Ok, here's the debate of the century: 383 or 400 chevy!! Cast your vote and reason - Page 3 - Hot Rod Forum : Hotrodders Bulletin Board
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View Poll Results: What's the better motor?
400 SBC 214 45.63%
383 SBC 160 34.12%
Bore your 383, get a 388 22 4.69%
They're equally good street motors 73 15.57%
Voters: 469. You may not vote on this poll

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  #31 (permalink)  
Old 02-06-2004, 01:52 AM
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ground cranks are not weaker, that's a wives tale. Weakness has to do with the radius of the crank, so the crank can actually be stronger after being ground because the radius is greater.

K

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  #32 (permalink)  
Old 02-06-2004, 07:46 AM
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Your kidding aren't you?
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  #33 (permalink)  
Old 02-06-2004, 08:48 AM
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Hey Guys, didn't meant to ruffle any feathers here. It was just my opinion. I've have three of em built for me and after tearing the bottem end out of the first two, and cracking the siamesed sections on the last one, I don't have a high reguard for them. As far as the hole, Or should I say "Holes" go, I guess he didn't know you could drill them out because it took him forever to find new heads that had them....May all you current and future 400 uses not have the luck I had...............
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  #34 (permalink)  
Old 02-06-2004, 11:41 AM
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Quote:
Your kidding aren't you?
No, I'm not kidding, its true. Anybody who knows what they're talking about in machining will tell you that the crank always breaks at the edge where its radius of the rod journal meets the rest of the crank. Here's a link I think you need to read.



light reading

K
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  #35 (permalink)  
Old 02-06-2004, 01:10 PM
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CRANK

I don't mean to get cranky here, but killer is correct. We used to grind a lot of cranks and then have them rebuilt with chrome. So shinny they looked like mirrors. But the original 400 crank should have been better balanced. Thus everyone knew that if you built a 400 you spend the money for a GREAT balance job. Between the crank and the weak lower block STRUCTURE it was easy to blow these engines. The folks that make the after-market cranks can give you more details as to why you should change over to theirs.

It gets a little fuzzy here, for me, but the original specs called for a HIGHER thermostat on the 400 and thus the wives tall started that these engines ran TOO HOT. But I do believe it was to allow the radiator more cooling time.

hr41pearl
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  #36 (permalink)  
Old 02-06-2004, 02:19 PM
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in my (short lived) experience, every sbc400 ive seen needed a lot of tuning up and fixing pretty often. From what ive seen(granted i am only 18) they just dont seem to be worth it.
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  #37 (permalink)  
Old 02-06-2004, 02:35 PM
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Quote:
Originally posted by Tissue
in my (short lived) experience, every sbc400 ive seen needed a lot of tuning up and fixing pretty often. From what ive seen(granted i am only 18) they just dont seem to be worth it.

400 sb life span is generally very similar to a 350 especially if the 400 is built using 5.7" rods or longer. I don't think on can state that they need fixing more often.....what kinda repairs are you referring to. When built right they are very reliable engines. As for its required tuning, the 400sb need to more or less tuning that any other engine.
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  #38 (permalink)  
Old 02-06-2004, 04:49 PM
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Just from my experience.... I had a 350 in my 3200 lb camaro, and I came across a 400ci small block out of a 1977 c20 4wd pick up with 76,000 original miles. It was driven by and older man and there was no ring ridge and you could still see the original cross hatchings from the factory bore. It had a stock crank, stock rods, and stock pistons. I took everything off of the 350 and threw it onto the 400. Fuelie 2.02 heads, 234/244 .488 .510 lift cam, edelbrock performer intake, 750 carb. I drilled the steam holes into the heads. Also the 400 I believe came with 8.5 or 9 to one compression with 76cc heads. My heads are 64cc so it probably bumped the compression up to 9.5 to 10 to 1 compression . I used the same stock cooling system and the engine ran at the same tempurature as the 350. The torque of the 400 campared to the 350 was awesome and the 400 had the same pull in the top end or the rpm's as the 350. I admit, Im very hard on the gas and hard on my vehicles. I would rev this thing to 6000 rpms on a dayly basis and this is with an all stock bottom end. Im willing to bet money that it had 400+ ft lbs of torque too. It would smoke the tires off my car at 50 mph, with a slight dump of the clutch. It took 2 years of this abuse before the rod bearings let go, and I believe this was due to the poor rod ratio. SO my choice would be the 400 sbc. Go with a set of 5.7 or longer rods and you will have a strong motor. I never had any problem with the head gasket, I don't know why anyone would. I haven't played with the 383 yet. But I agree with the saying "theres no replacement for displacement". I still have my 350 so maybe ill play around with that this winter and see how the 383 works out, but for now....400ci, 400ci, 400ci.
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  #39 (permalink)  
Old 02-06-2004, 09:32 PM
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Killer,you kill me. Im not speaking of the radius,Im very aware of fracture and tear points,I think comparing a crank that was turned .030 with a radius and comparing it to a cut .200 externally balanced cast crank is like comparing apples to oranges. Do you really think a small diameter shaft is stronger than a large one both being radiused? I would think that would be so obvious. If you believe that so strongly,I would suggest using a small journal 327 block for your next 383 build,just Imagine the strength potential!
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  #40 (permalink)  
Old 02-06-2004, 09:57 PM
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dude, you missed the point completely. If you grind a crank the tapered area where the journal meets the rest of the crank has the opportunity to be greater, that was the point of the link and that area is referred to as the "radius" so yes, if the crank was cut it will be just as strong if not stronger than the stock crank.

K
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  #41 (permalink)  
Old 02-06-2004, 10:19 PM
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Quote:
Originally posted by rifraf
Killer,you kill me. Im not speaking of the radius,Im very aware of fracture and tear points,I think comparing a crank that was turned .030 with a radius and comparing it to a cut .200 externally balanced cast crank is like comparing apples to oranges. Do you really think a small diameter shaft is stronger than a large one both being radiused? I would think that would be so obvious. If you believe that so strongly,I would suggest using a small journal 327 block for your next 383 build,just Imagine the strength potential!

that was a good one.

i have a 406 in my ss monte carlo & it makes around 475 hp. it doesn't run hot, i haven't blown any head gaskets, & it runs like a bat out of hell. the 383 is a great small block, but just like every body else has said "there no replacement for displacement". i'm using a 4 bolt main block (that every bodies afraid of). all you need to do is use a good set of main STUDS. you can have the steam holes in the block plugged, but why in hell would you want to? not in a street engine anyways. i'm getting ready to put a 4340 steel crank & rods in it with a solid roller cam & turn it 7000-7500 rpm (if i have to). i've seen to mainly of these 406's turn high rpm's & last to be afraid of them. a friend of mine turned his 7200 rpm & went 6.30's down the 1/8 with a cast crank! the only draw back to a 400 if finding a good block. 2 or 4 bolt their both good, but can't find either one hardly anymore. the only thing i never liked about them is the cast cranks & short rods. but you can get a 5140 steel crank for $300. thats not a lot of cash when it comes to peace of mind.

yadda yadda yadda
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  #42 (permalink)  
Old 02-06-2004, 10:25 PM
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?? Well that was off subject 406. I have never once stated in this entire thread that the 383 was better than the 400. I also never said the 383 crank was better, all I am doing is defending the wives tales about the 383, just like you are doing for the 400 . My point, if you read, is that the 383 crank, even if it was once a 400 crank, is not weaker than a 400 crank just because the journals are smaller. If you don't understand that, talk to a machinist, because I've explained it as best I can and I know its true. As far as displacement is concerned, I doubt seriously that the 17 cubes really makes all the difference in the world either. I'm sure it makes some, but you'll make more difference with proper tuning and good parts than 17 cubes will promise you.

So yes, 406, it is a good one, and a true one. Read the posts and get your facts.

K
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  #43 (permalink)  
Old 02-06-2004, 10:47 PM
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I thought it was to figure which would be a better motor to build,you will never convince me that a equaly prepped 383 crank is as stronger than a 400 crank,that is my debating point,cubes vs a weakend crank 383,I would not think of sending a performance built 400 out of my shop without a radiused grind. Why would you do one and not the other? Did it ever cross your mind that GM was thinking about the structural integrity of an externally balanced longer stroke crank when they made the larger mains? You only have room for a limeted amount of radius anyway. Were we comparing a built 383 to a stock 400? If thats the case,I stand corrected. Sorry,but come on.
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  #44 (permalink)  
Old 02-06-2004, 11:04 PM
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I think its obvious that there are some myths surrounding these motors, a weak crank is one around the 383. Another thing I think is important to consider, is that the 400 was never designed to be a performance motor. That is why it bothers me to use one. Siamesed walls aren't done because its optimal, they did it as a sacrifice and it ended up working out ok. I'm looking for people who can debunk rumors about hese motors and shed light. People are going to have to put their "I've heard" sayings aside and stick with truths. The truth is the block design of a 400 is inferior to other smallblock engines and that is why people are scared to use them. Siamesed walls are inferior to non siamesed walls. That is a fact, otherwise all the other small-block motors would have used them too. The question is whether it maters or not. From what I've heard, saying that there are "absolutely no" cooling issues in a 400 when compairing to other small-block motors is simply not true. Again, from what we've heard here it doesn't seem to be a big problem, but anything that has more cubes stock is going to generate more heat, and its something a wise builder would consider before completing his 400sbc.

K
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Old 02-06-2004, 11:53 PM
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I used to be the guy afraid of the 400,I felt my reputation weighed in the risk of building them,well,years went by and from first observing the faults and gains of others,it became my conclusion that they are one fine motor to build. There are some inadiqucies with them though,they do better with longer rods and of course,the heads suck,and not air,and due to the larger bearing diameter I like to run a standard presure big block oil pump and big pan,good bolts,balance bla bla bla. They wont spin as high as a 350 but without anything too exotic they do 6000 easy with a lot of power all the way there. For bang for your buck,you would be hard pressed to top one for a foundation in the street/strip sb catagory. Reliabilaty and heat has never been any more an issue than 350s ones Ive done,but I dont do em stock.
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