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Valve cover tag 401.. Decode..??
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BrotherBamc View Drop Down
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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. Ouch







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". 
77 CJ5 360
73 Gremlin 401 4 speed
2006 Dodge Magnum R/T AWD
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304-dude View Drop Down
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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
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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Originally posted by BrotherBamc BrotherBamc wrote:

The rod bolts are 24 point and not the standard 6 point. 

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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I think it is August 2nd, 1975.

Chris
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Originally posted by ccowx ccowx wrote:

I think it is August 2nd, 1975.

Chris
Would be 1973, wouldn't it?
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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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Originally posted by ccowx ccowx wrote:

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
My understanding, and I could be wrong, is that my 70 AMX was built and delivered in Jan. 1970, is a 3. That would make year 1971 a 4, 1972 a 5, and 1973 a 6. I was under the impression that 1968 was year model 1.
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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
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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Points: 3510 		Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Nov/12/2018 at 11:48am
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!Embarrassed

Chris
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Originally posted by Sonic Silver Sonic Silver wrote:

My understanding, and I could be wrong, is that my 70 AMX was built and delivered in Jan. 1970, is a 3. That would make year 1971 a 4, 1972 a 5, and 1973 a 6. I was under the impression that 1968 was year model 1.


Alex... you are correct!
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