here's the skinny: freshly stroked 383, high volume oil pump, mechanical oil guage and fully functioning original idiot light. moroso 7 qt stroker pan with baffles, scraper, and windage tray. my oil pressure momentarily (up to 2 seconds) drops to 5 to zero psi on some, but not all of my hard decelerations. it only happens when i come to a complete stop right after having my right foot good and in it. the oil light will flicker (up to 2 seconds as well), providing my second opinion. all other oiling functions are fine. concurrently, the car will sometimes stumble to 400ish rpm and has yet to die, but quickly recovers. even when it's full hot, the oil will quickly jump back up to 20-25psi and idles at 700 rpm in gear. is the oil pressure drop because of a fuel starvation? or is the demand of the brake booster causing the low rpm that reduces vacuum which removes advance (compounding the issue) and causes the drop in oil pressure, or is the lack of oil pressure causing a drop in rpm? how worried should i be? my car is still in the tuning stage, so it's rarely driven around town while i check things out. it only happens every now and then and it's sometimes hard to reproduce intentionally, meaning i stop the same way and will get different results. any thoughts?

John J
I had a 90something Kawasaki Vulcan 1500 V Twin that if I hit the brakes really hard the oil light came on. No accompanying rpm loss. It was inertia causing the oil to not be in the bottom of the engine. No damage. Rarely occured and only briefly. And by it's nature it occurs during no load. I survived owning this machine, and it survived my brain which has an on/off switch inverse to a motorcycle's:D

I had an 87 Caddy with a 4 quart pan. Same thing. My solution was to not brake as hard unless it was an emergency.

My 412 has great oil pressure. Similar oil pan to you with the trap door etc. I did some brake work last year and decided to see how good my brakes were, at the track.
Crossed the line at 125mph and hit the brakes pretty daggum hard. Good brakes. Just happened to glance at OP as I let off brakes and saw OP rising from 10. WOW, not supposed to happen with a trap door is it? I don't think the trap doors work. Think about it, under acceleration and with oil return, the flap is angled to the rear. Hard decel, which moves faster to the front... hot oil or a bearingless flapper?
Some oil will definitely be on the front side of the flapper, and some oil will be on the top of the front half of the engine. The flapper is not a perfect seal either, and oil being pushed to the front will escape it. And if it is a perfect seal, your lube system is pumping oil into the front half of the engine and if the trapdoor is forwrd it can't return can it? It would have to reach an equilibrium where the weight of the oil on the front minus inertia overcame the weight of the oil on the rear + inertia: OR MOSTLY ON THE FRONT.
Either that or my trapdoor is defective, Idunno. Can't remember if it has any holes in it but it needs some. Maybe also the guys that don't like high volume pumps are right and have input. Idunno. I am going to buy a cheapo vid camera and mount it so it catches OP during my runs, cuz I never look at it. Having too much fun to care about OP. I console myself that my oil filter is clean, I use synthetic, and it occurs at no load.

Your RPM loss may be from inertia moving the fuel in your primary bowl away from the idle wells inlet. Actually the fuel continues going forward and the carb is slowing down.

Edit: I am not really consoled by any of the aforementioned things. I don't want my engine to operate without oil, not this engine. That's why the camera. If I have to install a scavenging oil pump to fight Mother Nature on this one, then so be it. She will probly have another trick up her sleeve that I forgot. Oh well

Check your oil pressure line to your gauge.
I had a similar problem due to the line leaking at the gauge connection.
Almost cost me an engine.

guccieng!!!! You're suppose to capitalize "i"!;)

Seriously, that was well written. Fun too. So why that choice of oil pan? Sounds like they left out a baffle. I wouldn't be too concerned. It's not happening under much of a load.
Oh, one more thing; What Tim said!

guccieng!!!! You're suppose to capitalize "i"!;)

Seriously, that was well written. Fun too. So why that choice of oil pan? Sounds like they left out a baffle. I wouldn't be too concerned. It's not happening under much of a load.
Oh, one more thing; What Tim said!

sorry about the "i's"! anyway, i took it to work today (110 mile round trip, got over 15mpg w/o overdrive:hurray:!), and had the oil light come on only 3 times at stop lights, and i noticed it was only when the rpm's took a dive, not so much how hard i brake. if i pump the brake pedal very aggressively, the oil pressure doesn't fall below 5-7 psi, but if it's a constant pedal, even not as aggressive as before, the rpm's fall to 500ish, and the light comes on with a second or two of zero pressure. i'm almost convinced this is a brake booster issue (11 inch single diaphragm delco moraine) causing a loss of vacuum, or fuel starvation. i have a holley street avenger 670, vac sec., electric choke, that pulls 13 inches of vac at idle in gear, 6.5 power valve, 70 jets, dyno-tuned (vac advance can is the echlin 1810, all in at 8 inches). do these carbs have issues with fuel starvation on hard stops? is pumping the brake allowing the vacuum to 'catch up' or the fuel to slosh around allowing the better idle when i come to a stop? this is less of an issue when the car is heat soaked, idling at 800ish. any other opinions?

schoon: definitely not leaking at the gauge. i would have dripped all over my right leg! the back of the block looks good, too.

edit: i just found something interesting on the pro-touring.com site: secondary drip causing flooding on hard stops? so it could be fuel starvation or flooding? jeesh... makes me want to hire a carb guy and not worry about it so much! and i still can't find a definative answer to the power valve question: half the idle vacuum or 2 inches lower?

it's not the vacuum. i disconnected the booster and plugged the line and was actually able to stall the car this time. so we're down to fuel flood or starvation, or bad baffling? any other opinions? anything else i can try?

i'm an idiot! it was low oil level all along. you see, the dipstick was scribed by my engine builder to mark the level for the custom dipstick and 7-quart moroso stroker pan. the last oil change guys probably didn't notice the scribe (which is 3/4 inch higher) and used the printed level line (or put 6 quarts in and thought it was good). i obviously made that mistake too, with a wet dipstick in a dim garage. this afternoon i noticed the scribe, put 2 quarts in and can't get the oil light to come on if i try. boy do i feel stupid! thanks for everyone's input.

...it was low oil level all along. ...the last oil change guys probably didn't notice the scribe...

You mean you let the lube places change oil in your 383. OMG :clonk: Watch those guys...they can cost you a bundle with their silly mistakes. The horror.

Glad you got it figured out.

Guccieng, I agree with dnult. Why in the *&#@ do you take your car to quickie lube? Do you really want somebody with a 6th grade education even touching your car? Man, learn how to do it yourself, or take it to a real mechanic for service. The chain lube places budget for paying out for destroyed engines, if that tells you anything.

i do it because it costs as much and is more of a pain to do it at home. i remember growing up in texas, we'd throw old oil on a trash and yard debris pile and light it up! here in cali, it's not worth the mess to take it to someone. the quickie place i use lets me walk through the stall with the car, cuz the kids are always drooling over the car and asking me questions. i bring my own oil and filter and pay the 16 bucks in labor. the mistake they made once and i made twice was incorrectly reading a scribed line above a stamped set of lines on the dipstick, which let to my problems in this thread. all in all, i don't leave my car unnattended with anyone but the engine builder and the dyno-tuner. otherwise, i'm standing right there with it.

I guess your value of worth is only considering the up-front cost. It is relatively cheap to have someone else deal with the headache of changing your oil. There is also a cost associated with someone messing up your stuff. From what I've seen, the odds of the oil changers making a mistake is far higher than it should be. If I've had my oil changed 20 times in recent years, I can safely say I've discovered no fewer than 6 foul-ups which caused me to drag out the cardboard and do it myself.