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Valve cover tag 401.. Decode..?? |
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BrotherBamc
Supporter of TheAMCForum Joined: Jan/22/2009 Location: Lewiston Status: Offline Points: 2248 |
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Posted: Nov/12/2018 at 8:01am |
Drug home another 401 yesterday and I need a little help with the valve cover code. From what I can read from Eddie Stakes site is that this is a 73..?? The guy I got it from had already torn it down to inspect it. Which is kind of a bummer, but it is what it is. When I got it home and was able to flip it over and inspect the crank we've got a few nicks in it. I have no information of what this motor originally was in or came out of. The guy I got it from didn't know. He was going to use it in his son's car 74 Javelin that has the original 304/904 combo. Son now wants a S.B.C. instead of the 401. Other then the nicks in the crank, it's an original bore motor. But one thing that has me confused is that it looks like it might have aftermarket connecting rod bolts. The rod bolts are 24 point and not the standard 6 point. Looks like the main bearings are dated 72. Also the heads are bridged 502's. I thought that those didn't come out until later years. Anyways, it was a good day for a drive and I now have a few extra parts for the "just in case". |
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Late 73 will be bridged if early 74 model year... 08 will be just that as It was built after July 73.
Looks to be stock as nothing you have stated points to any other mods. The nicks look like a factory defect that could be cast bubbles. A guy showed me a broken crank journal with a 1/8 oblong bubble in it. All forgings come from poured steel slugs, formed, and then stamped in the forger before being machined. As for SBC over 401... only if you cheap out and get a complete engine and trannie combo for a quick swap and go. Rebuild the stock trannie with HD components for drag use, and mate it to the 401 with a proper flex plate, I don't think he'll complain unless he ends up having to pay for gas and tires more than he likes. As the setup is pretty quick with the right gearing. Look for 3.33 or 3.25 Jeep gears and a good limited slip to upgrade to. Edited by 304-dude - Nov/12/2018 at 8:24am |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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PROSTOCKTOM
Supporter of TheAMCForum Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2458 |
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All 390/401 engines came factory with 12-point nuts. For what it's worth I've never seen a 24-point nut. Here's a photo of a stock 401 I took out of an International pickup. You will notice the same 12-point nuts. Tom
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ccowx
AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510 |
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I think it is August 2nd, 1975.
Chris |
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7969 |
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ccowx
AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510 |
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My understanding of date codes is that the first number ie 6, is the year of casting of that block. My 1970 390 was cast in 1969, giving it a first digit of 2, since 390 blocks were in their second year of casting. If the same is true for a 401, I would think that they began casting them in 1970, so a 6 would be 1975. I am basing my assumption on what I know of the earlier motors, so maybe I am falling into the "assumption" trap!
Chris |
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7969 |
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Sonic silver is correct, my 71 has a 4.
Yes 6 is for 73, but the engine can be made a week before body. The month is August as for the 08 being stamped. Even though it Is a 73 built engine, it is destined for early 74 builds. So the engine would have come from one of the 1st run of cars on the line, for 74. Where is 401matcoupe when you need him? Edited by 304-dude - Nov/12/2018 at 11:14am |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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ccowx
AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510 |
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I am probably wrong, as is often the case! My engine block was cast on August 1st 69. Being a very early 70 that makes sense. Where my confusion comes in is that I thought that the date that you started counting from was based on the engine size. If that is the case, 68 as a starting point works for a 390, but it does not work for other displacements. 66 would be 1 if it was for AMC V8's in general.
Up front, I am probably wrong and I should know better than to assume! My attention has generally been on early cars and mainly 390's. I thought it was a predictable system, but it does not appear to be the case. Open mouth, insert foot! Chris |
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71SC360
AMC Addicted Charter Member Joined: Jun/29/2007 Location: East Tennessee Status: Offline Points: 5481 |
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Alex... you are correct! |
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