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| Andrew | Oil Pressure Fix - Need input | ||
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I'm still having problems with oil pressure dropping at ~4k rpm's. Strong pressure at idle and driving, but at WOT and 4k rpm's, it starts to drop (from 60 at 3500 down to 30 at 5k). So, here is my plan of attack and I need advice. Am I headed in the right direction?
1. Get a manual pressure gage and watch it while driving. One question, on other SBC's I've owned, there was a port near the front of the block where I can plug a sensor into with a gage. Is there a port like this on the LT4, so I can see the stock gage and the manual at the same time? This will eliminate the possibility of a bad sensor or gage. 2. Pull the filter and make sure the bypass is clean. 3. Change to another filter. 4. Last resort, check the oil pickup and change the oil pump. Can this be done without pulling the motor? I have access to a lift, so I hope there is enough space to pull the pan to do this. Again, last resort. What am I missing in tracking down the culprit? |
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Posted on: 2012/1/15 19:24
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2003 Atomic Orange Z06 Sold - 1996 Competition Yellow LT4 - DRM 383, NX N2O, Line Lock, LT Headers, 3" stainless exhaust, Power Effects, and many more mods SOLD 1996 Competition Yellow LT4 SOLD 1979 4 Speed with 383 |
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| rklessdriver | Re: Oil Pressure Fix - Need input | ||
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Senior Guru
 
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Yes there is the oil pressure port in the back of the block but the stock oil pressure sensor and sendor are screwed into a T there.
Will |
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Posted on: 2012/1/15 19:42
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1984 Corvette. 434 SBC with a Powerglide. Best pass - 8.48@160MPH 1.23 60ft on MT 275/60R15 Radials. 1972 Corvette. LS5 454 BBC with M20 4 speed. Best Pass - Doing good to just pass a gas station. |
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| bogus | Re: Oil Pressure Fix - Need input | ||
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Grand Imperial Pooh-Bah
 
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Did the pickup get tack welded to the pump?
Is it a high volume pump? Could you be sucking the sump dry? Have you considered an Accusump? What about a high volume oil pan (Canton)? And yes, you can get at the stock oil pan without a lift. Worst case, you need to manually turn the crank 1/2 turn to clear the front counterweight. |
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Posted on: 2012/1/15 19:51
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| Durango_Boy | Re: Oil Pressure Fix - Need input | ||
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Elite Guru
 
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I'm almost thinking that at WOT, most of your oil is in the upper half of the engine and it's being pumped up faster than it can drain back down. This might be causing a starvation effect to the pickup and as it slurps air with oil the pressure drops.
The filter bypass is also a good place to check things out. What are you using right now? I might suggest, as long as others agree, that you need a larger capacity pan that holds more oil. |
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Posted on: 2012/1/15 19:53
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| Andrew | Re: Oil Pressure Fix - Need input | ||
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2013 Memorial Day Car Show Winner!
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I do know of the stock placement of the sending unit, but is there another port, so I can see the stock and manual gage at the same time?
I have never had the pan off of the block. I'm assuming a high volume oil pump, but not 100% sure.... I've also thought about the Canton, but not so much on the Accusump. If I decide to swap pans while I've got the stocker pulled, can I install the Canton without even lifting the motor a little? Turning the crank isn't a big deal, I just don't want to pull or even lift the motor if I don't have to. Thanks for all of the advice!! |
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Posted on: 2012/1/15 19:59
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_________________
2003 Atomic Orange Z06 Sold - 1996 Competition Yellow LT4 - DRM 383, NX N2O, Line Lock, LT Headers, 3" stainless exhaust, Power Effects, and many more mods SOLD 1996 Competition Yellow LT4 SOLD 1979 4 Speed with 383 |
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| Andrew | Re: Oil Pressure Fix - Need input | ||
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I am under the same impression that Bogus and DB are. Might need a new pan and am optimistically hoping for a cheaper solution of a bad sensor or clogged bypass. Might be time for a new pan.
Anyone know where I can get a Canton for less than $320? |
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Posted on: 2012/1/15 20:59
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_________________
2003 Atomic Orange Z06 Sold - 1996 Competition Yellow LT4 - DRM 383, NX N2O, Line Lock, LT Headers, 3" stainless exhaust, Power Effects, and many more mods SOLD 1996 Competition Yellow LT4 SOLD 1979 4 Speed with 383 |
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| bogus | Re: Oil Pressure Fix - Need input | ||
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Grand Imperial Pooh-Bah
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quite a few on ebay right now. type in "canton oil pan corvette"
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Posted on: 2012/1/15 21:04
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| rklessdriver | Re: Oil Pressure Fix - Need input | ||
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Senior Guru
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No other oil ports on the back of the block.
There is one above the oil filter but the oil temp sendor is screwed into that one. You could get a T and screw the gaugle into one end and the sensor into the other. On your problem. If you do happen to have the stock pan and a HV pump... Most likely what is happening is the pump is going in into bypass and dumping that bypassed oil in the area of the oil pump pick up causng cavitation. It's a pretty well known problem when the oiling system isn't set up for a HV pump. Will |
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Posted on: 2012/1/15 21:16
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1984 Corvette. 434 SBC with a Powerglide. Best pass - 8.48@160MPH 1.23 60ft on MT 275/60R15 Radials. 1972 Corvette. LS5 454 BBC with M20 4 speed. Best Pass - Doing good to just pass a gas station. |
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| Andrew | Re: Oil Pressure Fix - Need input | ||
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2013 Memorial Day Car Show Winner!
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Rklessdriver, would a new pan fix the cavitation issue or would more upgrades be needed?
The good news is that I can drive the car around without problems, just need to keep the revs down!! |
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Posted on: 2012/1/15 21:28
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_________________
2003 Atomic Orange Z06 Sold - 1996 Competition Yellow LT4 - DRM 383, NX N2O, Line Lock, LT Headers, 3" stainless exhaust, Power Effects, and many more mods SOLD 1996 Competition Yellow LT4 SOLD 1979 4 Speed with 383 |
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| tjpreul | Re: Oil Pressure Fix - Need input | ||
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Elite Guru
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Can the port on the side of the oil filter adaptor be used to put a guage in.
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Posted on: 2012/1/15 22:00
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_________________
Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| biggrizzly | Re: Oil Pressure Fix - Need input | ||
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I doubt you can install a new high volume pan without moving the engine a good deal. I have Champ 8 qt. Road Racing pan and it makes life a whole lot more difficult for many things.(starter removal for one). It is designed very similar to the Canton pan and I don't see you wriggling it up to the block through the existing frame rails and cross member. Also, if you have an automatic transmission the transmission lines need to be re-routed because the kick-outs for the larger pan are right in the way of the factory transmission line routing.
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Posted on: 2012/1/15 22:51
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| vetteoz | Re: Oil Pressure Fix - Need input | ||
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Quote:
Yes but IIRC you will need a reducer because hole is tapped 1/4"; not 1/8" like oil port at top rear of block |
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Posted on: 2012/1/15 23:00
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| bogus | Re: Oil Pressure Fix - Need input | ||
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Grand Imperial Pooh-Bah
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I agree with vetteoz. The port above the filter is for the oil temp sensor... not pressure.
The tap on the back of the block is for the oil pressure and oil pressure switch. The long one is for the pressure sensor, remove that one. The short one is for the switch and you need that for the fuel pump circuit - in case the fuel pump relay fails, it will keep the engine running. |
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Posted on: 2012/1/16 0:34
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| rklessdriver | Re: Oil Pressure Fix - Need input | ||
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Senior Guru
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Quote:
In the LTX that port is occupied by the Oil Temp sendor, so you would have to remove it. Will Quote:
Andrew It depends. If your hitting 60lbs at 3000RPM and by 4000RPM it's bypassing so hard that it's causing cavaitation - there is a real mi- match in the oiling system somewhere.... without knowing everything about the engine, it's difficult to pin point what the problem is. I'd say (after you verify the pressure drop with a manual gauge) get the pan off and see what pump it has in it, see what the pick up to sump clearance is, and see if the factory windage tray is installed. Once we find that stuff out it'll either be really easy to see the problem and fix it or a shot in the dark with a new pump and pan. Will |
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Posted on: 2012/1/16 0:37
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_________________
1984 Corvette. 434 SBC with a Powerglide. Best pass - 8.48@160MPH 1.23 60ft on MT 275/60R15 Radials. 1972 Corvette. LS5 454 BBC with M20 4 speed. Best Pass - Doing good to just pass a gas station. |
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| Andrew | Re: Oil Pressure Fix - Need input | ||
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2013 Memorial Day Car Show Winner!
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I have a buddy with a lift and jack tray, so getting the motor moved up a little isn't a big deal, I'd just rather not go that route. I'll check with a manual gage. If that isn't the problem, I'll pull the pan and get some pictures. How can I tell what pump is on the motor? Is there an easy way to tell?
Anyway, it will probably be 2 or 3 weeks until I'll be able to get the pan pulled. I'll keep ya'll updated. Thanks for all the advice and discussion!! |
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Posted on: 2012/1/16 0:59
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_________________
2003 Atomic Orange Z06 Sold - 1996 Competition Yellow LT4 - DRM 383, NX N2O, Line Lock, LT Headers, 3" stainless exhaust, Power Effects, and many more mods SOLD 1996 Competition Yellow LT4 SOLD 1979 4 Speed with 383 |
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| Durango_Boy | Re: Oil Pressure Fix - Need input | ||
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Elite Guru
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Quote:
The oil pump will have a model number stamped into the side of the casting. It might have a USA stamp, or a manufacturer stamp...depending on what it is. Do you know what shop built the engine? I seem to remember it was a Doug Rippie engine? Maybe contact that and see what pumps they prefer for their LT4 builds? Usually a builder like that will have a favorite they use. |
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Posted on: 2012/1/16 1:12
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| Andrew | Re: Oil Pressure Fix - Need input | ||
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2013 Memorial Day Car Show Winner!
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Quote:
Yep, it is a DRM build. I have communicated with Randy at DRM several times for a build sheet. They could not provide. They cannot track builds by VIN, only by the owner who had the work done, which I do not know... Great idea, I'll see if he can provide me what the preference is and that should give me a start. Thanks All! |
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Posted on: 2012/1/16 2:55
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_________________
2003 Atomic Orange Z06 Sold - 1996 Competition Yellow LT4 - DRM 383, NX N2O, Line Lock, LT Headers, 3" stainless exhaust, Power Effects, and many more mods SOLD 1996 Competition Yellow LT4 SOLD 1979 4 Speed with 383 |
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| Churchkey | Re: Oil Pressure Fix - Need input | ||
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Guru
 
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If you have the same results with another oil gauge you may be experiencing cavitation at the pump pick up.
Suggest modifing the pump pick up or build a new one. The problem is the stock 90* cut off at the pickup inlet which will cause cavitation. For a visual watch water as it drains from your bath tub. You want the inlet to be cut at a 45* angle then heat & roll the edge to form a flare. Get the pickup pointed at rear of the pan & 1/2" off the floor of the pan. Some SS screen material shapped like a bulb can be clamped to the pick up end. Luck. |
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Posted on: 2012/1/16 3:07
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| tjpreul | Re: Oil Pressure Fix - Need input | ||
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Elite Guru
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On my oil filter adaptor there is a port with a blank plug in it. Right above it on the block is another fitting. Could he use this one on the adaptor for his manual check.
It sounds like this is just going to confirm taking the pan off. |
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Posted on: 2012/1/16 4:32
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_________________
Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| bogus | Re: Oil Pressure Fix - Need input | ||
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Grand Imperial Pooh-Bah
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And this is why I am not a fan of high volume oil pumps. The standard flow works just fine for most street applications.
I am a fan of bigger oil pans, tho... extra volume, extra cooling capacity... all helps. And in a hard turn, less prone to starvation. Seems like cheap insurance to me. As for the fittings on the filter housing and above on the block. The one on the block should have the temp sensor in it. The one on the housing? That may have been a space for a potential cooler? I really don't know, but I do know it's rather large. I would just test at the back of the block where the system already tests from. Why add another variable? |
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Posted on: 2012/1/19 21:19
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_________________
The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| EngineDoctor | Re: Oil Pressure Fix - Need input | ||
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Master Guru
 
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The SBC oiling system will will perfectly fine with a stock oil pump for MOST applications, provided that your OIL CLEARANCES are within specs imho. I agree with Andy bigger capacity pan is good too
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Posted on: 2012/1/19 22:42
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| bogus | Re: Oil Pressure Fix - Need input | ||
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Grand Imperial Pooh-Bah
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Short of an all out racing engine, I agree with engineholic.
Then there is BrianCunningham's monster motor! |
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Posted on: 2012/1/20 0:44
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_________________
The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| Andrew | Re: Oil Pressure Fix - Need input | ||
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2013 Memorial Day Car Show Winner!
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This motor is made to rev to the moon. It is a street car and I normally drive the car very modestly. At what point is a hi volume pump needed?
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Posted on: 2012/1/20 1:03
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_________________
2003 Atomic Orange Z06 Sold - 1996 Competition Yellow LT4 - DRM 383, NX N2O, Line Lock, LT Headers, 3" stainless exhaust, Power Effects, and many more mods SOLD 1996 Competition Yellow LT4 SOLD 1979 4 Speed with 383 |
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| EngineDoctor | Re: Oil Pressure Fix - Need input | ||
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There are many factors involved here.... Basic rule of thumb is .001 thousands of oil clearance per vertical journal diameter.
Then I like to see 12pds of oil pressure per every thousand rpm's. For example, In an endurance racing engine running 7k at all times, at , full throttle 85pds of oil press. makes me happy, provided the oil gets back to the pan.... In other words 85pds at full throttle constantly, and at idle your o/p will drop to bout half that... In an application like this I run Hi volume modified pumps. all depends on watcha doin In closing if you dont know your oil clearances, you are kinda in the dark :/ IMHO. Regardless the more oil capacity you have and controlled oil temp. you have should be your objective. |
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Posted on: 2012/1/20 2:15
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| dan0617 | Re: Oil Pressure Fix - Need input | ||
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Senior Guru
 
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I bought a built used 383 one time and had this exact same problem. Was dropping oil pressure after about 3500 rpms at WOT. After about the 4th try I killed the bearings. I pulled the motor out, pulled the pan off, to find that there was no windage tray installed.
If you happen to pull the oil pan and find that there is no windage tray installed, that is your problem. If there is a windage tray, I would find out if that is indeed a high volume pump. If it is, I'd change to a standard volume high pressure pump. |
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Posted on: 2012/1/20 14:47
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ยด89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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