Thanks for your input Jim ... do you do valve jobs chamber mods and porting on Pontiac heads as a business? Forgive me I think you may have told me before. I used to spend more time on this forum and have always enjoyed my time here. I have 3 different engines on my table Im trying to work at this point but keeping my worker bees going and life in general continually interferes. The Chev 302 concoction a Poncho 350 concoction and an 87 Sportster concoction. Solid rotating assy's lightened as possible, great heads matched to appropriate cams cams with quality valve-train. Have used track Fastburns for the Chev - CC Mag 268 solid , NOS 86 1100 bathtubs - Andrews .536 for the sporty. For the Poncho ... I need heads to match up with a Lunati lift rules RL-067 cam .256 I, .262 E @.050 , 108 lobe separation 2 degree advance... intake open/close 22 54, exhaust 61 21. Victor and Hooker Super Comp with 800DP carb or Holley Q-jet DP, the large one. Motor will feature BillMiller 500 aluminum rods and a nitrided factory N-crank slightly destroked to make 365ci if I can go the 4.000. Manicured fillets for the 2.100 rod journals.
One of the things I liked about the Fastburn/302 combo was the the super low-lift flow numbers as well as the swirl and would be trying to emulate that with the Poncho. I have read the 670 head is noticeably better at low lift than other iron d-ports and was wondering if the closed chamber might be a better choice for my project as the cam is not going to be high lift (close to or under .500) I have one set of rough 670's but they were the original set on my best 4-bolt 428 block Id like to save. Cam range is 4000-7000 supposedly do have a set of Rhoads lifters. Might go for the newer version of these, the cam is hydraulic although a solid might be more appropriate. This motor will most likely need ported heads. The block is 69 ... hoping it will take 4.000 bore. What would be your min sonic wall thickness? I was thinking .100 ??? Is there a way of porting or modifying a d-ports to make it swirl?