How large can a 413 block be safely bored?
#1925912
10/04/15 11:59 PM
10/04/15 11:59 PM
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Joined: Oct 2004
Posts: 1,074 So Cal, USA
Fab64
OP
super stock
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OP
super stock
Joined: Oct 2004
Posts: 1,074
So Cal, USA
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Hi all,
I recently ran across the following statement, regarding 413 blocks, from an anonymous user on a different forum. I am wondering if anyone can verify this information, specifically boring it out to a stock 440 bore:
"These engines were produced up until about 1973. I have always found them to have standard 440 LY rods (1851535), and 6-bolt cranks. The blocks in these engines were actually originally supposed to be 426's, (you can find the casting number 2658836 on the top rear of the block, near the oil pressure sending unit) and they were, in fact, "under-bored" .070 to 413 size (4.180). I have sonic-checked many of these blocks, and the cylinder walls are much thicker. So much, in fact, that you can bore these to a stock 440 bore (4.320) and still end up with the same cylinder wall thickness as a regular factory 440. There is considerable additional webbing along the outside of the block walls (where the freeze plugs go). The main saddles, supports, and main caps, however, are completely identical to a standard 440."
As always, I appreciate any information.
Roger
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Re: How large can a 413 block be safely bored?
[Re: Fab64]
#1925957
10/05/15 12:58 AM
10/05/15 12:58 AM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Dunno about that, the info I've seen does not support the claim the 413 and 426 blocks have the same casting numbers.
Cap designed changed for 74 MY blocks. Main saddle designed changed early vs late as well.
413's have a interesting history, early pass car stuff vs later industrial/HD truck useage.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: How large can a 413 block be safely bored?
[Re: Fab64]
#1926231
10/05/15 02:09 PM
10/05/15 02:09 PM
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Joined: Dec 2014
Posts: 5,777 ohio
ruderunner
master
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master
Joined: Dec 2014
Posts: 5,777
ohio
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Unless they used 440 molds for the late 413 you're not likely to be able to go to 440 bore
Angry white pureblood male
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Re: How large can a 413 block be safely bored?
[Re: 62maxwgn]
#1926280
10/05/15 03:02 PM
10/05/15 03:02 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Correct, there is just one 413 that shares a casting number with a 426 and it's an industrial engine, or it came in heavy duty trucks, meaning larger than a pickup truck. The chances of finding one are rather slim.
Here's the important point: The quote is referring ONLY to those blocks with that casting number. He is not talking about ANY OTHER 413 block.
Now that ultrasonic thickness testers are common, we are discovering how bad the Mopar blocks really were. It's a fact. Also, we're discovering that cylinder wall thicknesses could be all over the map in the same block.
IMHO the largest a 413 block could be bored to is 4.250. The blocks have such a low value that if one is bad you can always do another, although the price of boring another 8 holes may be more than the price of a sonic check.
R.
Last edited by dogdays; 10/05/15 03:10 PM.
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