oil light flickering at high rpm

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jcarr210

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So I have a built 340 with aluminum heads lunati voodoo cam etc. and my oil light starts flickering at around 4k if I have my foot on the floor. I have an aftermarket autometer oil pressure gauge and when hot I get 35psi at idle 75 psi cruising and 90-95 psi full throttle to 6200rpm. I run 20w50 valvoline vr1 oil that's topped off too. I'm wondering if the oil light sender isn't getting a proper reading because the aftermarket sender is using a t-fitting along with it. Anyone have this problem? I've uploaded a pic of my setup.
 

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The factory light "switch" I'm used to seeing doesn't look anything like the one I'm seeing there.

Expect to see one like on the right in the Tee
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Hmm yeah mine sure doesn't look like that. Finding out what exactly I have down there might be the first step.
 
I would plumb a full mechanical gauge in to verify no oil pressure problems. Low pressure lights come on around 10 psi
 
That kinda oilweight should be in all out race engines or totally worn beater engines.
Why would you want 95 psi oilpressure in a freshly built engine with tight bearing clearances?

I would go down to 10w40 or even a 5 or 10w30-weight oil.
 
^^^ Yes, that is a good weight to possibly have flow issues somewhere. 95 psi is way more than needed; in fact all the pressure above are high. You can blow out a weak filter gasket at 95 psi.
 
Did you install a high volume oil pump during the build? If so, it may be draining the oil pan at higher RPMs and the heavier oil weight will be draining back slower than needed.

The first step is an accurate gauge to be sure this isn't a false reading.
 
Yeah I just continued to run what the previous owner was running. I have an old mechanical gauge around here somewhere that I never used. I'll try a thinner oil with a mechanical gauge and see what happens.

Other thing I forgot to mention is the builder used a fabricated Kevko oil pan. I doubt he built an engine and didn't use the correct pickup but now I'm wondering. I'm not sure what oil pump he used though.
 
Regardless light or mechanical gauge,the fact that its only at high rpm tells me your sucking air.
Cause could be pickup to far from bottom of pan,but more likely as said,if you have a h.v pump and thick oil it can't drain back fast enough.
Add an extra quart and drop to 10w-30 or 10w-40.
 
jcarr210 said:
Other thing I forgot to mention is the builder used a fabricated Kevko oil pan. I doubt he built an engine and didn't use the correct pickup but now I'm wondering. I'm not sure what oil pump he used though.
Click to expand...

So you had this engine built?

He didn't provide you with a detailed list of parts and what was done?
 
Regardless of "what's there" now I would get a mechanical gauge on it --if even temporarily--to see what it's really doing.
 
He has a gauge, says he has oil pressure, albeit a tad high from the heavy oil. He was asking about the light flickering.
 
It was built for the previous owner. I just have a huge stack of receipts. I just checked and it's a standard oil pump. Could I be low on oil with this kevko pan and an aftermarket dip stick even if it reads full?

I'm going to get a model number on the pan, find it's capacity, change the oil to little thinner, and hook up another oil pressure gauge.
 
Oil could also be foaming like crazy with those pressures. But that should show up at the gauge as a low(er) oil pressure.
 
I would find out the pan's capacity and go from there. Also, IMMEDIATELY after the light flickering, shut her down and pull the dipstick. If there's any foamy lookin oil......then there you go. A windage tray might be in order.

All this, including everything else here is only a guess however, since as far as I know, no one had perfected internet diagnosis skills.

I can say this. If "I" had a manual gauge on something WITHOUT a light and the gauge didn't show a pressure loss, "I" would "keep the hammer down".
 
BTW, I found the 2 prong switch that the OP has pictured; it is under the gauge sender in the pix. It is 2 lb switch from a Walters marine engine. The standard Mopar ones light at below 8-10 lbs. BTW, the response time of a gauge can vary; lights usually are very fast. So I would not ignore what the light is telling me.

If this switch is going off and is accurate, it says you have < 2lbs of pressure at that point in the engine. I have to wonder if the prior owner had a lot of light flickering with the 8 lb Mopar switch and put this 2 lb switch to reduce the number of times the light flickered! So be careful when you put in the lighter weight oil and look at the pressure immediately. The P.O. might have experienced an oil pressure problem and masked it with the heavy oil, either out of ignorance or on purpose.

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You know, maybe the little idiot light sensor you have just can't handle the higher pressures your throwing at it and it's spitting the dummy and flashing the light. You should consider that.
 
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