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Unread 01-16-2010, 09:26 AM   #1
Area.3.Fiftyone
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V8 identification help?

I found a J series truck in the salvage yard yesterday and was wondering if there was a definitive way of identifying the size of the engine?

The tag is still on the passenger side valve cover, but none of the numbers on it meant anything to me.

I looked on the sides of the block for a casting number that sometimes will tell the cubic inches, but this particular block didn't have any or I wasn't looking in the right place.

Any help would be appreciated.

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Unread 01-16-2010, 09:38 AM   #2
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Most of the AMC V8 "Crate" motors had the raised stamp engine size ground off the block. This is so the dealers could use one block and make it a 304, 360, or 401 as needed.
Between the raised stamp on the block, and the # on the passenger valve cover is about the only way I know of to tell engine size. Shy of pulling valve covers, heads, oil pans, and doing some precision measuring.
This may help with the numbers.
amc valve cover id
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Unread 01-16-2010, 10:03 AM   #3
jfwireless
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Here is a link to help you identify your engine by the date code tag on the valve cover

http://street2mud.com/webfiles/AMC%20Engine%20codes.pdf

There were replacement blocks made in the early 70's that came without engine size stamped on the side of the block. These were 390's with four bolt mains, and could be used to replace any of the AMC V8's at the time.

Also some dealers ground off the replacement block casting when they replaced an engine.

Jim
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Unread 01-16-2010, 10:20 AM   #4
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Man, wish I could stumble on to a junkyard crate 390... Not that we know that's what it is, but still. I NEVER get that lucky...
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Unread 01-16-2010, 11:30 AM   #5
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It would be a supper find if indeed at 390, good chance if no engine size casted on the block.

Stan let us know just how lucky you are?

Jim
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Unread 01-16-2010, 12:48 PM   #6
Area.3.Fiftyone
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I seem to remember the tag reading : 1 06 N xx

It looks like it's a 290? Is that a typo or did they really make a 290 cubic inch motor?

Never mind: it looks like it is in fact a 360

The N designation was only for early year 67-68 290's and they also used N for later model 360's.
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Unread 01-16-2010, 02:14 PM   #7
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Man I'm still kicking myself, cause before I got into CJs I found a 5 that someone transplanted a 401 in it - found this in the salvage yard. It got crushed a few weeks later with the motor in it
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Unread 01-17-2010, 08:30 AM   #8
jfwireless
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Quote:
Originally Posted by IronMaiden View Post
I seem to remember the tag reading : 1 06 N xx

It looks like it's a 290? Is that a typo or did they really make a 290 cubic inch motor?

Never mind: it looks like it is in fact a 360

The N designation was only for early year 67-68 290's and they also used N for later model 360's.
I am still intrigued by this engine, either the engine size casting was ground off, or maybe the original engine blew, and a new 390 short block was installed. The tag could be from the original 360.

Might be worth peaking into the oil pan and seeing of it has four bolt mains?

Jim
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Unread 01-17-2010, 11:54 AM   #9
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Quote:
Originally Posted by jfwireless View Post
There were replacement blocks made in the early 70's that came without engine size stamped on the side of the block. These were 390's with four bolt mains, and could be used to replace any of the AMC V8's at the time.
That block casting was chosen so that the engine could be used for racing since it would have met the mass production requirements. The SR motors themselved weren't all 390's. They were assembled to be whatever they were replacing since they had the wall thickness required to be bored to any of the displacement specs. A SR block may have been drilled for 4-bolt mains, but they would not spend money like that on a forged crank and 4-bolt caps for "Joe J-truck's" warranty motor replacment.
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Unread 01-17-2010, 08:16 PM   #10
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I read somewhere that the service replacement blocks were 390's, but here is what I found on a search tonigt, on multiple sites.:

An exception is the 1970 thick cast 360 used as a service replacement (SR block). This block could be bored and decked to build a 343, 360, 390, or 401. Dealers could therefore stock one part number to service four different engines. It can be identified by the lack of a displacement cast into the side. The casting number will be for a 401 engine. This block was used for racing as a thick walled 360, and in Trans-Am racing as a 5.0L. It MAY have been cast specifically for T/A racing at Mark Donohue's request for a heavy duty block, but because it carried a standard AMC part number and was available across the counter to anyone, it did not have to be homolgated like the "Duck Tail" spoiler. \

As I recall these blocks where all four bolt main, but could be bored and decked for any of the current AMC V8 engines.


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