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AMC block casting dates

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captscot View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote captscot Quote  Post ReplyReply Direct Link To This Post Topic: AMC block casting dates
    Posted: Apr/14/2017 at 4:44pm
Someone on Ebay has a 401 block for sale. He identifies the block's casting date by numbers in the rocker valley in the front end of the block. Numbers are 238 which he translates into February 3, 1978. I am the original owner of my 1972 Javelin which came with a 304. I replaced the 304 with a 401. Still have the 304. The numbers in the 401 rocker valley is 243. Ok, I guess that translates into February 4, 1973, I can accept that. However, my 304, those numbers can't be correct if the decoding of casting date is correct. I bought my car in July 1972. From the build sheet the car was built in May 1972. However, the casting number on the 304 is 118. That's impossible because that translates into January 1, 1978, plus Jan 1 is New Year's Day, a holiday.

Do those casting numbers mean anything and how can you tell the date an AMC block was cast? Thanks, Scott

Edited by captscot - Apr/14/2017 at 4:49pm
1972 Javelin AMX - orig owner
1985 Grand Wagoneer
1967 Jeepster
1968 Jeep Gladiator
1959 Jeep CJ5
1929 Marmon model 68
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Apr/14/2017 at 5:02pm
The guy on Ebay is not correct in his interpretation of the numbers. That number is a Julian calendar number and is the 238th day of whatever year that engine was cast. Probably about early July would be my guess. There is also another number which gives the year, but it is usually the year that the engine was cast. For example, my 390 has a "2" for that, since it was cast in 1969, which was the 2nd year of the 390. I am not 100% sure how that would work for a 401, but probably starting in 1970 as the first year, since they would have begun casting 401's in the summer of 1970.

I hpe that helps!

Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bandana Quote  Post ReplyReply Direct Link To This Post Posted: Sep/13/2017 at 7:19pm
Going to open this thread again with a question - is there a casting and or build date on AMC blocks and if so where is it located?
I looked my block over today (its in the car) and all I can see is "401" in big numbers on either side of the block. How can I determine what year 401 it is?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2017 at 9:49am
Bandana,

The information you need is in my post above, and CaptScot's above that. The casting date is in the valley, which means you can not see it without removing the intake manifold. There will be a single digit number for the year and a three digit Julian calendar number, as pictured in the first post above. In the case of 390's the year for casting date is whatever year of manufacturer, ie 1969 is "2" because that was the second year of 390 production. I am not sure how that plays out for a 401, but likely they start number from 1970, since that is the first year they cast them.

Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bandana Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2017 at 10:23am
If that's the only place there is a code I guess it will be awhile before I find out. Can't see pulling the intake just for that. Thanks for the info.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote captscot Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2017 at 11:08am
If you can be sure your car has the original engine, or that the valve covers on your engine came with that engine, then the valve cover tag will give you the year, month and day your engine was built.  Refer to Eddie Stakes engine tag decoding guide.  On my original car, the tag confirms that my car was built May 8, 1972.   http://www.planethoustonamx.com/main/amc_valve_cover_id.htm
1972 Javelin AMX - orig owner
1985 Grand Wagoneer
1967 Jeepster
1968 Jeep Gladiator
1959 Jeep CJ5
1929 Marmon model 68
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bandana Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2017 at 12:27pm
I know my engine is not original and there is no tag on the valve cover. Its a 401 in a 70' AMX. The fellow that I bought the car from told me it was a 71' 401 motor, but he was wrong about a few other things on the car too so I thought I'd like to confirm what year it really is.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2017 at 3:06pm
Well, you may be in luck. The automatics have a different crank flange due to the changeover in 72 to the torquefligts. If it is a 401 bolted to a 1970 auto, more than likely it is a 1971 engine. Otherwise, you will likely need to pull the intake to be sure of year of manufacture.

Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote captscot Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2017 at 3:07pm
These guidelines I worked out may be helpful.  My '72 Javelin AMX came with a 304.  I am now finally converting it over to a 401, but want it to be accurate for 1972, features and casting numbers matching.  That means the harmonic balancer and pulley both need to be the three hole type.

Intake manifold number on a 390 is 3195532 C, two bolt holes don't align perfectly, 
but will fit on 401 heads.  Don't know the variety of '71 - '78 4bbl intake cast numbers.

Casting numbers
'71-'78  401 block is 3198951 located where the transmission bolts up (top)  

'70       390        heads 50.60cc is 3196291C  single rocker
'71       360/401 heads 50.60cc is 3196291C  single rocker
'71 late 360/401 heads 57.92cc is 3212993    single rocker
'72       360/401 heads 57.92cc is 3213948    single rocker
'73       360/401 heads 57.93cc is 3216090    single rocker
'74       360/401 heads 57.93cc is 3220502    bridged rocker

All above heads are dog-leg and use 1/2" head bolts

401 crankshaft casting no ('72 - '76 ring flanged, not sure about the others, maybe flat)
312-4725
319-0079
319-6921 - (1971)
319-6922
319-9842 - (1972 - 1976) ring flanged
321-4725 - (1972 - 1976) ring flanged   
322-0411 - (1972 - 1976) ring flanged
1972 Javelin AMX - orig owner
1985 Grand Wagoneer
1967 Jeepster
1968 Jeep Gladiator
1959 Jeep CJ5
1929 Marmon model 68
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Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2017 at 4:56pm
[QUOTE]  Intake manifold number on a 390 is 3195532 C, two bolt holes don't align perfectly, 
but will fit on 401 heads.  [QUOTE]

68 and 69 V8 intake manifolds have two bolts on each side in the middle that are in a different location than the later heads. FYI, a 70 390 has the same bolt hole locations on the intake as all 70 on up V8 intake manifolds
70 Javelin SST, second owner, purchased 1972
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