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Please help with oilpressure fluctuation.

1870 Views 5 Replies 3 Participants Last post by  460Skywalker
searched all the oilpressure problems from old post, and havnt felt very sure about what is the problem or could be. This is my first built bbf and havnt had it to track , so its hard to no how it will do in 1/8 mile, but dont plan on finding out till something is done to help. I can accellerate easy in second gear around 3500-4500 for under 6-8 seconds or so and pressure will drop from 75 to 50 and bounce form 40# or so. This is after driving 3000 rpm or more for a minute which probably doesnt help. Have a canton fox swap pan and pick-up with canton screen windage tray, melling HV pump, 3/8 clearance pickup to pan. Had to move little bracket back one hole to where the cutout was for on screen. Heard it done before and thought that was weard since they were the same company. Might be flexing??. 3.5 on mains and 2.5- 2.7 on rods. Done all the oilmods to block and gaskets on right and holes not blocked,roller lifters in right. running 25/50 VR valvoline, no vacuum pump. Seems like pans being sucked dry and one quart didnt seem to help. Might be crank pulling oil up, Might pull intake and put in one restrictor to see if it helps. Lifters seem fairly tight in bores so didnt sleeve. I guess the restriction from them would of been good. Can still put in restrictor pushrods i guess. also first time i seen pressure drop it had pressure around 30 while slowing down and hit brakes hard and went to 0. Oil went to front of pan. Doesnt have a crankscraper of any kind just a little like flap in back to help keep oil from climbing up. I fairly sure it would make a 1/8 pass for 6 seconds at most but dont want to be wrong I wish i would have bought a better pan , Used to smallblocks and never had a problem with oil. Any advice would be appeciated..., Ed
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Could the oil be foaming from cruising from 3000 rpm? There was a slight mismatch in the heads return ports to block. Found it after shortblock was together and we didnt think it was too bad, maybe 1/4 to 1/3 of hole. I think i will get some restrictor pushrods and then work on the heads return passages. If motor comes out i am going to tighten mains to 2.5-3 thousands and tighten rods and install a stock pump. Maybe makes some oil control in pan. Sound like i am on the right track? I really rather not run a accumulater , but i will consider it..., ED
I bet you are putting all of your oil upstairs during the higher rpm cruising and its not draining back down to the pickup quite fast enough when you get on it. If that's the case you pick up some air at the oil pump and the pressure goes to sh!t.

I had to modify my Canton pan by drilling 5 1/2 inch holes in the solid windage tray built into the pan (front sump drag race 8 qt). This allowed oil raining down in the rear of the pan to continue down to the sump unobstructed while maintaining most of the pan's windage functionality. It definately helped in my case.

I thought about that but didnt know if 2800-3000 was high enough rpms to flow enough oil to make a oil return problem. I have heard the melling hV was a heck of a pump. If thats the case then the added oil temps and possibly foaming from sucking air. I didnt want to do a burnout, stage car leave on brake and in middle of wheelie have no oil pressure. I guess i will forget the transbrake at first, lol. Thanks , I guess i will pull baffles in valve cover and check for oil filling up. This would be great if it does fine at track, Its hard finding anything out anywhere else,,, ED
Sucking air somewhere.
yes, it is, i think i will find a big drill and pull distributer and see if i can find out for sure .
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