Join Date: Dec 2012
Location: Gastonia, NC - Born & raised in Connecticut - 31 years
Mentioned: 1 Post(s)
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The 670 heads have a closed chamber design and 72cc chamber. Rated by many as to be one of the best flowing intake passages -stock. But, being closed chamber, I'd skip them. You want to use the 061's. It too is listed as 72cc's. The 061's were the first of the open chamber heads AND the chamber is pretty darn close to the Ram Air II, IV, HO, & SD chambers. If you put them alongside any other open chamber heads, you will see that the other heads have a deeper set chamber. Should promote a better burn. Both heads have the 2.11/1.77 valves, but 067 heads have the screw in studs. The 061 has press in studs and the AIR holes in the port pockets. I have a set that I plan on using on my 462 engine if they pass the machine shop inspection. I want them because of the chamber configuration. I will add the screw in studs. There are a couple options to add these which I found on the internet, but your machinist should be able to work with you on this. I will also be doing my own port matching/polishing etc.. Get Jim Hand's Pontiac (Got mine on Amazon) if you think you might want to tackle this yourself as the book guides you through the process. In my build, I am looking at the forged pistons having a dish in them to lower that compression as well. I am also going with forged rods which is not that much more when you consider reconditioning the stock cast rods. Cast pistons and rods are fine if you can keep your RPM's to the factory redline and don't hammer it all the time. Me, I like to wail on my cars, so I go with a little more insurance. Cam choice is wide open and everyone has an opinion. The factory knew what they were doing and made great grinds. Each cam grinder seems to have his/her take on what is best, what RPM range, needed engine parts, gear rations to use, etc.. -very confusing to say the least. You want to match up your car weight, trans & rear gear ratio, tire size, and the RPM range you want your motor to spin. Now you can grind a cam for torque or HP, lower, mid, & upper ranges, so you again want to match it to your car specs and your driving requirements. I always build a Pontiac for torque, but know a lot of torque spins those tires easily, especially in wet road conditions. You can move the torque range up or down depending on your cam selection. Seems most grinds are on a 110 LSA centerline while the factory was nearer to 113 LSA. The 113 LSA gives a broader power range over all. So another consideration. So, you really have to put some thought into a cam. My selection is on a 112 LSA. Be careful on some of these blogs/forums because it seems just about everybody is a camshaft technologist and will quote flow number, theory, and computer dyno programs. Again, Jim Hand's book is very helpful here and gives comparative facts based on his 467 CI street/strip '71 Lemans wagon. This book also has 13 pages of Pontiac engine builders engine combinations with CI sizes, estimated 1/4 mile times, engine parts selection, cam specs, etc. that can be very useful to any Pontiac engine build. I have an assortment of Pontiac engine building books/guides going back into the '70's and Jim Hand's book is a contemporary printing with all the good info you need to know to produce a solid running performer.