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400 vs 350?

modhunt

modhunt

The CK5's Designated Toddler
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Joined
Feb 12, 2018
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Location
Lorton, Virginia
so I’ve read a lot on this recently and heard complaints about heat etc. I know the 400 makes more base than a 350 and I can use most of my current parts on it. It’s for a daily driver that sees mud once or twice a week what do you guys think on this a lot of you seem very knowledgeable on the old squares and just wanted to see yalls take on it
 
I would not try for this. You are too new and too budget minded. You need to keep it simple and get your truck running.
 
If you have both a 400 and a 350 laying around, to me its a no brainer, tear down the 400 and yank the crank out of it, and throw it in the 350...but that's just me :D
 
400 is a fine engine, but it is less forgiving than a 350 when it comes to coolant temps. As long as the cooling system as a whole is in good shape, you should be fine.
 
I had a 400 SB from a '78 K10 Suburban..put it in my '77 GMC K2500,when its 454 started making scary wrist pin noises..

The 400 felt just as powerful as the '74 454 it had before,and weighed less..I liked the engine,but knew about their reputation for overheating easily,and sometimes cracking ,since the cylinders are "siamesed" and have no coolant passages between the two in the center...

However,despite me overheating mine many times until I figured out why,found out no thermostat was in it,plus my plow blocked the air flow thru the grille enough to let it boil over at speeds over 40 mph if I drove more than 5-10 miles,until I found out you can lock the fan clutch to stay "on" constantly,despite all that,it never blew a head gasket, or showed any ill effects,but I'm probably the only lucky one that didn't have those problems..

Today I'd pass on a 400 small block,after seeing several others friends had that were just a pain in the butt--one had cam bearing issues,the block "warped" enough to bind up the camshaft,another one cracked between the center cylinders a few weeks after a rebuild (was bored out .030 over ),and another one died because whoever installed it used the flex plate and harmonic balancer off the 350 it was replacing,and the 400 requires a special externally balanced flex plate and balancer...it wiped out the bearings in a few days..

They still sell for good money,many guys like them--but a 350 with a 400 crank in it makes a 383,and its a very strong runner,with none of the cooling issues..
 
I'd find a stock 350 and throw it in. I have one sitting in my garage I bought for 300 bucks that I heard run, know the truck it came out of, and is 100% complete. There are deals out there, just be patient.
 
I have a 400sb in my K30 because it came with it so I did my own research as well as talking to my builder and machinist and basically they are prone to cracking between the siames cylinders in the center from the large bore size in the event of overheating. Apparently they are only prone to over heating if the stock heads are replace with different that are not drilled for the steam jackets. Supposedly they perform great though and accept most sbc parts.
They are however externally balanced, which is part of the reason mine isn't being driven yet as it's got an unbalanced flex plate that I just picked up a proper replacement for for 19$.
If you have one use it!
 
Kay86K5 said:
If you have both a 400 and a 350 laying around, to me its a no brainer, tear down the 400 and yank the crank out of it, and throw it in the 350...but that's just me :D
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My 350 has a cracked block and no 350s or blocks alone around me that aren’t super pricey or in good condition I was thinking about buying the 400 for $300
 
swettysblazer said:
I'd find a stock 350 and throw it in. I have one sitting in my garage I bought for 300 bucks that I heard run, know the truck it came out of, and is 100% complete. There are deals out there, just be patient.
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If you run into another could we come to a deal possibly I’ll pay shipping?
 
350's are around, you need to be patient and look around on various FB classified pages, Offer up, Craigslist etc.
 
skunked said:
350's are around, you need to be patient and look around on various FB classified pages, Offer up, Craigslist etc.
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Trust me I have no one with in a 2 hour drive or so has a block as a complete stock motor. The 350s I found all are built engines and people are wanting 3k+ for them
 
Abusfullofnuns said:
I’d bet my first born that this is not true. There are definitely deals to be had. It might take more than a day of searching.
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I’ve been looking for a bit and anything that is within price range is almost a 2+ Hour drive there and another 2 back and I don’t think I’ll have time to make that drive anytime soon with work and school
 
Look longer and harder and all over. I never subscribe to the thought of "there are no deals around me"...means you haven't looked hard enough and for long enough. Don't just jump into a situation that probably won't net you what you want/need, you will always regret it down the road.
 
Kay86K5 said:
Look longer and harder and all over. I never subscribe to the thought of "there are no deals around me"...means you haven't looked hard enough and for long enough. Don't just jump into a situation that probably won't net you what you want/need, you will always regret it down the road.
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Yeah looking at it now I am kinda being an idiot and impatient I hope y’all can understand I just really want to be able to have my baby back
 
What source are you using to make the comment about no deals around? If you are relying on something like Craigslist that is the problem. Only a fraction of the people with engines, or any other used parts for that matter, to sell actually use sites like that. I have a hard time believing there are no junkyards, engine recyclers, or mechanic shops around that don't have a used 350 engine laying around or know where one is. Also open up the search to complete vehicles. Always seems to be some old truck with a good engine that is either rusted out, wrecked, or something like a bad transmission.
 
modhunt said:
Yeah looking at it now I am kinda being an idiot and impatient I hope y’all can understand I just really want to be able to have my baby back
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Yeah we also know that being patient can save money.

Remember this is a group of idiots that will spend 10k on a $2k truck
 
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