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Old August 21st, 2014, 12:49 PM   #1
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Default AMC - high oil pressure?? *VIDS*

Hello,

I recently have a problem with high oil pressure which is interesting because AMC's are known for really poor oil pressure

Motor: AMC 401, modded... but nothing too crazy

Oil pressure on cold start up is 60, but within 1-2 minutes of idling at 550rpm, pressure climbs to 75. I have not let it warm up to see if the pressure will drop, I fear with a pressure of 75 I might cause damage.

My oil pressure used to act normal (60 cold, 35-40 warm), but recently I developed a tick which ended up being a set of loose rockers. I fixed the loose rockers with the motor running, tightened them until the tick stopped, and then another 1/2 turn -- SUCCESS, no more tick, runs beautifully. However, now I have an oil pressure issue.

Last time I did an oil change (about 15 start-ups ago, 0 miles ago ) I checked my oil pressure relief spring, etc... all appeared well. Plus, after that I have fine oil pressure anyways.

questions
1: Is high oil pressure harmful to the motor?
2: Can over tightening, or messing with the rockers in any form cause high oil pressure? I checked my lifters by pushing down on the rod end of the rockers while I was in there, and non of them were squishy - if that matters. The motor is running strong, doesn't die off when pushing the gas or putting it into drive/etc... I would think if I over tightened them, it would be struggling to run and stall with exertion.


Please halp, I don't want to hurt my motor that I love dearly

Last edited by Leanz; August 27th, 2014 at 12:40 PM.
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Old August 21st, 2014, 01:29 PM   #2
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My 360 is always around 60-75 psi. It never gets up over that, and it does drop a bit if I'm running it hard. I never thought anything of it.
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Old August 21st, 2014, 01:33 PM   #3
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I have seen oil filters blow up from excessive pressure. Yours don't qualify. Overtightening the rockers would make it run poor and hurt the pistons.
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Old August 21st, 2014, 02:15 PM   #4
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Quote:
Originally Posted by Leanz View Post
Hello,

I recently have a problem with high oil pressure which is interesting because AMC's are known for really poor oil pressure

Motor: AMC 401, modded... but nothing too crazy

Oil pressure on cold start up is 60, but within 1-2 minutes of idling at 550rpm, pressure climbs to 75. I have not let it warm up to see if the pressure will drop, I fear with a pressure of 75 I might cause damage.

My oil pressure used to act normal (60 cold, 35-40 warm), but recently I developed a tick which ended up being a set of loose rockers. I fixed the loose rockers with the motor running, tightened them until the tick stopped, and then another 1/2 turn -- SUCCESS, no more tick, runs beautifully. However, now I have an oil pressure issue.

Last time I did an oil change (about 15 start-ups ago, 0 miles ago ) I checked my oil pressure relief spring, etc... all appeared well. Plus, after that I have fine oil pressure anyways.

questions
1: Is high oil pressure harmful to the motor?
2: Can over tightening, or messing with the rockers in any form cause high oil pressure? I checked my lifters by pushing down on the rod end of the rockers while I was in there, and non of them were squishy - if that matters. The motor is running strong, doesn't die off when pushing the gas or putting it into drive/etc... I would think if I over tightened them, it would be struggling to run and stall with exertion.


Please halp, I don't want to hurt my motor that I love dearly
What oil filter do you have on it? What weight oil? What's the lash on the rockers?
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Old August 21st, 2014, 03:07 PM   #5
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Are you certain that your oil pressure gauge is giving a proper reading? I would also reset the valve lash properly rather than trust the way you did it since the cost of an amc build can get pricey.
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Old August 21st, 2014, 03:48 PM   #6
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Loose rocker arm will cause lower oil pressure so by tightening them you could increase pressure a little. I don't see a problem with how you adjusted them i've done that on chevys many times, my amc still has the bridges so not adjustments. My concern with too much pressure is the cam and distributer drive gear wereing to fast, i suggest a bronze gear. I don't know a too high number i have heard 10 psi per 1000 RPM would keep a motor alive. My 360 idle cold at 65 revs cold to 75 idle hot about 30. 15-40 summer 10-30 winter. Sounds like your is ready to head for Hale I am heading over in the morning.
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Old August 21st, 2014, 05:29 PM   #7
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Im guessing you have roller rocker arms because I dont believe the 401 ever came with adjustable rockers. Oil filters have a by pass valve in them which is usually set around 60-70 lbs. Any time you have more pressure your oil is not being filtered. This is fine for a few minutes at cold start or while using lots of rpms for a bit, but not good if its all the time.

If you have a electonic op gauge I would hook up a mechanical guage to see what you actually have. Electric gauges are not always accurate and can develope problems like leaking sending units, or a short.
A piece of dirt can plug a sending unit and cause it to read high. A leak will read low, and a short or faulty sender or gauge can go either way.

A spun bearing, cam going flat, or ANY restriction in the oil gallery can cause high pressure.
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Old August 21st, 2014, 10:26 PM   #8
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Thanks for all of the input!

These are the bolts I was adjusting -->
Am I wrong by calling those rocker bolts?
My rockers are still bridged, and are not roller rockers.
It is a mechanical oil pressure gauge, and I trust its giving a true reading - it is very responsive to any slight blip in RPM's.

If it matters I have rhodes variable duration lifters in it...they all seemed fine.

How will over tightening rockers hurt my pistons? I am a visual learner and want to picture in my mind how that might hurt the pistons. From my understanding rockers directly effect lifters,cams,rods,valves and not pistons? But I could be understanding it wrong, unless you mean the valve smacking the top of the piston if I have it tightened so much the valve is stuck open, in which case it wouldn't really run much lol

So a while ago, I had 2 broken rocker bridges. I replaced the two broken ones and I was reading my manual and it said to torque down the rocker pivot nuts to 19ftlb's, so I did this. 5-8 motor starts later, one of the sets became loose and started to tick... that's the only set that I adjusted by running the motor, tightening until the chatter went away then another 1/2 turn. All of my other rockers were quiet and tight, so I didn't check their adjustment.

When you say adjust valve lash, do you mean adjusting the rocker bolts according to the rod tightness/spin-ability ?

How much oil pressure do you have to have to blow off an oil filter??? Am I close?

Last edited by Leanz; August 21st, 2014 at 10:33 PM.
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Old August 21st, 2014, 10:32 PM   #9
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Those should all be tight,
the only way i could see tightening the rocker arms down tight causing higher oil pressure would be if you somehow managed to block off the oil holes in the rods causing a blockage.

Your motor has non-adjustable rocker arms, and are studless. pretty much tighten them down to spec and they should be good to go, shouldn't harm anything.
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Old August 21st, 2014, 11:50 PM   #10
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so sandals, should I lead my investigation towards my oil pressure relief valve? Perhaps the plunger is stuck? I just don't want to waste all of the oil I just put in there
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Old August 22nd, 2014, 08:25 AM   #11
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Quote:
Originally Posted by Leanz View Post
so sandals, should I lead my investigation towards my oil pressure relief valve? Perhaps the plunger is stuck? I just don't want to waste all of the oil I just put in there
A lot cheaper then fixing a motor... Part of the game...



Here read this... This well help start your understanding about valve lash and valve train...

http://www.dragzine.com/news/how-to-...sh-like-a-pro/


Also change out the filter... See what oil pressure does then...
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Old August 22nd, 2014, 03:19 PM   #12
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Mechanical or Electrical guage? When my electrical sender started to fail I got all sorts of strange readings.
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Old August 22nd, 2014, 04:55 PM   #13
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Relief valve in oil pump could be sticky?
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Old August 22nd, 2014, 11:14 PM   #14
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Quote:
Originally Posted by Leanz View Post
It is a mechanical oil pressure gauge, and I trust its giving a true reading - it is very responsive to any slight blip in RPM's.
.
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Mechanical or Electrical guage? When my electrical sender started to fail I got all sorts of strange readings.
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Old August 24th, 2014, 02:14 AM   #15
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hahaha Thanks Beaner, I have a feeling a few people aren't reading my comments completely Oh well, I appreciate everyone's input!

Still one question unanswered.... How high does my pressure have to be to blow off my oil filter? Should I let it sit at 75psi for a few mins and see if it comes down or continues to climb? Or just not run it again, and check my oil relief valve.....
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Old August 25th, 2014, 06:42 PM   #16
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how much oil was blowing out of the pushrods when you had it running with the vave covers off?

What oil are you running? - You could switch to 5-w30 or 0-w30 synthetic.

Did you do the oil mod in the lifter valley?
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Old August 25th, 2014, 07:09 PM   #17
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I have seen 100 psi without blower off a filter on other motor. That should answer that question. I reved my 360 cold this weekend and seen 80 PSI I think yours is fine. At this point start it and let it warm up. The very worse case is you will loose some oil and a filter but from what you have described I think you are OK. That style rocker are torqued down and are good to go. Yours are made of aluminum and they do were quicker then steel ones. But as long as the bolts are tight and you have no ticks run it.
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Old August 25th, 2014, 07:47 PM   #18
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Quote:
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how much oil was blowing out of the pushrods when you had it running with the vave covers off?

What oil are you running? - You could switch to 5-w30 or 0-w30 synthetic.

Did you do the oil mod in the lifter valley?
Yes, I did the oil mods in the lifter valley and I believe I am running 5w30 synthetic already - I'll have to check my oil container to be sure what weight I put in.

A good amount of oil was coming out of the rods/rockers when I was running it with the valve covers off. I put up a cardboard shield, but with all of the commotion I think the cardboard shield slipped off of my head a little bit and my drivers side manifold got a good oiling not enough oil to roll down the manifolds and drip on the floor, but definitely enough to smoke for a bit... I actually have a short video of my motor running with the valve cover off, before I fixed my tick.... maybe I'll post that
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Old August 25th, 2014, 07:59 PM   #19
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A topless post from leanz? Meow!
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Old August 25th, 2014, 08:06 PM   #20
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Here I am with my cover off
http://vidmg.photobucket.com/albums/...818_114250.mp4

I guess tomorrow I'll let it warm up, granted the oil pressure doesnt climb even higher, and see if goes back down. Last time I ran it, it appeared that it was just going to keep climbing....so I got nervous and shut it off. Tomorrow I will find some balls, and see what happens

Last edited by Leanz; August 25th, 2014 at 08:12 PM.
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