WAYNES WORLD
Well-Known Member
Hello Everyone!
I have a fresh built 273 that idles with 75 lbs of oil pressure using 5-20 oil and will peg the 100 psi mech gauge before 2k rpm.
A little background information:
Rebuilt 66k mile never been apart motor. Decked .010. Stock 2 brl pistons. Stock bore, polished crank std bgrs miked and plastigauged. All clearances in spec. New rod bolts, big end sized, bgrs checked. Assembled with stretch gauge. Blocked was fully cleaned and all passage ways rodded.
New cam bgrs installed by machine shop with many years of Mopar experience. Mild (340 spec) Hyd cam. Custom length push rods.
Modified 302 heads, ported, slightly larger valves, cut .060. Using the original 273 adjustable rocker assemble. New locking adjusters. Slots located down, DS to the ft, PS to the firewall. Banana cuts to the bottom with the tiny holed pointing to the lifter galley.
Melling stock volume pump. (Actually 2 pumps thinking it may have been a pressure relief issue.) No change after second pump.
Autometer mech gauge and also tried a NIST traceable calibrated pressure gauge hoping it was a gauge issue. Surprisingly the Autometer was damn close.
Started out with the 30W break-in oil and had a blow out at the oil filter. Fixed the leak and ran fine but had nearly 100 psi above idle. Concerned with having a pump issue I dropped the pan and replaced the pump. New pump was dissembled, cleaned, lubed and installed. Added new K&N filter. Fresh 10-30 with break-in lube. Primmed right up. Still high. Switched to the 5-20 with the additive.
AF ratio is great, timing good and it runs great but if you tap the throttle up to 4k it spits a bit of oil out the rear main seal.
I pulled the valve covers off to recheck the position of the rocker shafts but they are correct. I have no trace of metal in the oil filters and no unusual sounds coming from the engine. When I pulled the plugs everything turns freely. I have about 200 miles on the motor at this point but nothing has changed so I need to get this figured out.
I was surprised when I took the valve covers off there was absolutely no oil under the cover itself, not even a film. No splash? I removed the DS shaft assembly and it did have oil in the shaft and there is no sigh of wear on the ball/cups or valve tips. They had oil on them.
I’m thinking maybe the cam bearing was clocked incorrectly?
Any ideas would be greatly appreciated.
Wayne
I have a fresh built 273 that idles with 75 lbs of oil pressure using 5-20 oil and will peg the 100 psi mech gauge before 2k rpm.
A little background information:
Rebuilt 66k mile never been apart motor. Decked .010. Stock 2 brl pistons. Stock bore, polished crank std bgrs miked and plastigauged. All clearances in spec. New rod bolts, big end sized, bgrs checked. Assembled with stretch gauge. Blocked was fully cleaned and all passage ways rodded.
New cam bgrs installed by machine shop with many years of Mopar experience. Mild (340 spec) Hyd cam. Custom length push rods.
Modified 302 heads, ported, slightly larger valves, cut .060. Using the original 273 adjustable rocker assemble. New locking adjusters. Slots located down, DS to the ft, PS to the firewall. Banana cuts to the bottom with the tiny holed pointing to the lifter galley.
Melling stock volume pump. (Actually 2 pumps thinking it may have been a pressure relief issue.) No change after second pump.
Autometer mech gauge and also tried a NIST traceable calibrated pressure gauge hoping it was a gauge issue. Surprisingly the Autometer was damn close.
Started out with the 30W break-in oil and had a blow out at the oil filter. Fixed the leak and ran fine but had nearly 100 psi above idle. Concerned with having a pump issue I dropped the pan and replaced the pump. New pump was dissembled, cleaned, lubed and installed. Added new K&N filter. Fresh 10-30 with break-in lube. Primmed right up. Still high. Switched to the 5-20 with the additive.
AF ratio is great, timing good and it runs great but if you tap the throttle up to 4k it spits a bit of oil out the rear main seal.
I pulled the valve covers off to recheck the position of the rocker shafts but they are correct. I have no trace of metal in the oil filters and no unusual sounds coming from the engine. When I pulled the plugs everything turns freely. I have about 200 miles on the motor at this point but nothing has changed so I need to get this figured out.
I was surprised when I took the valve covers off there was absolutely no oil under the cover itself, not even a film. No splash? I removed the DS shaft assembly and it did have oil in the shaft and there is no sigh of wear on the ball/cups or valve tips. They had oil on them.
I’m thinking maybe the cam bearing was clocked incorrectly?
Any ideas would be greatly appreciated.
Wayne