RallyJon

With nice, new, better material, perfectly fitted valve guides, won't there be a lot less chance of the ports clogging again?

InTheAir

Theoretically, yes.

The SAI ports extend to just downstream of the exhaust valves. If the SAI check valve gets stuck open, any exhaust can flow up the SAI ports. The amount of "stuff" (carbon, oil, etc.; excuse my shorthand) that can be deposited in the SAI ports is proportional to what "stuff" is in the exhaust. Therefore, if the guides are worn and oil is getting into the combustion chamber, then the exhaust will have more unburned oil that could increase your chances of clogging the SAI ports.

However, even if the car doesn't have worn valve guides, there is still "stuff" (i.e. carbon, etc.) in the exhaust that could be deposited, albeit less.

Therefore, having perfect guides doesn't mean you won't clog the SAI ports. However, having imperfect guides could conceivably lead to quicker clogging due to more "stuff" being in the exhaust.

AndyK

So to be sure to avoid these issues, I'll have to search for a car that has never seen snow, rain, or the road!?