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  1. #11


    There's a thread regarding the internal oil line modification here that some of you may find of interest. I posted my reply there but because of the similarities of the topics in these threads I thought it may be helpful to get another perspective. So I asked Larry Mitchell, the former National Director of AMC World Clubs (retired) and owner of AMX Enterprises for his opinion. He has built numerous AMC engines, raced his '69 AMX in many events over decades including the Silver State Challenge and the Pikes Peak Hill Climb. He replied with the following:

    An ideal AMC V-8 should hold 20-25 pounds of pressure at hot idle and 60-65 pounds above 3,500 rpms. Please note that when these engines were new in the 1960s/1970s THEY DID! This is on 10W30 oil.

    Rumors have abound for years about "oiling problems" inherent in an AMC V-8. IT ISN"T TRUE. AMC offered a 5 year, 50,000 mile warranty from 1968 and up and this is a period of time when owners of these cars were bashing them at stoplight drags on every street in America everyday and night of the week. And on weekends, they bashed their AMXs, Javelins, Machines, Scramblers et al at the dragstrips just like everyone else was doing with their Camaros, Cudas, Mach 1s, Challengers, GTOs and the like. AMC engines had no more or less problems with oiling than any of these other brand cars at the time. The only time oiling became a serious problem with ANY of the musclecars of 35 years ago was in SUSTAINED HIGH RPM DRIVING. Like over 100 miles an hour for 2 or more miles at a time. Then, any Ford, Chevy, Mopar or AMC engine would pump the pan dry and before the oil could get back into the pan, the rod bearings starved for oil and the engine seized and broke rods and stuff. Cornering back then on Polyglas belted tires and only a front sway bar caused no problems with loss of oil pressure because the average musclecar back then could not generate enough "Gs" to starve the oil pickup. With modern high performance tires of today and an aftermarket sway bar pack, you CAN easily starve the oil pickup on any of the old musclecars and trash the motor in seconds.

    Overall, keep in mind all the Los Angeles AMC Police Matadors and the Alabama Highway Patrol 1972 Police Javelins had no special mods to the 401 motors with the exception of a slightly modified "police" oil pan. If all AMC V-8s suffered SERIOUS OILING PROBLEMS back then, don't you think they would have FIXED THE PROBLEMS to stop major financial losses on warranty claims AND don't you think the word on the streets and in car magazines back then would have killed sales of AMXs, Javelins and the like because engines would have failed right and left AND EVERYBODY WOULD HAVE KNOWN IT!?

    A. If you are not going to drive your AMX or Javelin hard, you only need to make sure the following is done with an engine rebuild: The rod and main bearings MUST be clearanced as close to .001-inch as possible but not less than that figure. The rear main should be .0015. This is what all AMC shop manuals state the clearances are. If bearings are clearanced to "Chevrolet 350 specs" as most shops want to do, the oil pressure in your AMC V-8 will drop like a rock. Chevy engines oil the rods and mains FIRST and in order to pass lots of oil on to the rest of the engine, bearings are clearanced to .0035 to .0045-inch. AMC engines oil the rods and mains LAST and so bearing clearances must be tighter to properly lube and keep general engine oil pressure UP. Also in rebuilding your AMC engine, replace the timing cover with a brand new one, replace the oil pump gears with a new set, do not over tighten the oil pump cover-use stock torque specs and replace the oil pickup tube in the oil pan. This is all you need to do on a stock-to-strong street motor.
    (note: the oil pickup tube can easily be cracked if overtightened and will suck air causing the oil pressure to drop. This can be very difficult to detect if you're not aware of it. ed)

    B. If you put on modern high performance tires and especially an aftermarket sway bar package AND you "get on the car" some, run one quart over stock in the oil pan at all times.

    C. If you are going to set up your AMX or Javelin today with serious modern high performance tires and a sway bar package and run the car damn hard a good part of the time, you will HAVE to have a "Trans-AM" style 8.5 quart "racing" oil pan with external pickup lines and oil pump bypass adapter.

    D. If you are going to seriously race your AMC car in autcrossing or high-speed road or track events WITH SUSTAINED HIGH RPM DRIVING (above 4,000 rpm for more than 3 minutes), you will need the internal oil line from the front of the oil galley to the rear between #7 and #8 lifters. If you are NOT running SUSTAINED, HIGH RPM DRIVING/RACING, you DO NOT NEED THIS LINE! It is overkill and will drop your total engine oil pressure 5 or more pounds across the board.

    Are you only getting 10-25 pounds above 3,000 rpms? If so, you have a serious DEFECT in your engine. Or, a faulty gauge. You can only really trust a mechanical gauge properly hooked up where the previous factory electrical pressure sending unit was. And, the gauge must have the line from the motor properly bled to get an accurate reading.

    The biggest cause of low oil pressure is an IMPROPER REBUILD by a shop full of Chevy lovers!


  2. #12

    Default engine loses oil pressure when it hits 200 degrees

    Who about the Pan to Pickup clearance? I rebuilt a 360 that had good pressure when pump was driven with drill, would loose pressure when engine started, Found out the pickup was too close to pan.

  3. #13


    Holy cow am I glad I visited this evening. I stripped my 360 down to a long block state and will be dropping it off for rebuild at Nevada Valve Train tomorrow. I plan on having a talk with them about proper clearances and I copied all the specs from my service manual for them to go by.

    My Specs indicate

    Main Bearing Clearance .001 - .003 (.0025 prefered)

    Rear main .001 - .003 (.003 prefered)

    Connecting Rod Bearing .001 - .003 (.0025 prefered)

    74 Javelin

  4. #14

    Thumbs up Following Specs

    I recently did my 401 (well okay, last spring) and I managed to find a Machine Shop that would follow the specs as outlined in the Tech Manual as put out my AMC. I ran as tight as the specs allowed and have suffered absoultly no problem at all.
    The specs follows what the factory had done. There is one very important issue here and that the bearings (both rod and mains) must be tight or the result will be devasting to the engine. For example: a 360 that was done by a shop used the GM specs of .0025 for the rods and mains. This engine gernaded in 2500 miles. I am talking from experience because I did it and I destroyed it on a chasis dyno. It was after the dyno that I realized that the shop did not follow the tech manual for AMCs but rather that of some GM book.
    I strongly urge anyone who owns a AMC to buy the tech manual for any particular year. The manuals are invaluable and a real good source of information for they were written by the people who put out the cars. It would the best money spent for any AMC enthusists.

  5. #15
    Join Date
    Feb 2006


    got to agree with Big Bad AMX and Donsjave on this one,had a 68 with a 343 back in 1986 that had a good tight motor and oil pressure was never an issue,even when the smoking rear tires and the Sherriff's Dept, that was another to another one i assembled using a "rebuild kit" from the local auto parts store, it only saw 50 p.s.i. when COLD was 20 p.s.i. at highway speed when warm and about 5 p.s.i. at i ran valvoline 20-50w racing oil in that motor along with STP oil treatment.probably was close to 90w gear oil with that blend.motor lasted about 40k before becoming a smoker.and of course i did NOT check bearing clearances on that "rebuild" kit,using "standard" size rods and mains.and yes we were reading about oil filters and oil pressure relief/bypass modifications that never seemed to answer as to WHY oil pressure was low 21 years ago.Larry Mitchell's experience kinda gives you the notion that he has been down this road long before he decided to run in any of the events he has done so i'll put the house payment on his advice---just my opinion

  6. #16


    The specs I posted above came directly from the AMC Technical service manual for the 74 model year vehicles. I spoke at length with the rebuilder and was satisfied he knew the specs I wanted. I'll know in a few weeks if things are good when I get everything buttoned up and back in the car.

    74 Javelin

  7. #17

    Default Sorry about that

    Quote Originally Posted by Javelin360
    The specs I posted above came directly from the AMC Technical service manual for the 74 model year vehicles. I spoke at length with the rebuilder and was satisfied he knew the specs I wanted. I'll know in a few weeks if things are good when I get everything buttoned up and back in the car.
    I am not doubting you at all as to where the specs came from, just that the tighter the clearances are, the better off you are.

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