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Discussion Starter #1
Hi Guys,

I’m not far away from doing some porting/head work on my 2L head and I’m trying to decide whether to take the “do it yourself and hopefully very rewarding road” or getting a machine shop to do the work and pay the $$.

I will be using Richard Jemisons porting method, so I’m really hoping Richard will join in and help put my mind at ease.

To start with, when using the 75 degree cutter to open the valve seat and throat, is a concentricity gauge essential to ensure the Neway pilot/cutter is in concentricity with the valve seat ?

My way of thinking is if the Neway pilot is not in line with the valve guide and not concentric with the valve seat, the 75 degree cut will be offset.

Then, once the new valve guides are installed, and we are at the reaming process, is it ok to do this process by hand and do need a drill press and properly take concentricity into account to ensure the valve guide and valve seat are inline?

(Also, when new guides are installed with a heated head and chilled guides) is there any play which can affect the concentricity between the valve guide and the valve seat?)

Finally, once the new valve guides are in place, and the Neway pilot is again placed in the valve guide (for the 30 degree cut), is a concentricity gauge needed to ensure the pilot is concentric with the valve guide and seat? (Otherwise I feel the 30 degree cut will be offset and the valve and seat will not have proper contact)

So in short I’m concerned that by being out a little bit here and there, it’s going to make a big difference when it comes to trying to lap the valves in the seats.

I would really appreciate it if anyone with experience in this area could tell me your thoughts and help me make a final decision as to whether I should do this job myself or leave it to a machine shop.


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