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Old 01-07-2007, 03:53 PM
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350 vs. 400 small block

although there is no substitute for cubes I've been hearing that the 400 small block is plagued with overheating problems because the cylinder walls are to thick. is this true?

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Old 01-07-2007, 03:58 PM
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Quote:
Originally Posted by penguinoitaliano
although there is no substitute for cubes I've been hearing that the 400 small block is plagued with overheating problems because the cylinder walls are to thick. is this true?

Too THIN it is said. Depends on who you talk to. Factory 400s were OK but were not high powered engines. I have seen many 400 performance engines with no problems whatsoever.

Right now the 400 block is so scarce that the 383 has come into favor and gives up only 23 cubes.
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Old 01-07-2007, 04:04 PM
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I've never had a heat problem with my 406. In fact it runs cooler than my old 350.
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Old 01-07-2007, 04:48 PM
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No, you heard wrong.
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Old 01-07-2007, 05:01 PM
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Quote:
Originally Posted by penguinoitaliano
although there is no substitute for cubes I've been hearing that the 400 small block is plagued with overheating problems because the cylinder walls are to thick. is this true?
you can only bore .40 over to be safe, but if you go to .60 over you will probably have problems because of the thin wall cylinders--so if boring the block, can you live with .20 over ???
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Old 01-07-2007, 08:16 PM
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Quote:
Originally Posted by handsome harv
you can only bore .40 over to be safe, but if you go to .60 over you will probably have problems because of the thin wall cylinders--so if boring the block, can you live with .20 over ???
We sonic test all the blocks that come in our shop and to take a guess at boring a 400 .040 over your flirting with disaster as we had 2 in the shop that were STD. bore and there is one cylinder in each block that is way to thin on the thrust side.

If it sonic tests fine it is a must to have it torque plate honed do to the big cylinders and and thin decks the cylinders distort more on the 400 blocks then the 350 blocks from what we have seen at our shop.
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Old 01-07-2007, 09:04 PM
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According to David Vizard, some 400 blocks will allow a great deal more than .60 over, but he says that 60 is all that is convenient.

He also mentions off setting the bores some toward the thick sides with the thinner walled blocks to allow for proper boring. He gives the tolerances in one of his books, but it's not in front of me at the moment.

Of course you have to sonic test to see what you have to work with.

He also mentions that a 2 bolt 400 block is a beefier cast than the 4 bolt. That amazed me.

I just bought my first 400 this afternoon, I can't wait to tear it down. It just has a minor rod knock. I may have to replace the crank since it was turned for the last time, but it's never been bored, so I'm interested to see what I have to work with. Wish me luck, peace.
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Old 01-07-2007, 09:54 PM
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i hear they are boring 400 smallies up to 454 cubic inches anyone also see these? based on a worlds products motown block. producing numbers to make the big block boys cry.
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Old 01-07-2007, 10:06 PM
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Quote:
Originally Posted by stewartcannon
i hear they are boring 400 smallies up to 454 cubic inches anyone also see these? based on a worlds products motown block. producing numbers to make the big block boys cry.

expensive aftermarket block
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Old 01-07-2007, 10:50 PM
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Quote:
Originally Posted by stewartcannon
i hear they are boring 400 smallies up to 454 cubic inches anyone also see these? based on a worlds products motown block. producing numbers to make the big block boys cry.
I have run a Dart block 454 small block since 2001.
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Old 01-07-2007, 10:51 PM
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Quote:
Originally Posted by Old School Baja
According to David Vizard, .......


He also mentions off setting the bores some toward the thick sides with the thinner walled blocks to allow for proper boring. He gives the tolerances in one of his books, but it's not in front of me at the moment.

.......He also mentions that a 2 bolt 400 block is a beefier cast than the 4 bolt. That amazed me.


It stands to reason that if the bore is worn .010 on the thrust side then a .030 cleanup would easily fix it (.015 from the bore centerline on each side). Overboring .060 with in this situation you could take .012 off that side instead of .015 (which is .030 from the bore centerline) therefore offseting the bore centerline a maximum of .018 toward the thick non-thrust side. That isn't much and lives within the head gasket limit. This is similar to offset grinding a crankshaft.

2 bolt 400 blocks are slightly thicker through the outer main webbing and are the preferred block, ideal for adding 4 bolt-splayed main caps which experts say makes them stronger than the factory 4 straight-bolt blocks. But hey, it is not like it is 1/2 inch thicker or something. The splaying of the outer bolts is actually stronger than the straight outer bolts on the factory 4 bolt, by design and by minor additional web thickness.
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Old 01-08-2007, 11:03 AM
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350 vs. 400 small block

Thanks for everyones input, it was very helpful. Just one more question. Is there such a thing as a hemi head for a small block, and if so can you direct me to the website. It's been fun reading all your comments.
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Old 01-08-2007, 11:56 AM
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Quote:
Originally Posted by penguinoitaliano
Thanks for everyones input, it was very helpful. Just one more question. Is there such a thing as a hemi head for a small block, and if so can you direct me to the website. It's been fun reading all your comments.
Not anymore. There was years ago. Mucho denaro...
Many excellent in line valve heads available today.
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