I have a new 351w in my 86 f150 and it runs great but recently i changed from an edelbrock carb to a holley and after i did that ive noticed that sometimes my oil pressure gauge goes to zero for a second and then comes back up and at idle its 25 and goin down the road its arouond 50 but when i come to a stop or turn (sometimes not always) it drops to zero it didnt do this before with the edelbrock carb so idk if its the gauge or me being paranoid but its happenin. the oil gauge does leak a little bit and it did this ever since ive fired the motor up. ive driven it maybe 100 miles since i put the motor in and i started it the first time in august so im hopin its nothing serious just a gauge issue or a filter issue or something dumb. please help!!!!
also its not makin any noise or anything like that. im runnin royal purple 10w30 in it full synthetic and a fram high mileage. i started it for the first time with 5w30 in it for about 20 mins and then changed the oil to get it all out... howeverr i didnt change the filter.. before i even started it i ran the pump by a drill and had no issues oiling the motor it all looked good and i did this several times. any ideas???

 

Just a thought, but have you checked your oil level? I accidentally let the oil level get too low (by about two quarts... :\) in my Jeep Cherokee's 4.0L, and if I turned a corner or accelerated quickly, the oil pressure gauge was all over the place and dropped to zero occasionally. Once I topped it off, I've never had the problem again.

I'd also check the oil pressure sender to make sure it's installed tightly, and if your gauge is electric, that the wire from the sender to the gauge isn't damaged.

And maybe it's just me, but I'd suggest running a Wix or Motorcraft filter or something instead of Fram. I ran a normal Fram on my truck's 302 a number of years ago, and I got lower oil pressure with it (1/4 to middle of the stock gauge), than say a Motorcraft or Wix (with these I get at least 1/2 to 3/4 of the stock gauge). I've heard the Frams don't filter too well either.

Finally, are you sure your gauge is working properly?

 

i have a mechanical gauge in the car and it does leak a little bit but it worked fine up until the last week. so idk ive thought about changing the filter to a wix