Expert: Brad Sears - 7/14/2011

Question
have a 1957 chevy 327 engine auto trans the oil presure is 45 when you start the car and when the temp is 160 temostate openig the presure is 20 when you drive it goes to 25 to 30 depending how fast you go when i stop or pull in drive way it goes to 5 then i here a clunking buy the oil pan i had a new pump put in last year i recanged the oil this week i just did it in april no even 20 miles on it it was black and smelled ov gas so i adusted the carb edelbrock 600 to 1&5 turns out turned in to idel droped then back out half turn the pluges cleaned up idle is at 700 rpm the timming is set at 8 the car starts right up but when you step on it it suckes to much air is this air getting traped i the motor i had the radiator out and cleaned or is it the oil know useing 15w 40 was useing 10w 40 thought thicker oil would keep presure up only when oil is hot it knocks not when you drive is it the gas useing 93 octane donot know what else to do put oil cooler on the motor has chrome oil pan valve covers manifold timing cover is this making the motor to hot or is it the car runnig to lean have msd distibutor elctonic puges are campion 25ry17yc when you start back up after cooling about hour oil presure is 20 at idle and no kocking what is it  thank you  louie

Answer
Using a thicker oil is like a band aid on a cut that requires a stitch or two. Low oil pressure is either a defect in the oil pump or excessive Clarence in the rod bearings, main bearings, cam bearings or even a worn through spot on the bottom of a lifter. The other is that the rich condition caused by either fuel mixture or ignition problems could be thinning the oil out as unburned fuel runs down by the rings. With the modifications, aftermarket carburetor and ignition system, it is difficult to figure this out on this forum. I would need to check the timing at idle and at about 2,000 rpm, and stick an exhaust analyzer up the tail pipe.