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#1 |
Senior Member
Join Date: Jun 2006
Location: waycross ga.
Posts: 438
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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? |
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#2 |
Registered User
Join Date: Jul 2000
Location: NC
Posts: 987
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Re: 11/2 or 15/8 primary tube?
I am not familiar with the heads you are using, however, I am building a 406 and plan on needing 1.75" headers. Since you may change your mind on the engine, I think it would be a mistake to buy the headers before you decide on the engine. A chicken before the egg kind of thing....
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#3 |
67-72 Addict!
Join Date: Feb 2002
Location: The TAX State!
Posts: 7,857
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Re: 11/2 or 15/8 primary tube?
I would go with the larger headers since you are planning some type of bigger engine in the near future.
__________________
Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads |
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#4 |
Senior Member
Join Date: Jun 2006
Location: waycross ga.
Posts: 438
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Re: 11/2 or 15/8 primary tube?
thanks never sure what i will do in future so i guess i will go with the 1 5/8 primary hooker comps. what about exhaust pipe size? 2 1/2 kink bend over kill?
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#5 |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: 11/2 or 15/8 primary tube?
1 5/8 " primarys are fine on a mild "street" 383 or 406, & 2 1/2" pipes are about right on for the big inch sb mills......on the 307, I would say 2" pipe tho.....2 1/4 MAX. There is no "free lunch" , if you want to build it once, build it after the 406 is planted.....
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__________________
69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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