oil pressure fluttering and dropping under load (400 hp+ fresh build with roller cam)
heres the build.
460 71 block and crank, edelbrock performer rpm heads, edel performer intake. hyd roller cam (ill dig up the specs if needed) roller tip rockers, hyperuetic pistons 10:1 compression. .030 over, balanced bottom end. high volume oil pump. stock rear sump pan. 750 truck avenger carb
heres what its doing.
800 miles on the engine.
I have a mechanicle gauge on it.
am running 10w 30 rottella
when the engine is cold my oil pressure sits at 65 psi (relief im guessing)
once the engine is warmed up my hot idel 750 rpm is around 20 psi and with a touch of the throttle i climb right up to 60 or there abouts. i go cruising down the highway and once up to speed my pressure will be 60 but as soon as i hit the throttle my gaiuge starts quivering and dropping back and forth to 35 psi, when i let off the gas my pressure comes back up, the same goes for coasting down a hill while coasting my pressure is 60 but one touch of the gas and pressure starts dropping and fluttering. its not an rpm cause its a load on the engine cause.
I just pulled the filter, the oil looks fine and the filter has a few specs in it. iv scene alot worse but there are a few in there im wodering if from just the engine breaking in.
wut ya'll reckon?
-gbm-
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77.5 camper special f250 (450 hp) 460 4x4 4spd braden 10,000 ib pto winch aftermarket steel steepside box. 700 watts worth of aircraft landing lights (driver)
79 camper special f250 2wd 429 auto (parts)
78 camper special f250 4x4 4spd ext cab 460 dana 60 front end (parts)
77 f150 300 I6 4x4 4spd (parts)
79 f150 300 I6 2wd 4spd (bought new in 79 by father, for resto one day)
Sounds more like a drain back issue which is causing the oil pan to not have enough oil in it at higher rpm. Try adding an extra quart of oil and see it if helps. It won't hurt an damn thing even if it isn't the problem. Why does everyone never worry about oil drain back while building their engine?
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Bear 45/70 Gimp Racing
“There are only two things stopping you, common sense and fear! And not much of the latter.”
Sounds more like a drain back issue which is causing the oil pan to not have enough oil in it at higher rpm. Try adding an extra quart of oil and see it if helps. It won't hurt an damn thing even if it isn't the problem. Why does everyone never worry about oil drain back while building their engine?
I will try this but I have my doubts as this issue is not rpm sensitive, I can be going down the highway at 2000 rpm coasting then hit the gas and it drops,
Its almost like as the engine loads up it thrusts to one side or the other and opens up a clearance, then i let off the gas and the truck drives the motor closing that clearance and pressure comes up.
-gbm-
__________________
77.5 camper special f250 (450 hp) 460 4x4 4spd braden 10,000 ib pto winch aftermarket steel steepside box. 700 watts worth of aircraft landing lights (driver)
79 camper special f250 2wd 429 auto (parts)
78 camper special f250 4x4 4spd ext cab 460 dana 60 front end (parts)
77 f150 300 I6 4x4 4spd (parts)
79 f150 300 I6 2wd 4spd (bought new in 79 by father, for resto one day)
Yes I think bear 45/70 is right, as you increase your revs your oil is being pumped out of your sump leaving it low on oil till it drains back, I use a large 8-9 litre sump on my 460ci & never have any oil problems.....
If the oil pressure drops imeadiatly on applying the throttle it sounds like loose main bearings. It would be a good idea to pull the pan and check clearences. The 370 in my F700 would drop 10 to 20 lbs psi when you would roll into the throttle , it was loose main bearings the thrust had way too much endplay. That motor was used hard and had many miles on it .
Good Luck ----- Hotwrench
__________________ FERGUSON'S GARAGE est. 1967 car , truck , heavy equiptment repairs 4 X 4 specialists PORTABLE WELDING SERVICE TOWING New @ used PARTS 1981 L 800 460 5 speed , 2 speed rear 1957 F 600 390 5 speed
If the oil pressure drops imeadiatly on applying the throttle it sounds like loose main bearings. It would be a good idea to pull the pan and check clearences. The 370 in my F700 would drop 10 to 20 lbs psi when you would roll into the throttle , it was loose main bearings the thrust had way too much endplay. That motor was used hard and had many miles on it .
Good Luck ----- Hotwrench
If the mains were loose enough to drop oil pressure they would rattle at part throttle.
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Bear 45/70 Gimp Racing
“There are only two things stopping you, common sense and fear! And not much of the latter.”
If the oil pressure drops imeadiatly on applying the throttle it sounds like loose main bearings. It would be a good idea to pull the pan and check clearences. The 370 in my F700 would drop 10 to 20 lbs psi when you would roll into the throttle , it was loose main bearings the thrust had way too much endplay. That motor was used hard and had many miles on it .
Good Luck ----- Hotwrench
The drop happens as soon as i get into it, its not rpm sensitive its load sensitive, like the thrust changes as the engine drives the truck opposed to the truck drives the engine. The shop says its normal, and doesnt really feel theres anything wrong.
-gbm-
__________________
77.5 camper special f250 (450 hp) 460 4x4 4spd braden 10,000 ib pto winch aftermarket steel steepside box. 700 watts worth of aircraft landing lights (driver)
79 camper special f250 2wd 429 auto (parts)
78 camper special f250 4x4 4spd ext cab 460 dana 60 front end (parts)
77 f150 300 I6 4x4 4spd (parts)
79 f150 300 I6 2wd 4spd (bought new in 79 by father, for resto one day)
If this doesn't change pull pan. Why did you run a hi volume pump? What type of pan did you run front sump/rear or 4wd pan. their are windage trays/crank scrapers available that really help on acceleration issues. I run a www.mpgheads.com windage/crank scraper. I run at steep angles often and need to clean off crank in odd situations. get the oil to the pump pickup as quick as possible. 4wd pan. My truck is for 4wd application. something to consider? Good luck.
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