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Debating oil mods for a 401

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Airdrie AMX View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Airdrie AMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 2:19pm
5500-6000rpm sounds like a relatively mild performance build, personally I would fit a larger capacity pan and forget about the rest. As an example my current 401 is similar, 6200rpm max hydraulic cam etc... and it gets driven hard every time I drive it the only thing in the way of oil "mods" are a milodon 7qt pan and swinging pick up. I have never experienced oil pressure issues as in pumping the pan dry and momentarily loosing pressure. So far in the 8 yrs I've been abusing it LOL it seems pretty bulletproof. At your intended rpm goal I wouldn't get caught up in crank oiling "problems" if that were the case 401 everywhere would be self destructing. Just my opinion.
72 amx javelin 401 4spd
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gremlinsteve Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 2:25pm
I agree. I've decided to keep it simple
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 4:21pm
In my experience the biggest problem with high output AMC V8s
is all that oil staying in the valve covers and rear of the
lifter gallery.

A high capacity pan can mitigate this very real problem.

AMC like Buick (Nearly identical oil system in most respects) did a lousy
job on returning the oil to the pan.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote gremlinsteve Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 5:17pm
Jcisworthy and I where just talking about that
I think I'll be putting a canton oil pan onto this motor also
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JERSEYJOE Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 5:39pm
I have to put in a few words here. If you check out my project AMX you will find that I have a lot oiling mods NOW. When the AMC factory guys put it together in 1970 to race SCCA B production they had very few oil mods. The car raced up until 1975 with NO engine failure. The only mods were:

Oil drain back from the valve covers to the pan. Basic stuff, keep the oil in the pan and not upstairs.

2 quart Accusump in case there was a cavitation the Accusump supplied the system with oil for a couple of seconds.

Blueprinted oil pump and external feed from pan.

Oil cooler.

There was no valley oil line ever, don't think that in 1970 anyone discovered this yet. NO camshaft anti-walk set up or distributor gear oil mod.

Of course it has all this stuff because I felt compelled to do so!!

After I bought the car in 1981 and thrashed it on the street for a couple of years I took the motor apart and there were zero issues.
When I redid the motor for the current project of course I replaced the bearings after the crank was inspected and only polished. The valley line does work but for your needs I would say not needed. Spend the time and money and put at least one oil drain back from the valve covers to the pan and maybe a cooler and call it a day
1985 CJ 7 401 dana 60's 37's
1987 J-20 401 Stock resto
1977 CJ 7 360 T-18 D 300
1970 AMX ex-SCCA car


SPEED COSTS MONEY HOW FAST DO YOU WANT TO GO?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gremlinsteve Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 6:02pm
Awesome input
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wantajav Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 6:47pm
For me (343 build), I'm planning on adding 1 extra quart of oil, that seems to mitigate a lot of the issues...

step two: making sure the oil pump is factory tight for clearances and the timing cover is straight...

step three -making sure the block factory passages are clear. No flashing or restrictions.

...and using both high zinc oil  (Joe Gibbs or similar) AND zinc additive at all times. That's what my machine shop guy recommended, the oil and the additive both.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote BillyBobsAMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 7:53pm
I recently read on youtube that the 401 is a truck engine and will eventually blow apart due to bad oiling. So I advise you not to run an AMC motor.WinkWinkWink

Edited by BillyBobsAMX - Oct/07/2017 at 8:00pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JERSEYJOE Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 8:06pm
Well I can tell you there are a lot of 401's running around that put out a lot of HP without exploding, but I may agree the rod ratio is not as forgiving as a 390. Still with proper assembly they are very reliable.
1985 CJ 7 401 dana 60's 37's
1987 J-20 401 Stock resto
1977 CJ 7 360 T-18 D 300
1970 AMX ex-SCCA car


SPEED COSTS MONEY HOW FAST DO YOU WANT TO GO?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Oct/08/2017 at 6:01am
Originally posted by JERSEYJOE JERSEYJOE wrote:

Well I can tell you there are a lot of 401's running around that put out a lot of HP without exploding, but I may agree the rod ratio is not as forgiving as a 390. Still with proper assembly they are very reliable.


From what I gather, above 5000 RPM the 5&6 rods will run drier than the rest and spin a bearing. This is due to an improperly drilled crank. No other AMC crank is done that way. That is why I stuck with a 390 in selecting a build. Actually I am reversing the lifter valley mod, as it is not required. I truly think due to the 401 being raced brought up such a mod, and peeps were using it on all builds thinking their non 401 needed it.

Though there are a few who have had the 7 and 8 rod bearing issues with stock 2nd gens, are mostly with the 401.

To be honest a factory oiling system with a stock oil fill does well at no higher than 5000 RPM with a 304. Believe me I abused my mostly stock 304 like a mad man back in the day. I can't say that a 401 could handle a lot of 5000 to 6000 RPM with out correcting some of the inherent issues with the incorrectly drilled crank.

Edited by 304-dude - Oct/08/2017 at 6:33am
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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