston with unknown number of miles on it. I think that run it dynoed somewhere near 800 hp, on a engine they picked up for $150 from the junkyard. If I remember correctly, it was a 2 bolt main even. So, I think every engine is different, and every builder is different and gets different results.

I totally agree with you about what you get for what you pay in most situations. I also do have some experiance with a 377 that ran on alcohol. He wasnt lying about it being a good motor either. As far as the 383 thing goes thats just his opinion and the opinion of someone else I talked to. If you build a motor out of good quality parts do all the regular necessary maintenance and pay attention to the tuning on a regular basis it should work good for a long time providing you dont do something stupid or have a freak problem. Like I said at the end of my last post thats just what the guy told me. I know a guy that bought a cheapo 383 from an autoparts store like 15 years ago roughly. He drives it like he stole it everywhere he goes and will let anyone who asks drive his truck and it still runs pretty good even though he doesnt take care of it or knows anything about it.

Hot Rod magazine had an article a few years ago about building a 500 ft/lb of torque 383 sbc. It didn't seem to be much of a headache.

If I had a good 350 block, I'd do the 383. The 400 block is expensive and the rods, pistons, etc. cost about the same so you'll spend less money that way.

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I don't know if it was just bad timing or what, but when I tried to find a "good" 400 block in souther Oregon a few years ago, I just about got laughed at by everybody I asked. It was similar to when I went to or called almost every junkyard in Oregon asking if they had any 65-66 Fastback mustangs. Most people said they had never had one, or hadn't had one in several years. I had a 74 GMC 4x4 that came with a SBC 400 that threw a rod right out of the side of the block and I was trying to put the same size engine back in it. Needless to say, it became the recipient of a hopped up 305 instead. I personally am going to spring for one of the newer generation engines next time I get a project. Something like an LS2. Summit has a LS2 crate engine from GMPP that comes setup for a carb. It is an aluminum block/heads, 6 bolt mains, .500/.500 cam, with 2.00/1.55 valves that throws down 440 hp and something like 475 ft-lbs of torque all for around $5k. I spent almost that much on my 350 for my Nova and I was probably around 400 hp but a helluva lot heavier than the all aluminum LS2.

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No LUV anymore, but still in the GM truck family. Running a lifted 2002 Silverado Z-71!

Have you checked SDPC for the same motor? I know they sell GMPP and have some decent prices for some stuff.

Stock 400 cranks came out of stock 400 block. The problem is that if people got the engine hot, it could and would crack between the water jackets in the block. Scratch one block. They did make 400 engines with 4 bold mains and steel cranks. Yes small block chevys... I have seen them and worked on them... I did, machine work, head work mostly, on engines on the in the 80's when truck mechanics were starving to death. I did work at a performance machine shop too, but most of those died when the play money died with the oil crunch too.

Life was a b i t ch in Houston back then....

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75 Luv, 350 V8, TH350, Camaro rearend. New 1975 Luv Step side. Stock for now.
Grandmaster of the "Shade Tree" way.. I can't see the yard for all the cars. Come on down and we will sit on the porch and watch the grass grow.

I've had a few of the 4 bolt 400's, got one now in fact. I prefer a 2 bolt as the webbing is stronger without the 2 extra holes. I usually just stud 'em. If there is gonna be a lotta NOS, I'll do the angles 4 bolt cap deal, but usually I just stud 'em. I have heard there were factory steel 400 cranks, but all I have ever found are the cast steel and if the 4 bolts have not been modded, a Nodular crank. Since I just race mine with no street miles I just grout 'em to the pump holes and spray the snot out of 'em. Doing it that way I can go .060...

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FIAA!

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I have no idea what the steal crank ones were out of, 4 bolt ones either. We just had a few "salvage" yard bring motors as cores. Wish I had put bought a few things and kept them. Like every thing else too. Even all my cars too.

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75 Luv, 350 V8, TH350, Camaro rearend. New 1975 Luv Step side. Stock for now.
Grandmaster of the "Shade Tree" way.. I can't see the yard for all the cars. Come on down and we will sit on the porch and watch the grass grow.

My 383 has 200+ passes, 500-700 street miles, and 80-100lbs of NOS run through it. It has NO oil pressure or reliablity problems, EVER. It has seen 7500-8000 rpms several times. However it does have a complete aftermarket rolling assembly. I would think that an unreliable or troubled 383 was a machine shop 383 and was not done correctly. Yes you have to clearence a little from the block to clear the rod bolts on some cylinders depending on year model block used. Mine is an externally balanced crank and yes you can get an internally balanced 3.75" stroke crank. These cranks are specially balanced with weight added to the journal instead of the counter weight of the first part of the crank.

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When I said 383 he looked like he had just taken a huge bite out of a lemon. He explained that he didnt believe in a 383 for a number of reasons the main reason being there is a geometry issue that makes the pistons get pushed up the bore in an angle that eats rings. He also went off on a tangent about how un reliable they are. He said he is firm believer in a 377 (400 block 350 crank).


Correct me if i'm wrong , but isn't the rod angle on a 383 is better than the rod angle on a factory 400 .