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what are some ways to identify a 400 smallblock
is there any colors
or codes to see if its a 400???
is there any colors
or codes to see if its a 400???
the 400 small block
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G
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·there are only 3 different 400's
block # 330817,3951509 and 3951511
the 509 and 511 blocks could come as a 2 bolt or a 4 bolt version
block # 330817,3951509 and 3951511
the 509 and 511 blocks could come as a 2 bolt or a 4 bolt version
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9,594 Posts
:withstupid:
A 400 has a harmonic balancer that is slightly larger in diameter than that of a 350 or the other small block Chevrolets, but that's pretty hard to spot or note by simply looking at an engine (read: nothing to compare the balancer to).
The 509 2-bolt blocks are the most desirable production small block Chevrolet blocks. There is a LOT of material in the main webbing of those blocks. They are about as strong as a GM Performance Parts Bowtie block...even with simply installing a set of quality main studs (ARP) and retainig the stock 2-bolt main caps. Several companies make splayed 4-bolt main caps conversions for small block Chevrolets. A 509 block with splayed 4-bolt main caps will easily take 1,000 horsepower.
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167 Posts
ok cause i know a old chevy graveyard and motors are laying everywere and i loved my 400 sb so identification # is the true way to find a 400.
they dont have a color or anything???
they dont have a color or anything???
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i was always told...
400 has 3 freeze plugs on the side of the block, the others only 2.
400 has 3 freeze plugs on the side of the block, the others only 2.
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167 Posts
i dont know about the freeze plugs but i do know
that the majority of them came with 2 barrel carbs
only a small few come with 4 barrel
if anyone has any other 400 identification methods plz share
thx
that the majority of them came with 2 barrel carbs
only a small few come with 4 barrel
if anyone has any other 400 identification methods plz share
thx
thats really about the only way to tell them apart by looking at them. unless your going to go there with a tooth brush and start cleaning off numbers on every block in the lot. thats how i found out what mine was i thought it was just a 350 and was like wtf is wrong with the harmonic balancer and a friend told me to look for 3 freeze plugs too
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Some 400s had 2 freeze plugs.
That "400s have 3 freeze plugs" is an old wives' tale. Well, more correctly, if you see a block that has 2 freeze plugs, that doesn't preclude it from being a 400.
The easiest external/visual thing to identify, if looking under the hood or otherwise at a complete small block Chevy longblock, is look at the harmonic balancer. 400s were externally balanced. As such, part of the harmonic balancer's outer ring will be "relieved" or, in simple terms, it will not be symmetric all the way around - part of the outer ring will have some material removed is missing for about 180 degrees of the circumference of the balancer. Look at this photo and perhaps you'll see what I'm referring to:
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That "400s have 3 freeze plugs" is an old wives' tale. Well, more correctly, if you see a block that has 2 freeze plugs, that doesn't preclude it from being a 400.
The easiest external/visual thing to identify, if looking under the hood or otherwise at a complete small block Chevy longblock, is look at the harmonic balancer. 400s were externally balanced. As such, part of the harmonic balancer's outer ring will be "relieved" or, in simple terms, it will not be symmetric all the way around - part of the outer ring will have some material removed is missing for about 180 degrees of the circumference of the balancer. Look at this photo and perhaps you'll see what I'm referring to:
G
Guest
·there's a 400 in the fs section that would be a reallllly good deal and ohio is not that bad of a drive to go get it
G
Guest
·note the 2 plugs in this one that is for sale in the other thread
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i see i see, :rotfl:
thx for the info
thx for the info
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9,594 Posts
One more thing about 400s:
IF it's known the engine is a 400 and it has 2 freeze plugs, it's a 2 bolt main cap block.
If it has 3 freeze plugs per side, it's a 4 bolt main block.
Once again, the 509 blocks are the most desirable and can fetch a good bit of $$$ if it is a good core and the seller knows what he/she has. They are stout blocks.
IF it's known the engine is a 400 and it has 2 freeze plugs, it's a 2 bolt main cap block.
If it has 3 freeze plugs per side, it's a 4 bolt main block.
Once again, the 509 blocks are the most desirable and can fetch a good bit of $$$ if it is a good core and the seller knows what he/she has. They are stout blocks.
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167 Posts
also whats better
2 bolt main or 4 bolt main
2 bolt main or 4 bolt main
Mine is the casting #330817, and is the 2 bolt block. Personally I would rather have a 2 bolt main block if I were building a mean motor because I would do spayed main caps. Thats the strongest you cang et, and I'm pretty sure you cant use them with a 4 bolt block. Mine also has the 8" weird looking balancer, and thats what I've always used to identify them. I wish someone would buy mine lol, my dodge and bike needs some lovin and gotta sell this motor to git-er-done! lol... 
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Further, to give you an idea of the kind of power that can be made with a 400 small block, fairly easily, when a wise combination is put together, simply do a Google search for "406 Chevy."
Chevy High Performance built a fairly basic 406 (small block 400 bored +.030") with a set of iron Vortec heads, Edelbrock Performer RPM Air Gap intake for the Vortec heads, relatively mild hydraulic flat tappet cam, 1-5/8" primary tube headers and a 750 cfm carb and it made something to the tune of 425 horsepower and 525 lb/ft of torque on 91 octane pump gas...both figures under 5000 rpm. IIRC, I think the engine was making somewhere in the vicinity of 470 lb/ft of torque in the 2500 rpm range. That is just about a perfect truck (low rpm grunter/torquer) engine. The only caveat to that being, with the particular combo referenced, the static compression ratio is higher than I'd recommend running (I think it was like 10:1 with those Vortec heads), which would require that premium/91 octane unleaded. Something more to the tune of 9:1 compression ratio would make a little less power but run fine on 87 octane pump gas.
Chevy High Performance built a fairly basic 406 (small block 400 bored +.030") with a set of iron Vortec heads, Edelbrock Performer RPM Air Gap intake for the Vortec heads, relatively mild hydraulic flat tappet cam, 1-5/8" primary tube headers and a 750 cfm carb and it made something to the tune of 425 horsepower and 525 lb/ft of torque on 91 octane pump gas...both figures under 5000 rpm. IIRC, I think the engine was making somewhere in the vicinity of 470 lb/ft of torque in the 2500 rpm range. That is just about a perfect truck (low rpm grunter/torquer) engine. The only caveat to that being, with the particular combo referenced, the static compression ratio is higher than I'd recommend running (I think it was like 10:1 with those Vortec heads), which would require that premium/91 octane unleaded. Something more to the tune of 9:1 compression ratio would make a little less power but run fine on 87 octane pump gas.
I put thin cc headgaskets on mine with the stock head, and a pretty lumpy hydraulic cam and 1.6 rockers in it with a stealth intake and a holley 800 spreadbore dp and a 3200-3400 stahl. That lil small block made my s-10 run WELL into the 12's with a 4.10 gear lol... I always guess/estimated it at 375-385 hp and roughly 400-450 lbft. Sure felt like it anyways lol...
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yeah 400 are sweet but they need lots of cooling
305s tho would a 305 with 350 heads make good power??
305s tho would a 305 with 350 heads make good power??
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A 400 doesn't need really any more cooling than a 350.
The key to building a 400 is making sure the heads are drilled for the steam holes in the block. Many companies, like AFR, have an option for said steam holes to be drilled by them when you purchase their heads.
If you're building a decent engine and the cooling system is borderline, be it a 305, 350, 400 or whatever, it's going to be a problem regardless of the engine.
350 heads on a 305 really isn't going to be such a hot setup. A 305 has a smaller bore than a 350 and as such, a set of heads from a 350 will have their chambers and valves somewhat shrouded by a 305's cylinder bores.
I think your concern about 400 cooling issues stems from the experience or opinion of guys that think 4-bolt blocks are superior to 2-bolt blocks, such as the basis for your question(s) earlier in this thread and that other thread you started specifically asking if a 2 bolt block or 4 bolt block is better.
The key to building a 400 is making sure the heads are drilled for the steam holes in the block. Many companies, like AFR, have an option for said steam holes to be drilled by them when you purchase their heads.
If you're building a decent engine and the cooling system is borderline, be it a 305, 350, 400 or whatever, it's going to be a problem regardless of the engine.
350 heads on a 305 really isn't going to be such a hot setup. A 305 has a smaller bore than a 350 and as such, a set of heads from a 350 will have their chambers and valves somewhat shrouded by a 305's cylinder bores.
I think your concern about 400 cooling issues stems from the experience or opinion of guys that think 4-bolt blocks are superior to 2-bolt blocks, such as the basis for your question(s) earlier in this thread and that other thread you started specifically asking if a 2 bolt block or 4 bolt block is better.
He's right once again lol. I never had a problem with this engine ever over heating. As a matter of fact, it always ran between 190-210 and that was best for it. I tried running it at 180-185 deg. and it ran like poo. Most people dont look at their head gaskets to make sure the steam holes are there. They think that all small block head gaskets are the same, well they are not. These do have steam holes, and gaskets dont always heve them, atleast thats what I always end up finding as their problem...
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