sp361t

I am having an issue with my OP when i get on the throttle. if i am in low grear and stand on it the OP will drop about 15 20 LBS. It will also drop if i am in 5th gear going about 50 and just hit the throttle hard enough to feel it.

There isent any bad noies and the oil filter and oil is clean

This is a new build 383 i have checked the Pickup level (New Pump and Pickup) and have tried 2 different pans and still no luck

other than the times metioned the car holds perfect OP driving, idleing ect.

I am starting to lean towards the Sending unit or the gadge its self. any other ideas would be very helpful

Thank you for your help

blackbear bob

mechanical guage or are you relying on the factory electric guage?

sp361t

right now i still have the factory setup in it i am working on getting a mecanical gadge in it verify the problem.

I was just curious if anyone else has had this issue

leesvet

Your filter mount contains a bypass valve that can hang open. It handles a LOT of oil...most of the oil in fact goes thru bypass to the top end so its unfltered...but this can show up as a pressure drop.

The pressure sender is famous for false readings. Clean the contact and if that does not help....change the pressure sender. Not the OP switch..the pressure sender. 2 different parts on the same fitting.

sp361t

i am in the middle of changing the sending unit right now mine had just a little oil around the connection area.

I dident think about the Bypass maybe when i hit the throttle it by passes too much oil

sp361t

i put a mecanical gage on last night and when i started it cold it read about 55 PSI, my old electical gage would read around 75 PSI.

I did not get a chance to drive it so i dont know if the drop in OP went away but the difference in pressure at itle is a intersting find

leesvet

FYI...

in the digital electrical display the default reading if the circuit is broken or disconnected is 80 psi.
So,
loose wire, dirty contacts, will show as increased pressure. This often causes an inverted reading of sorts where the more rpm (the thing gets a better signal) will show pressure going DOWN as rpm goes UP...weird. I've had it happen to me.
Being very annoyed and concerned whenever this happened, I relocated my oil pressure sender to the firewall next to the brake booster via hi-pressure hyd hoses and metal fittings so I can now easily remove a plug and install a mechanical gauge and/or swap out senders in 2 minutes or less.

sp361t

that is a good point the intersting thing is that this only happens when driving and when i kinda stab the throttle. i was thinking it was the oil getting away from the pickup untill it did it when i was in 5th gear going 50 and dident hit it that hard. maybe it is due to the torque of the motor or someting causing weird readings.

With the change in the op from electical to mecanical i am starting to think it is the sending unit i guess i will find out tonight

sp361t

i put a mecinacal gedge on it and there was a big difference when cold.
With the stock set up i would show about 75 PSI and when it warmed up i would show about 20 psi

Now with the mecainal gadge i show about 55 psi when cold and about 20 when warm. so thats a good sign that the sender is bad hopefuly it fixes my drop in OP when accerating.


Thanks for the insite

senorv47

I just recently had the same issue amd my mech changed out the oil pressure sensor an it fixed the issue.

WW7

You say this is a new 383?.. You should have more then 20 lbs pressure when warm unless the motor was built with a whole lot of clearence....My 383 has 70 cold and 45-50lbs warm on a mechanical gauge..
The type of OP drop your having where the OP drops when accelerating usually happens on older, higher mile motors when the bearings are very worn...Im not saying this is your problem, just that its where this type of pressure drop usually shows up..Hopefully the new sender will fix your pressure drop... ...WW

sp361t

Ww7
I agree but one thing i did not metion is i am using a cheapo gadge with the small plastic tube feed. my main concerin is the presure drop during acceration.

My car idles pretty low right now and if it just touch the throttle the Op jumps right up to like 40 or 50 so i do not belive i have a bearing issue or anything. i used stock clearences when i built the motor.

i have about 1200 miles on this motor so if i think if i was going to have a failure due to the build it would have happen by now

just the joys of hot rodding lol

Thank you for your insite

sp361t

well its true i still see a pressure drop under acceleration with the mecanical gage. guess i am going to have to break down and by a oil pan

mtnmanut

What oil are you running? i don't care if its a 265 c.i. 283 305 307 350 355 383 a small block is a small block. a oil pressure sending unit will not fix your pressure problem, just read correctly. 20 lbs at idle is pretty normal and kicking up to 50 with throttle. my concern would be the drop when you kick it in the ***. what does the mechanical gauge read when driving? if its still droping with the mechanical,i would head stright to the pump and the relief valve. just my 2 cents

sp361t

yes the mec. gage does the same thing as the elec. gage. when i go WOT in 1st gear my pressure drops thats the only time it drops is under heavy acceration.

I belive the issue is the oil is getting away from the pickup i am going to do what i should have dont in the first place and buy a pan with baffles in it.

That 383 TPI is a bad SOB low end.