11/2 or 15/8 primary tube? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

pkj · 08-26-2006, 08:47 AM

i am doing the headers now, but need help on the primary tube size. 68 truck
i have stock 307 that i am planning on keeping for 1 to 2 more years. then i will put 400 with 906 vortec heads in. either way i want to keep the torque up. i have decided on full length ceramic coated hooker comps. exhaust pipes 21/2 non manderal bends, H pipe, exit rear of truck, 3 chamber type mufflers. now i have been wondering about that old/new thread in engines 307 strocker. so i need a compromise keeping in mind i may not go with the 400, but will for sure use a vortec head. any suggestions?

08-26-2006, 08:47 AM	#1
pkj Senior Member Join Date: Jun 2006 Location: waycross ga. Posts: 438	11/2 or 15/8 primary tube? i am doing the headers now, but need help on the primary tube size. 68 truck i have stock 307 that i am planning on keeping for 1 to 2 more years. then i will put 400 with 906 vortec heads in. either way i want to keep the torque up. i have decided on full length ceramic coated hooker comps. exhaust pipes 21/2 non manderal bends, H pipe, exit rear of truck, 3 chamber type mufflers. now i have been wondering about that old/new thread in engines 307 strocker. so i need a compromise keeping in mind i may not go with the 400, but will for sure use a vortec head. any suggestions?



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.