Many thanks to Jeff "Yardley" Holthenrichs for saving this vital piece of information. 1. Bowl Blend. Blend the bottom of your machined throat cut with the cast part of your bowl. Gently enlarge your bowl down deep in the bowl around the valve guide area. 2. Valve Guides. Grind on them and reduce their size quite a bit. They are sitting smack in the middle of one of the most critical areas of the port. On the intakes they dont hurt you too much because the direction of the flow is with the gentle, natural shape of the guide boss. On the exhaust they hurt you because the first thing the air sees is that abrupt flat machined surface at the top of the guide boss. Reduce it but dont completely remove it. 3. Short Side Radius. Lay it back, lay it back, lay it back!! With your fingertip you should be able to gently slide it from the seat all the way around to the crest of the floor and feel no sharp edges or abrupt changes. This should be a smooth natural roll or turn. 4. Crest Of The Floor. At the apex, or crest, you may want to reduce it some. Generally, grinding a little of the toip here greatly increases your cross-sectional area, probably at the most critical point of the window. 5. On the intakes, youll want to grind on the head bolt boss some to thin it and again increase your cross-sectional area. 6. Also on the intakes, youll want to grind on the pushrod side quite a bit and roll that short side WALL around and down gently to the seat. This is where your air flow velocity is the greatest. 7. Steps 5 and 6 are usually roughed in using a Bridgeport in an engine shop, then finished by hand. 8. On the exhaust, dont even touch that ugly reverse pocket in the bowl. Im talking about that area where the heat riser passages are on the two center ports. Every time you fill them in with clay on the flow bench, the flow picks up. So dont grind in there and make it worse. 9. As much as I would like for it to be a pure science, there is still an element of Black Magic to the feel for porting. It is somewhaT AN ART. 10. I will tell you that Newtons Laws of Motion certianly apply, especially the Law of Inertia with regards to wet flow. Also, Bernoullis Principle (Daniel 1700 1782) APPLIES. Study them. 11. If you decide to port your own heads, it would still be good to send them to a shop that has the capability to flow a Buick head accurately (mot all do), when you get done and have them checked and flowed. 12. Porting takes time. Lots of it. $800 ought to give you a lot of head porting time and a good flowing set of heads. Written and submitted by: Charlie Evans, GSCA Member Automotive Machine & Performance 6235 Highway 54 Philpot, KY 42366 888-624-3848
the standard abrasives site shows porting, but their guide features a step by step for the chevy heads. i've got the head porting kit and am ready to port and port match a set of 350 heads, but i've always wondered how well buick heads would come out following the "directions" for a chevy head. I'd have to think that most of the info would be applicable, but there are specific things that SA recommends such as unshrouding the exhaust valve (buicks seem to be pretty unshrouded from the factory), blending the short side radius a certain way, etc. Charlies info is timely and helpful, i'll have to dig into it abit before I get started. BTW, SA makes a recommendation for a 90* air grinder, but I bought the non-angled one. In hindsight I wish I would have bought the 90*, would have helped to get into corners when I was doing the block cleanup.
Mike, I think you'll find the straight grinder to work better! At the risk of over-stating the obvious, make sure you add goggles, a good mask, and ear muff style hearing protection!!!:Smarty: Putting a light at the end of the port that you're working on helps out a BUNCH too! If you want to really get fancy, get some grating for a bench top and custom build a bench. Put a fitting on there for your shop vac hose too!
