I went wheeling on New Year's Day and was doing a lot of high RPM greasy hill climbing. I started noticing that at around 2200 to 2500 RPM that my 401 started clattering. My oil pressure started to drop to next to nothing once I got the nose up in the air. Once I was on flat ground again the oil pressure would rebound to 15-20 PSI. However, when I would get the RPM's up again even on flat ground it would clatter some. I had a couple of buddies tell me my motor was knciking and my rod and main bearing were done. I recently rebuilt the top end of this motor. Ported and polished heads, milled them and bumped compression to 10 to 1. I had the intake gasket matched and installed a torqy RV cam. The block had 66,000 on it when I built it and had excellent compression so I left the bottom end alone. I am pretty sure my oiling system is fine. Is this true, are my bearings likely done? Also, if so what would anyone recommend for doing to the bottom end of the motor to improve it. If bearings are done, then I don't want to just replace them. I would like to bore it and maybe deck, change pistons and balance. Any input on this motor would be greatly appreciated. I haven't been finding a lot of advice or info on how to make a sweet AMC motor. :(

Are you full of oil?

If the rod bearings were shot, you would get a knock all the time.

Yes, I checked the oil level. I even added an extra quart for the hills. I have some buddies that do this type of hillclimbing all the time and they said they run an extra quart because the AMC's oiling system isn't very good. I have had sevreal AMC's and none of them had real good oil pressure. Usually around 10 PSI when warm and idling or slightly above idle. It definitely doesn't knock all the time. I have driven a motor that had a rod knocking and it is definitely not the same. It almost seems like lifter knocking to me. It is weird, it is a higher pitched kind of clattering. ALmost like a cummins diesel. Like a bucket of bolts sound.

Does it do this on flat ground or does it only do it on a hill? If it is on a hill it sounds like all the oil is running away from the pick up tube. You could look for a deep sump pan or look into a baffled pan to help keep oil at the pick up tube on a an incline. Also you may want to recheck your lash on your valve springs and rocker arms. If it was lifters it would tick all the time.

Not sure about the oil pressure,but the clicking could be bent pushrods.We would bend them all the time in our race jeeps.The stock ones dont seem to handle much RPM.
Take them out and roll them on something flat(old window pane works well).
Here is a good place to start for AMC performance http://www.bulltear.com
OlyWa

Once upon a time, when I was looking for a 401, I found a site with (what I thought was) some good AMC information.

That site was upgraded with the new site, so most of the information is gone. Therefore you'll have to ask to get the information you need, but I'm sure that they'll know whatever you want.

http://www.froadin.com/

Or, you could try an AMC car site. There are a lot of guys with old AMX and Javelins that I'm sure would be happy to help.

http://p214.ezboard.com/bamcforum - old link
http://amcforum.net/ - new link

Thanks for the links guys! Yeah, the weird part about all of this is that when flat ground until I hit 2000 plus RPM it is perfectly fine. It starts fine, idles fine, sounds fine then I hit it and get the clattering. I don't think it is losing power either. But I can't be sure. I have only been running this motor about 8 runs really hard. I told my buddies that every motor that I have seen that has had a kncok or lifter problem, that it never goes away. It may be louder at times or speed up with the RPM of the motor, but it never goes away. This definitely comes and goes. I was thinking of changing the oil and filter too and put a really good oil in it. Does anybody have any input about synthetic motor oil. I just recently put this motor together and it doesn't leak a drip. (Which is sayiong aomething about an AMC!) I have heard that using synthetic could cause leaks. Also, do es anybody think maybe for some reason I am just not getting oil to the top end of the motor and maybe Synthetic could help out with this?

One other thing I thought of. When I was running this thing over the weekend, a couple of times when I went to start the motor, it struggled to crank over. I have a brand new Optima battery in it, so I know that it wasn't a battery problem. I was told my timing was advanced a bit too much. Could that be part of my problem too?

if yoru timing is too advanced it will make that gurgling death rattle sound, its also hell on your engine.

retard the timing, and or use higher octane fuel.

I think the oil pressure on an incline is an unrelated issue.

I hate to say it but I think your rod bearings are wiped.

It will run fine, and soud fine until you get some rpms and/or load on the motor and then it will start clattering- that's bad.

I would drop the pan and take a look before doing anything else. 401 cranks are hard to find so don't damage it any more!

Worse case you are looking at a short block overhaul.

I would definatly check your bearings just to be safe, it isnt a ton of work and like mentioned it would suck to kill a 401. Get some plasti gauge at least and see how tight things are. If the bearings are fine I would at least put in a new oil pump and double check your valve train, decking the heads and a new cam I wouldnt be suprised if there is a pushrod problem. Finally ignition could obviously be an issue, running 10:1 on an iron headed engine you need to be very careful on the timing and I hope your running at least 91 octane gas.

It sounds to me like you have taken out your rod bearings. 401's have a very poor oiling system and you should really have a miladon (sp) 7 qt pan on them. I have killed mine 8 times with 5 of them due to oil (or lack there of) issues until I put the big pan on. They have pump all the oil up to the heads and it takes forever to drain back to the pan. Another favorite thing for a 401 to do is to suck the oil that is trying to get back to the pan up the pvc valve. This makes a really impressive cloud of smoke near the top of the hill! Look at the oiling tips on froadin.com if you have to do a short block it will be worth your time.

Good luck!

$50 some trash or gasket debris got into the oil pick up screen and is blocking oil flow into the pump. that would explain why it was fine before the head swap took place. Something may have fallen in the motor while cleaning the sealing surfaces.

My old 401 was heavily abused and saw regular spins to 6500 rpm. The only oil mod I did was the Milodon pan- nothing else.

Except for the forged 9.5 pistons and cam, the short block was stock.

Hey guys thanks for the input. I am going to pull the pan and see what I can see. I will also check the pushrods and timing as well. I do not know how to check the bearings though. I have been reading some about plastigauge. Anybody care to give the quick lowdown on how to check them? I figure I will start tearing down and check all of these things. If the bearings are bad then I have to tear it all down anyways! Yes I am running 94 octane all the time in it. Sounds like I need to get the Milodon deep pan too. I will definitely do that. Also, do you guys recommend roller rockers? Would those really help me out? I know they are supposed to really relieve a lot of friction which allows more RPM. I am geared really low, but with all the mud here in Ohio and Kentucky I really need to be able to spin tire sometimes. Thanks again, Jesse. :)

Jesse Ive seen these things cause those types of problems

1. loose converter bolts
2. bad clutch
3. broken piston skirt
4. loose rocker
5. collapsed lifter
6. wrist pin
7. a bolt loose in the lifter galley
8. fuel pump

Do you experience a power loss?

No, I don't notice a power loss. I am going to replace the oil pan with a milodon pan, but I don't really know what to look for when inspecting the bearings. Also, what will be the best way to turn the motor around to get a look at them. Maybe pull the coil wire and crank it around with the starter? I think I really want to just redo the shortblock because I think I have a little blow by on my rings from increasing the compression and not re-ringing it. Does anybody have a suggestion on pistons to use. Also, does anybody know how much compression I can run without getting crazy with the fuel? I am willing to run a mixture maybe, but I don't want to have to go to Turbo Blue or something. This thing never sees the street and I only wheel about 15-20 times a year.

first you will need to establish your bore for pistons. Some piston makers dont go over 40. I would look at your cam bearings if you rebuild the shortblock. You can drill a .201 (nominal #7) hole about 180 degrees from the original .250 hole in the cam bearings to allow more pressure to the last bearings. This also forces more oil into the lifter bores. Sometimes we install pills in the pushrods, these allow less oil to flow out the pushrod and this also increases the flow to the mains, here is how the oil flows in your AMC V8..notice the lack of priority in the oiling system?

http://bulltear.imgbay.com/Oilflow.jpg

Sealed power make some great pistons for these and that may have been your problem. The cast pistons and the long stroke really makes for cracks and failure due to the thin areas around the wrist pin and skirts.

http://bulltear.imgbay.com/401piston.JPG

Companies like Edelbrock and Indy cylinder make some awesome aluminum heads which disapate heat well so you can run 10-1 compression and a mid grade octane and even a lower octane depending on elevation.

http://jeepsr4ever.imgbay.com/Edel3.jpg

You can add a oil line instead. The lifter valley is where this goes. Sold at performanceamstyle.com

http://www.imgbay.com/sites/jeepsr4ever///oilmod4.jpg

We also make oiling system upgrades


http://jeepsr4ever.imgbay.com/NEW%20078.jpg
http://jeepsr4ever.imgbay.com/Midpl.jpg
http://img.photobucket.com/albums/v442/pyagid/Midplate.jpg


We even coat timing covers for extreme wear, only available to racers untill last year
http://www.imgbay.com/sites/jeepsr4ever///bulltear20006.jpg

I went with forged pistons and roller rockers. Because the roller rockers need less oil that std rockers (less friction) you can drill a new smaller hole (half the size) in the cam bearings 180 degrees from the current hole install the bearings with the small hole where the large hole would normally go and than the motor will not pump as much oil up to the top end and keep the oil in the rod & main bearings.

Just a cheap trick from AZ.

I would pull the main caps (#2 & 4 seem to get hammered first) to see how they look and than usually #8 rod (farthest from the pump or last to get oiled). If they are squished out (hammered) or all copper colored than they are done. A little bit of copper is normal and maybe some small grooves.

MC can you coat the inside of the oil pump where the gears are? After blowing up a few motors all the crap goes through the gears and ruins the sides. I have a couple of covers laying around and need a good one for my spare motor (that is another way to keep a 401 going is to keep a backup around to threaten it!).

We used to do used covers and refurbish them but with the quality covers that are NOW coming from crown it isnt suggested that you refurbish a new cover since we take a new one and nickel coat it for less than you can refurbish a old one. We have had 3 sets of distributor gears go through a nickel cover with just taking the smallest amount of nickel off the pump cavity. It is the end all to the wearing problem. we have tried

tig welding remachining
titanium coatings
copper coatings
boron coatings
chrome and hard chrome coatings
anodized coatings
stainless steel inserts
oilite bronze inserts
machining a whole new cover from 303 stainless steel (nightmare)

The nickel is the best possible treatment we have found. The nickel coats the inside of the pump evenly as well as the outside, thats the shiny cover in the illustration. Extremely abrasion resistant...extremely blingy :D

Yes we all need more blig! :laughing: What is a ballpark figure on the new blingy cover?

They are $350 and this includes new gears installed new spring, plunger a .0085 gasket. We did list how to do it yourself on our site but it would cost over $500 to do just one

Great, Thx MC!

I guess I am through hi-jacking this thread. Again Good Luck GodzillaJeeper!

try this thread. AMC401 pulls it up hope it helps.

http://www.pirate4x4.com/forum/showthread.php?t=245386&highlight=amc401

And you all need to go visit MC's stuff over at Bulltear.com highly recomended. great quality and great service. Lots of bling bling AMC goodies

MAN, THANKS FOR ALL THE INFO! I had no idea that there was this much stuff out there. I have been checking out Bulltear.com too. I have found a lot of great info on there. I think I am going to do the cam bearing mod and the oil line mod too. With all of the off camber wheeling I do, it sounds like good piece of mind. I don't think I follow this nickel coated deal though. Are you saying that the entire pump and timing cover assembly is coated with nickel to hold up better to wear?

The whole pump is coated for wear and abrasion the nickel is many many many times harder than the aluminum casting so you have a rock hard surface, the whole problem is that the oil gets to the pump before the filter. The advantage is in the pump cavity, the outside is coated because it is impossible to maske the whole cover...but it looks nice

In Los Angeles county I know an AWSOME AMC engine builder.
Thats pretty much all he does / specializes in. Anyone interested
in getting an engine or an engine built PM me your phone number.

Unfortunately
it will not be possible to "spill the beans" online. 304 360 401, whats
your flavor and how much money do you want to spend starts the ball
rolling.