I will go to the flange size on the ports, regardless of the gasket size.

The guy that did the fully ported head in the pictures has R&D'd it with a flow bench to get to that shape, so it's what the air wants in this setup. Remember the valves are also canted at 14 off vertical, so the air is definitely racing towards that part of the chamber.

I took a dial indicator and some calibrated rocks and set the intake valves at 0.438" lift, which is how much lift my current cam has to show the difference. It was recommended to me, if I can, to get 0.020" shaved off the bottom of the head if I can. Hmm, I may try that after I port and re-shape the chamber on my running head, I'll see if the Machine Shop in Elko (2.5 hours away..) can shave the head in the same day. In the past they have been able to do same day work for me when scheduling it in. I need to run some numbers, but l don't think it's possible to bring the compression up too high from shaving the head while using a head gasket that is around .030" thicker than the stock steel shim gasket that is impossible to get now.

I adjusted the color for more contrast because the sun was white washing it out.


Then I brought it indoors. See that step in the chamber above the intake valve? That step is what lowers the compression, the 4bbl head doesn't have that step. So I will likely smooth that step out around the intake as well.


You can see where I was working with the dial indicator as it scrapped the carbon off the valve on the right. I just shifted the set up left to do the other valve.


Edited by TheSilverBuick (05/26/14 01:54 PM)
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo