rubrhammer

iTrader: (5)

317 heads on LQ9 with LS6 cam and 99 Vette exhaust manifolds. Should I shape the exhaust port to match the gasket? The gasket hole is 1.74" and round. Ports obviously are not round. As is wouldn't this mismatch create turbulence and reduced flow in the manifold? Anyone have some drawings with dimensions of proven port configuration? Thanks guys. The threads I found were old and pics wouldn't come up.

truckdoug

iTrader: (25)

google the ls6 exhaust port shape, it's kind of a D shape.

customblackbird

iTrader: (2)

I wouldn't. Your not pushing the heads to there limits with the tiny LS6 cam. That difference with a compressed gasket isn't going to mess with anything. Opening the port up will slow velocity which is worse. Keep it as is and if you really want to help port shape right behind the valve seat and stem area to smooth it all out. If you want to polish the exhaust ports that can help with carbon buildup. Intakes you want alittle rough to mix air/fuel but the exhaust you want smooth.

I just did a mild port job on my 862s (5.3 boosted) and I didn't touch the exhaust port shape. all done right behind the valve and stem area and just polished the whole exhaust port. More work on the intake side removing swirl ramps etc.

farmington

iTrader: (14)

no. no. no no.