CK5
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Header primary sizes.

What is better for a mostly stock 350. 1.5'' or 1.625''.

Going to be building my own headers for my project.
What mods are done to the mostly stock 350....does it have typical done @ 4500 rpm stock heads? I would use 1.5 I.D. tubes, and get 16 ga. if you can, with 38" long primary tubes, and as long as feasible 3" collectors for torque help. If it can't rpm, it might as well be a torque maker.
And don't worry about trying to get equal length pipes either.
 
As of now it only has a 305. Plans are to swap a new L31 crate motor in. Will have stock heads and cam with roller rockers. Running a TPI setup. The intake limiteds me to about 5k. Rev limtiter in the ECM is set at like 5500.

Look in my sig for my build.
 
was also thinking about a torque step design. Come out with 1.5 then switch to 1.625 for the bottom half.

here is my design with just 1.5 primarys.

header.jpg
 
That's great except they won't clear your motor mounts or the frame either probably. To be honest, I don't think you'll be able to tell the difference either way. Just get a set of long tubes (I like hooker comps) and run 'em. Headers are cheap enough for these trucks, that unless you have a 555 big block and need huge tubes, it's not worth making your own.

The thing you will tell a difference is you don't want thin, unwelded, leaky flanges.
 
That's great except they won't clear your motor mounts or the frame either probably. To be honest, I don't think you'll be able to tell the difference either way. Just get a set of long tubes (I like hooker comps) and run 'em. Headers are cheap enough for these trucks, that unless you have a 555 big block and need huge tubes, it's not worth making your own.

The thing you will tell a difference is you don't want thin, unwelded, leaky flanges.

I no longer have the stock crossmember or motor mounts. Made my own. The design i have will clear. Also my steering shaft runs off to the side and not straight like stock.
 
Stock to average power build 1-5/8ths long tubes.

Serious power 1-3/4s.

I would never use 1 1/2 primarys.

i agree.... lower rpm torque monster, 1 5/8..... screamer, 1 3/4......


i've never seen/noticed sb headers with less than 1 5/8.....
 
What mods are done to the mostly stock 350....does it have typical done @ 4500 rpm stock heads? I would use 1.5 I.D. tubes, and get 16 ga. if you can, with 38" long primary tubes, and as long as feasible 3" collectors for torque help. If it can't rpm, it might as well be a torque maker.
And don't worry about trying to get equal length pipes either.

Aren't headers measured by I.D. ?
1.5" I.D. would be 1.625 O.D. for a 16 ga. tube.

i agree.... lower rpm torque monster, 1 5/8..... screamer, 1 3/4......


i've never seen/noticed sb headers with less than 1 5/8.....

Flowtech headers come in 1.5"
 
mmm K, so I guess the 1-5/8 O.D. would be the ones I'd choose too

Something to think about....Hooker side mounts for my Vette are only available in 1-7/8, pretty big I think, but I had to have em.
 
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