Join Date: Dec 2012
Location: Gastonia, NC - Born & raised in Connecticut - 31 years
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I think any good machinist can do the job. Your trouble seems to come about when they try to rebuild the Pontiac like a Chevy, or Ford, or...... in that the pontiac has a different approach in producing power - build for lower RPM torque whereas a Chevy uses higher RPM horsepower.
The main stumbling blocks are the cam and the heads. You want a Pontiac grind cam having a dual pattern - either more lift, more flow, or both, on the exhaust side to get the gasses out. If your builder recommends a single pattern cam because he builds chevy engines where the intake/exhaust pattern is the same, then it won't optimize the cylinder flow and you'll have poor results. Stick with a factory grind and you will be safe.
With regards to the heads, the valve seat angles are different and you don't want a chevy guy grinding the seat/valves aka chevy specs because he thinks they will work better. A good 3-angle Pontiac valve grind is a real performance improver and should be done. Some will recommend installing hardened valve seats to better handle the unleaded fuel or your valve will sink into the head. My opinion, and I am not a machinist or everyday engine builder, is they are not needed unless there is minimal material at the valve seat diameter (ie several valve jobs) leaving little edge/margin for the valve to hang on to. Super high valve spring pressures and radical lift cams could probably benefit from hardened seat as well as roller cams with their fast and aggressive lift and slam close properties, and heavy nitrous use. For near stock or a little hotter build I think stainless steel valves are a must, and a good margin of valve edge hanging past the valve port opening, plus reasonable spring pressure, bronze valve guides to ensure the valves are straight & centered as opposed to trying to skimp and go with the old guides or knurl them. I suspect you won't be using it as a daily driver either.
You also want the hi-performance 60psi oil pump from Mellings. It was used in the GTO. There was a lesser pump use in the big cars, but essentially you machinist should be able to get the right one, or you can buy it yourself. I bought the blueprinted 60psi pump from Butler which is indeed more money, but it is insurance that I will not have to worry about pump pressures. Don't get me wrong, the Mellings 60psi pump is a great piece and works just fine and is used in most rebuilds, so don't be afraid to use it. Do not use the 80psi pump for street.
There are other optional improvements for your rebuild, but it all depends on what you expect out of your engine. If you are going stock, then you don't need to do a whole lot. $12,000 for rebuild has got to be for a high HP race prepped trun-key drop-in 461 CI using all new parts, and even then, that seems a lot to me using iron heads.