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Thread: oil pressure drops at topend of the track

  1. #1
    Senior Member DYNO OPERATOR Swiley383's Avatar
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    oil pressure drops at topend of the track

    I ran my car for the first time this year on Friday. I saw the oil pressure was down to about 15 to 20 psi as I crossed the finish line at a little over 6,000 rpm (I shift at 6500}Idle oil pressure is fine as well as driving around the pits. I changed the oil before racing since the car has set all winter with 20W50 VR1 and a wix oil filter. I also noticed when I let off pass the finish line it took a second to return to normal pressure. Do I need to worry about this or could it be a gauge problem? The motor is a 12.6 to 1 383 sbc with Eagle 4340 rotating assembly Dart pro 1 heads and a solid flat tapped cam with a high volume oil pump (not a melling I think its a speed pro). The motor has been together for about 7 years but has not been ran very much. The motor has a 7qt pan with trap doors in and I am running the 1/8 mi. any ideas?

  2. #2
    Senior Member RACING JUNKIE
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    Just a SWAG here, but I'd guess that you're running out of oil. It's all in the assemly, with little left in the sump.

    It might also be that the "Trap Doors" aren't working . . Which, again. would account for the "Running out of Oil" deal. It isn't letting the oil come back, and it isn't keeping it there once it gets there . .

    Note the word "GUESS" . . .

  3. #3
    Senior Member RACING JUNKIE TheYellaBrick's Avatar
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    This bullet have a windage tray ? If not, you're probably getting a lot of rope action going on where the oil isn't getting back down to the pickup.
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  4. #4
    Senior Member DYNO OPERATOR Swiley383's Avatar
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    no it dose not have a windage tray. Should I pull the pan or is the pressure droping enough to cause any damage?

  5. #5
    Senior Member RACING JUNKIE
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    Agree with Roadkill

    Probably pumping all the oil to the top side. I bet you don't have restrictors.
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  6. #6
    Senior Member DYNO OPERATOR Swiley383's Avatar
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    no, there are no restrictors in the motor. Should that be somthing I should look into adding?

  7. #7
    Senior Member RACING JUNKIE curtisreed's Avatar
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    My two cents here. I am really surprised you are having trouble only running the 1/8. I would add a 1/2 quart first and see if that makes any difference. I could be that you are pumping the oil up top and it can't drain back fast enough.

    I mean you no offense but for the life of me I can't understand why people run high volume oil pumps in a SBC. I can't imagine the clearances you would have to have to run out of volume with a std. pump.

    Were you having this problem before you changed oitl? If not then I would look at your filter. That is probably not the problem but if it just started, then that and the oil is all that changed.

    If you run a vacuum pump or you have much blow-by that is all trying to come to the top where the relief is, and the oil that is up top is trying to get back down. It gets worse if you run vents in the drain holes over the cam, screens over the drain holes at the ends, etc..... Big fight for space between the two. Improving drain back from the heads is a big plus. Just my observations. Many others are better versed than I.

    Curtis

  8. #8
    Senior Member RACING JUNKIE
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    This is a pretty common problem, usually a oil pan issue and oil running away from the pickup. Sometimes more oil will fix it but not often.
    David Lanning
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  9. #9
    Senior Member DYNO OPERATOR Swiley383's Avatar
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    never noticed before I have never looked at the gauge going down the track until this time out only then because I had to lift as I got the car straighned out I just happend to look at the gauge. As for the droping after the finish line seems like it has always droped slightly but I don't remember it being this much of a drop. I always check my gauge after the finish line I really don't wont to take a chance hurting this motor. I have heard differnt ideas on safe oil pressure levels what is your thoughs on oil pressure levels?

  10. #10
    Senior Member DYNO OPERATOR Swiley383's Avatar
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    I also don't know how it could be running out of oil in the 1/8. The big block I ran for a long time had a stock pan and a HV pump with no problems. I was only shifting that motor a 5500. When I first built the 383 there was a problem with the oil pump I had. When the motor reached about 180 degrees the the pressure would fall to nearly 0. I tore it back down an replaced the the pump and bearings just to be safe. That is when I learned of the problems with Melling pumps and did not use a melling the second time around and never had anther problem. I do not remember why I put a high volume pump in this one I learned more since then and know they are really not needed.


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