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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old January 30th, 2015, 06:26 PM
Vintage4WD Vintage4WD is offline
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Default Can anyone please help identify this 401 V6?

I have been working with someone to buy their 401 V6 engine... the year of the motor is unknown.

I've read the notes in Jolly's engine section, and my question is... are 401 Magnum engines stamped 401M on the block, or is the only way to identify the Magnum engine is by looking at the heads, intake, and exhaust?

Here are some pictures

Thanks for the help!





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Old January 30th, 2015, 08:44 PM
bigblockv6 bigblockv6 is offline
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Default Re: Can anyone please help identify this 401 V6?

For the most they are stamped with an M but not always as is the case of the one you have and it could be just the opposite. Ed Snyder bought a 401 with the M stamped yet it had the small port heads, this could be an issue with replacement engines rather than ones that came with the truck from the factory. The heads in pics are definitely Magnum heads judging by the intake ports and the larger size exhaust manifolds so your good. Look around for dates that can be cast on top of the back part of the intake manifold or the exhaust manifolds, if they're original to the engine then that will give you an idea of the year. From what it looks like to me this can be a 1968-71 engine, the breather is not on the left rear of the block rather it is plugged like all 68 up engines.
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Old February 1st, 2015, 09:22 AM
Rustbucket Rustbucket is offline
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Default Re: Can anyone please help identify this 401 V6?

The CL ad said the engine was rebuilt, but it looks like it has been sitting for a while. I would ask if he has receipts.
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Old February 2nd, 2015, 05:13 PM
Vintage4WD Vintage4WD is offline
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Default Re: Can anyone please help identify this 401 V6?

bigblock -
Thank you for the reply! I really appreciate the info!
Yes, with anything this old, its hard to tell what is original, and what has happended over time...
The engine in fact has been rebuilt, so possibly magnum heads were added at that time. I'm losing interest in this engine, so I may not pursue any further.
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Old February 2nd, 2015, 05:23 PM
Vintage4WD Vintage4WD is offline
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Default Re: Can anyone please help identify this 401 V6?

Quote:
Originally Posted by Rustbucket View Post
The CL ad said the engine was rebuilt, but it looks like it has been sitting for a while. I would ask if he has receipts.
Yes, seller says he drove the truck with the rebuilt engine to his house. But the engine has now sat for 12-15 years.

These 401s are cool and hard to come by, but I may decide to pass.

Thanks again very much for the lead and your advice!
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Old February 2nd, 2015, 05:29 PM
bigblockv6 bigblockv6 is offline
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Default Re: Can anyone please help identify this 401 V6?

If the engine turns over and is not frozen from exposure to moisture I wouldn't give up on it too soon, specially you can get it for a reasonable price. When I come across a used engine I usually do an inspection by pulling the heads off to see what condition the cylinder walls are, drop the pan and inspection the main and rod bearings. Though rebuild parts are getting scarce for the V6, pistons for the 401 are still available. Where in the bay area are you located?
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Old February 3rd, 2015, 04:28 AM
Vintage4WD Vintage4WD is offline
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Default Re: Can anyone please help identify this 401 V6?

Quote:
Originally Posted by bigblockv6 View Post
If the engine turns over and is not frozen from exposure to moisture I wouldn't give up on it too soon, specially you can get it for a reasonable price. When I come across a used engine I usually do an inspection by pulling the heads off to see what condition the cylinder walls are, drop the pan and inspection the main and rod bearings. Though rebuild parts are getting scarce for the V6, pistons for the 401 are still available. Where in the bay area are you located?
I'm in Pleasant Hill, near Walnut Creek...

The engine does turn over... I'm sure its an excellent motor for someone... and I did see info on piston availability... I simply have too many projects going right now... but I know its a rare and cool motor, and they don't come up all that often

I've asked the seller if he wants me to post his contact info here...
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