AMC 401 teardown

guffey24

guffey24

Well-Known Member
Joined
Jun 7, 2006
Location
Hendersonville, NC
Alright guys yesterday when it was raining I took a couple of hours and carefully tore down my 401, to the bare block, I have everything labeled in boxes for reassembly

I have helped tearing down a few chevy's with dad some years ago, but this will be my first AMC, and I want it to be good the first time

patience and time, I have plenty

I snapped a few pics, and found some things in dissassembly

I am guessing the fuel pump needs replaced

View attachment apic19.picturetrail.com_VOL1077_4257543_8937564_234687387.jpg

The heads seem to be in good shape, havent really messed with them much

View attachment apic19.picturetrail.com_VOL1077_4257543_8937564_234687385.jpg

The block is in good shape, cylinder walls look very good, I will no more about them, after it is cleaned up

View attachment apic19.picturetrail.com_VOL1077_4257543_8937564_234687382.jpg

View attachment apic19.picturetrail.com_VOL1077_4257543_8937564_234690332.jpg

Several of the pistons have some chips out of them, this one being the worst, dont know where the pieces ended up

View attachment apic19.picturetrail.com_VOL1077_4257543_8937564_234690316.jpg

Timing cover has some spots, I am guessing, that was caused by the fuel pump falling apart

View attachment apic19.picturetrail.com_VOL1077_4257543_8937564_234690319.jpg
 
I am going to rebuild this thing myself

not the machine work

plans are to have the crank ground, hopefully use standard pistons, and upgrade the cam

any help would be apprecitated, whether it be advice or hands on

like I said earlier, this is going to be a slow process
 
Lots to address here.
Heads: At the very least have Vacuum pulled, and take them apart to check the springs and have new seals installed. At the same time have the surface checked for flatness, and check the guides. If you don't do a valve job I would at least lap the valves.
Timing chain cover should be Ok as long as no holes
Block will need to have bore checked to see how much wear.
Crank, only need to have it turned if it's out of spec.
Pistons look like mine did, after someone put ball bearings in my secondaries.
You will be putting new pistons in anyway so if you have to go 30 or 40 over isn't a big deal.
Any other info you need give me a hollar
 
I would be real concerned about valve clearance.
Either now or sometime in the past somethng has hit the piston, and given the location...
 
looks like it broke a timing chain at some point or it was VERY loose.

could be a result of other things, but that'd be my bet with the cover damage and piston damage.
 
I would clean and enlarge the oil drain back holes in the lifter valley, possibliy add extra ones. I would drill a smaller hole in the cam bushings to increase oil pressure on the rods & mains. Cross Drill the crank for improved oiling. I would most likely replace my timing cover with a new one if there was wear in the oil pump area-a switch to Davis Martins aluminum street gears for the oil pump. Modify the heads for Adjustable rockers with guides. Run L2380 F pistons from a '71 401 for the increased compression Of course have it balanced and some mild porting and bowl blending on the heads.
 
Man,
You need to find those rats that been eating pistons?
Bad case of spark knock could have started the breaking process . Ask that heads be tumbled when valve job is done. If core sand or slag is blocking water flow, that can cause a hot cylinder(s). I think Jasper in Greensboro area tumbles iron blocks and heads as part of cleaning process.

My $0.02 :beer:
 
If you haven't already, checkout bulltear. It was invaluable when I was rebuilding my 360. Also a good source for timing covers
 
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