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Debating oil mods for a 401 |
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Airdrie AMX
AMC Nut Joined: Aug/08/2010 Location: Alberta, Canada Status: Offline Points: 329 |
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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.
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72 amx javelin 401 4spd
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gremlinsteve
AMC Addicted Joined: Dec/16/2008 Location: houston Status: Offline Points: 884 |
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I agree. I've decided to keep it simple
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4210 |
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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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Gremlin Dreams
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gremlinsteve
AMC Addicted Joined: Dec/16/2008 Location: houston Status: Offline Points: 884 |
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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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JERSEYJOE
AMC Addicted Joined: Oct/23/2008 Location: TUG HILL NY Status: Offline Points: 1718 |
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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 |
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1985 J-20 PLOW TRUCK
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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gremlinsteve
AMC Addicted Joined: Dec/16/2008 Location: houston Status: Offline Points: 884 |
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Awesome input
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wantajav
AMC Addicted Joined: Sep/04/2009 Location: PA Status: Offline Points: 1151 |
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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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BillyBobsAMX
AMC Fan Joined: Oct/07/2017 Location: Sweden Status: Offline Points: 2 |
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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.
Edited by BillyBobsAMX - Oct/07/2017 at 8:00pm |
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JERSEYJOE
AMC Addicted Joined: Oct/23/2008 Location: TUG HILL NY Status: Offline Points: 1718 |
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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.
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1985 J-20 PLOW TRUCK
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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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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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 |
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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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