Blackcoog
Hard-core CEG'er
I'm going to swap another 3L in my Cougar. My 3L is burning a bit of oil (ring issues). I plan on doing a little extra porting on the new motor than I normally do. I was researching porting bits and I ran across this link:
http://www.vaglinks.com/Docs/Misc/SA-Motorsports.com_Basic_Head_Porting.pdf
I was going to gasket match the exhaust ports again but then I found this in the article above:
"In most cases, you never port match the exhausts. Many
stock exhaust manifolds and virtually all tube headers
will have larger port sizes than do the heads.You want
that "step" from the port to the larger header tube or
exhaust manifold because, as pressure pulses flow back
and forth in the exhaust system, it acts as a "reversion
dam" by resisting back flow of exhaust gases into the
port."
Is there any truth to that? Should I avoid opening up the exhaust ports? It sounds like I should stick to polishing them up and skip the exhaust port gasket match.
http://www.vaglinks.com/Docs/Misc/SA-Motorsports.com_Basic_Head_Porting.pdf
I was going to gasket match the exhaust ports again but then I found this in the article above:
"In most cases, you never port match the exhausts. Many
stock exhaust manifolds and virtually all tube headers
will have larger port sizes than do the heads.You want
that "step" from the port to the larger header tube or
exhaust manifold because, as pressure pulses flow back
and forth in the exhaust system, it acts as a "reversion
dam" by resisting back flow of exhaust gases into the
port."
Is there any truth to that? Should I avoid opening up the exhaust ports? It sounds like I should stick to polishing them up and skip the exhaust port gasket match.