KYWes

My '95Z has the oil pressure switch located on top of the engine block after the end of the intake manifold. Where is this oil port in the overall oil flow of the engine? That is is it reading immediately after the oil comes out of the pump, somewhere in between, or in the return flow to the pump.

Secondly, what about the port above the oil filter. Where is it in the oil flow line?

This question came up from a customer about his '70 454 Chevelle. He was wondering where the oil pressure reading is taken. If someone knows the info on the 454 I'd appreciate that answer too.

Injuneer

The best reference is in the 94 factory manual (just the one I had handy - all years should be the same), Volume 1 of 2, Part 1 of 2, Page 6A3B-9, showing the oil flow from the back of the engine view.

Essentially, the oil from the pump flows into the center of the oil filter, out the holes around the top of the filter, and back into the block immediately adjacent to the lower oil pressure port. The oil turns back toward the crank, with a portion of the oil taken off to lubricate the crank bearings, and balance of the flow moving upward, directly to the upper port. Just below the upper port, the oil branches off to the cam bearings.

In effect, the lower and upper ports should be very close to each other in pressure. The upper port will have a slightly lower pressure, reflecting the frictional flow losses between the lower port and the upper port.



No idea how the big block is set up.

Minor point, but it's not a "switch", it's a "sensor".

KYWes

Excellent! Thanks.

Yeah, I figured I should have said sensor. Thanks for the correction. LOL

TGGodfrey

I have seen 70's big blocks in 2 locations both were right off the oil filter housing. You were reading the pressure coming out of the Oil filter.