Oil Pressure
03-21-2005, 05:35 PM
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Oil Pressure
I have a 60 psi oil pressure gage in my 63 swc that reads 60 + cold, 58 - 60 on the interstate, and 30 - 40 at idle hot. Is this normal or should the cold and interstate readings be lower?
03-21-2005, 09:46 PM
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Depends. Very late production SHP/FI engines got a 55-60 psi relief spring, and this should have been accompanied by a new cluster assembly with an 80 psi gage. Earlier SHP/FI had a 60 psi gage and a 40-45 psi relief spring, as did the 250/300 HP engines and all earlier SBs, so most C1/C2 era Corvettes had a 40-45 psi relief spring in the oil pump.
So what's your sequence number?
Duke
So what's your sequence number?
Duke
Last edited by SWCDuke; 03-21-2005 at 09:54 PM.
03-21-2005, 10:24 PM
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Pardon the ignorance, but what is the sequence number and where do I find it? The only number I know is the VIN and that is 30837S103388. It is a 327/300 and is not FI.
03-21-2005, 10:40 PM
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Sequence number is the last five digits of your VIN. You have a fairly early car which predates the change of increased oil pressure, which only applied to 340/360 HP engines, anyway.
So someone either replaced the oil pump with one with a high pressure spring or installed a high pressure spring in the existing oil pump. Either way it's totally unnecessary on a medium performance engine and only marginally necessary on a high revving mechanical lifter engine.
On the other hand it will do no harm other than maybe making the oil run a little hotter and increasing parasitic loss a bit.
Duke
So someone either replaced the oil pump with one with a high pressure spring or installed a high pressure spring in the existing oil pump. Either way it's totally unnecessary on a medium performance engine and only marginally necessary on a high revving mechanical lifter engine.
On the other hand it will do no harm other than maybe making the oil run a little hotter and increasing parasitic loss a bit.
Duke
03-21-2005, 11:09 PM
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Thanks, I don't know what parasitic loss refers to in this case, but if the pressures I'm experiencing are not hurting anything, I am darn sure not noticing any loss of anything. This thing is has me grinning from ear to ear every time I drive it.
03-21-2005, 11:35 PM
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Parastic loss includes internal engine friction and the power required to drive essential accessories like the water pump, oil pump, and distributor. The higher the oil pressure, the more power it takes to drive the oil pump. Same applies to water pumps - "high flow" aftermarket pumps absorb more power and are not necessary for engine cooling.
Decreased oil pressure was a "trick" used by some manufacturers to get better fuel economy numbers for the low revving emission controlled engines from the seventies. Some only generated 5 psi at idle and 20 psi maximum pressure.
The 327/300 is an excellent engine - gobs of low end torque!
Duke
Decreased oil pressure was a "trick" used by some manufacturers to get better fuel economy numbers for the low revving emission controlled engines from the seventies. Some only generated 5 psi at idle and 20 psi maximum pressure.
The 327/300 is an excellent engine - gobs of low end torque!
Duke