Found 401m??

[Gimmie1965]

Hey everyone. Found possible 401m today. Was one the way back home from visiting family over the weekend and decided to stop at a junkyard that I knew had some 305's. Found a late 60's to early 70's 6500. Not able to find anything on the block but was in a hurry to get home. The data sticker on the glove box said it came with a 401m. I'm going to be going down next weekend to do some more looking. Biggest ? Is is there something in particular I need to look for. The price is right so I'll probably be buying the motor no matter what. I appreciate all the info that you can give me

[Funky61]

Yeah check that engine block number to verify. I went to purchase a 351 and it turned out to be a 401M! Look for the trapezoidal carb mount on the intake too. Best of Luck

[Gimmie1965]

Thanks for the info funky61. There's a power steering pump mounted right off the tstat housin so it was difficult to see the stamping on the block. Going down sat to pull that off and get some pics

[Gimmie1965]

Ok so I went to today and verified that the motor I was looking at is a 401m. Sad part is that it is locked up. I put the trans in neutral and put a socket and long breaker bar on balancer and was not able to move it. For the price I think I'll still get it. Since the trans is still attached not able to verify that it has a 6 bolt crank. What's the chance it has something else or is there just the one crank style. It has a Clark 282v 5 speed in it. Not sure if that really maters as far as crank goes. Read several threads on gaskets but what I understand is that everything is same as 305 except for head , intake and exhaust. What about internal parts I.e. main and rod bearings and cam bearings. There is several listed on eBay but they are listing all v6 engines using the same. Very few actually say just 351 and 401. About what would it cost to rebuild the motor

[bigblockv6]

Some later 401 engines came with the 8 bolt crank too, you want the 6 bolt crank so you can use a 305 or 351 flywheel from a pickup truck. The good news is the 305, 351 and 401 engines all have the same stroke so you can use a crankshaft from a 305 or 351. The big difference is 305 and 351 crankshaft are cast Armasteel while the 401 crank is a forged. In a light duty application that should not pose a problem. That 401 appears to be locked up but doesn't necessarily mean it's the bottom end, moisture getting inside the cylinder bores from the intake or exhaust manifolds can build up a layer of rust in the cylinder walls then locking up the pistons.

[Gimmie1965]

I'm kinda hoping that's it. The motor is still in the truck. Its complete except only the base to the aircleaner is on. Ciuldnt find the rest of it. The radiator has been pulled but the top hose is still attached. Not sure about the lower hose. I don't remember it being there so it very well could be just rust in the cylinders. He also has another 401 laying in the dirt about 100ft behind the truck. It looks like it roll off the back of a truck going down the great lol. Good to know that cranks will interchange. I can get the 401m in the truck for 250. I might just get both. Surely he won't want more for the 401 sitting the dirt

[bigblockv6]

If I were you I would definitely get both 401 engines

[Funky61]

Wow; Got two in one yard! Nice score

[bigblockv6]

Originally Posted by bigblockv6

If I were you I would definitely get both 401 engines

The one laying on it's side appears to be a 60-65 non Magnum 401.

[Gimmie1965]

Yes the one laying on the ground is just a 401. I posted a pic of both block serial #'s. It has a 60-62 hydraulic bellhousing on it. Yes it was a good day as both finds lol. Also saw a 64-66 gmc 1000 series truck for sale as I was getting into town. It looked pretty clean but was only able to look at it thru the fence.