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Old 01-30-2013, 09:32 AM
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Quote:
Originally Posted by ap72 View Post
20psi at 1500 RPM is NOT that low. its below average for a new crate engine but many people have built engines with this pressure or less. I'm tempted to think he reused the oil pump and a worn oil pump will have such a poor seal that it will have little pressure at low speeds- the other option is that he is just running larger clearances, and at one time that was a VERY common thing to do.

I wouldn't go too much thicker and I'd give serious thought to buying a better pump (m155hv from melling is about $40 without the pickup, which is about another $10). You may have other issues (leaky pick up, clogged pick up, leaking oil main, etc.) but it is possible for everything to be fine and just have low oil pressure if you have large rod, and main, or lifter, or cam clearances.
I'll see how it does with the new filter and oil but I may end up changin the pump. I have a change the pan gasket anyway cause its leaking a little. I can't remeber what pump I used or if I even changed it. Its was a while ago. I had a thought that maybe I left out the gasket that seals the pump to the block? Seems like it could cause this problem. I don't know how I could get the pan off with it in the car though.. For the pump I would think I could pull the old one out and let the drive shaft drop out with it, then just put the shaft on the new pump and slide it up in. This way I wont have to do anything from above.

Quote:
Originally Posted by snakebit68 View Post
Just my opinion...but I think adding thicker oil to boost pressure would only be masking a more serious issue. Low oil pressure is an indication of an underlying issue. First, make sure your sending unit is functioning properly and then verify your gauge is reading correctly. If so, its time to open it up and check oil returns, pump pickup, oil pump...and then on to clearances. But don't ignore it. My buddy tried the thicker oil trick to boost pressure...it worked...until he made a pass at the track and it seems the thicker oil was unable to return to the pan fast enough at 7000 RPMs and "BANG". There are alot of details and steps involved to diagnosing your issue...but don't put a bandaid on it, please.
Just my opinion...no better then anyone else's
I'm not looking to mask the problem. But if going from 30 to 40 weight oil will fix it I don't think that's really considered masking it.

Quote:
Originally Posted by snakebit68 View Post
I was a little struck by the fact that you stated your engine was bored .080 over. I was under the impression that a 383 is a 350 block that is .030 over with a 400 crank and flywheel...bringing the cubic inches to 383. If your block is .080 over you may never get good oil pressure. I believe the limitations on boring a 350 block border around .060 and that is pushing the cylinder wall dangerously close to being to thin. Those cylinder walls are surrounded by water jackets, ports in the block that allow coolant to dissapate the heat of the cylinders. Are you certain of the bore?
Wrong thread lol
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