10 minute porting.

After 15 minutes abs and the much improved 12 minutes abs.  I present 10 minute porting..

12g202 head

Just to show that the seat area is quite critical I simply put in a 5 minute three angle seat (little more than a freshen up) a valve with little more than 0.3mm backcut and a quick ”clean” using a small flap wheel ( and a big grinder) about 1 cm into the port. Takes little more than 10 minutes if even that.

It still looks pretty nasty and nothing like it would after proper porting.


Gains? .. not huge but significant ~3 CFM on 71 cfm total flow over the entire range of 3-12 mm lift  so about 5% on average gain.

Investment in time/effort: very little.

Next up is the chamber. But I will need a head gasket to see how far I can go.

Idea is to get some measure of pressure recovery and it will probably involve sinking the seat deeper in the head (yup..) and laying back the chamber but not cutting it all the way down to the bottom like Vizard suggests.

that i’ll be the 100 minute porting episode

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