From Harris Performance;
17. PCV Valves. A customer recently did some research on this after having issues with his engine and so I feel its something, I need to mention. most of you if you have a 350 and you go to a mild 350 upgrade will be fine with a stock 350 PCV valve. if you went from 4.3L or 305 to a 350 then you certainly need to change it as they are different. now if you have a 383 or 350 with at least a level 5 camshaft then you may need to use the PCV valve that GM uses in their ZZ383 crate engine.
GM Performance ZZ383 engine is recommended to use GM # 6487779 PCV valve, which cross references to Purolator # PV774.
Product Description
This PCV valve functions better with the lower vacuum signal of a performance engine using a camshaft with more duration and overlap.
PCV valves are not all calibrated the same, and perform differently depending upon the amount of vacuum an engine produces. A performance camshaft will typically produce a lower vacuum signal than the stock engine/camshaft, and the stock PCV valve may not close enough at idle, which can cause an irregular and/or high idle, or otherwise not function efficiently throughout the operating range of the engine. An improperly functioning PCV valve can also cause the premature break-down of engine oil, sludge build-up, leaking gaskets and seals, water vapor build-up, as well as allow excessive oil to enter the intake manifold. A PCV valve that closes too easily and completely, can stay closed too long above idle, and can also interfere with the proper evacuation of blow-by gases. This PCV valve functions better at a lower vacuum signal, but still opens once the engine vacuum changes during all-around operation. PCV valve starts to close ~1-2 in-hg
NOT USING THE CORRECT PCV VALVE will give driveability problems as well as oil leakage problems and consumption problems!!!!
17. PCV Valves. A customer recently did some research on this after having issues with his engine and so I feel its something, I need to mention. most of you if you have a 350 and you go to a mild 350 upgrade will be fine with a stock 350 PCV valve. if you went from 4.3L or 305 to a 350 then you certainly need to change it as they are different. now if you have a 383 or 350 with at least a level 5 camshaft then you may need to use the PCV valve that GM uses in their ZZ383 crate engine.
GM Performance ZZ383 engine is recommended to use GM # 6487779 PCV valve, which cross references to Purolator # PV774.
Product Description
This PCV valve functions better with the lower vacuum signal of a performance engine using a camshaft with more duration and overlap.
PCV valves are not all calibrated the same, and perform differently depending upon the amount of vacuum an engine produces. A performance camshaft will typically produce a lower vacuum signal than the stock engine/camshaft, and the stock PCV valve may not close enough at idle, which can cause an irregular and/or high idle, or otherwise not function efficiently throughout the operating range of the engine. An improperly functioning PCV valve can also cause the premature break-down of engine oil, sludge build-up, leaking gaskets and seals, water vapor build-up, as well as allow excessive oil to enter the intake manifold. A PCV valve that closes too easily and completely, can stay closed too long above idle, and can also interfere with the proper evacuation of blow-by gases. This PCV valve functions better at a lower vacuum signal, but still opens once the engine vacuum changes during all-around operation. PCV valve starts to close ~1-2 in-hg
NOT USING THE CORRECT PCV VALVE will give driveability problems as well as oil leakage problems and consumption problems!!!!
