300/340 Headers question.

Discussion in 'Small Block Tech' started by 72Custom350, Nov 21, 2021.

  1. 72Custom350

    72Custom350 Active Member

    I was wondering who has installed headers on their 66-67 300's or 340's? I'm toying with the idea on my 67 Special. Are they worth the 370+ dollars for them. I seem to only be able to find the Sanderson shorty headers.
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Probably depends on the rest of your combination. For a completely stock engine, I would guess not.
     
  3. 72Custom350

    72Custom350 Active Member

    The 300 is getting a 65 4bbl intake and a PerTronix distributor, it already has true dual exhaust. Ive heard the factory exhaust manifolds flow pretty good, and honestly its only 300 cubes that wont see north of 5,000 rpm.
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    So unless you want the cool factor and like the added exhaust noise, probably not.
     
  5. 72Custom350

    72Custom350 Active Member

    Right on, thanks for that!
     
  6. philbquick

    philbquick Founders Club Member

    A Pertronix ignitor III, flame thrower coil and a curve kit will give you the most gain for the least money. Make sure your timing chain is in good condition. I'm here too!
     
  7. 72Custom350

    72Custom350 Active Member

    I am planning on doing a Pertronix III distributor and and a flame thrower II coil. Im excited to see the gains, hoping to crack 175 at the wheels with just the intake and ignition.
     
  8. 1adam12

    1adam12 Well-Known Member

    I installed a set of postons on my 300 probably 15 years ago. I did and x pipe and 2.5 in pipes to turndowns in front of the axle. This made a noticeable diffrence. I did it all at the same time so I can only speak for the entire package. It replaced a crimped exhaust shop special. The postons will be hard to find now. I bought them from a board member here that never installed them. They fit great. I think all you can buy now are the shorties from Sanderson. I don't know if they would be worth it unless your are replacing cracked manifolds. I can tell you the land rover factory stainless manifolds fit beautiful on the passenger side but the driver side has clearance issues.
     
    mineseats9 and sean Buick 76 like this.
  9. gsjohnny1

    gsjohnny1 Well-Known Member

    i know of one guy i think that has long tube headers. done about 30 yrs ago
     
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  10. Jim Blackwood

    Jim Blackwood Well-Known Member

    I have 32" primary equal length (within 1/4" all 8 tubes) headers that I built 45 years ago and they make more difference than you might think. Ran them on everything from a mild 215 to a blown 350cid 340. 1-5/8 primaries and 2-3/8" collectors. They are good enough that I went to the trouble of stripping and re-coating them.

    Jim
     
    Dano likes this.
  11. 455monte

    455monte Well-Known Member

    I put the sanderson headers on my 340.
    Engine is stock compression with street strip cam and a 650 cfm carb.
    The headers made a considerable difference.
    Considering a stock manifold is 1.875 outlets the 2.5 collectors make a huge difference in area.
     
  12. 72Custom350

    72Custom350 Active Member

    Even with them just being shorties? I always heard the long tubes are better for all around power.
     
  13. sean Buick 76

    sean Buick 76 Buick Nut

    Yes long tube headers are superior in every way vs shortys for power and torque. Not many options though for the 300/340.
     
  14. 455monte

    455monte Well-Known Member

    Yes even with em being shorts it helped.
    Note that the sanderson 340 headers will not work with factory z bar linkage.
    I had to convert mine to a hydraulic clutch
     
  15. Jim Blackwood

    Jim Blackwood Well-Known Member

    The equal length primaries help quite a bit too. Off the shelf headers, even ones that claim equal length will vary by a couple inches or more. The shorty headers don't add much but they are a little better than the cast iron manifolds. There is no scavenging effect with the short headers, it takes 30" or so for a pulse to move down the tube before the next pulse so anything less cuts of scavenging.

    Back then, using a gas torch and pre-cut flanges, I spent 80 hours making my first set, but I had a lot of complex bends which were all made by cutting and welding with preformed tube. It could be done a lot faster. I've made 2-1/2 sets and would not shy away from the job if I needed to make another set. You can apply the ceramic coating yourself if you have a sandblaster. Ultimately the cost was similar to a purchased set but the result was exactly what I wanted.

    Jim
     
    sean Buick 76 likes this.
  16. sean Buick 76

    sean Buick 76 Buick Nut

    any pics?
     
  17. Jim Blackwood

    Jim Blackwood Well-Known Member

    Just for you Sean:

    IMG_0001.JPG

    IMG_0002.JPG
     
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  18. 72Custom350

    72Custom350 Active Member

    That's beautiful!
     
  19. Jim Blackwood

    Jim Blackwood Well-Known Member

    I also made a set of headers for a Jetfire Turbo engine and half of a set for an IH-392. With today's tools and such doing a set from scratch would be fairly easy. You can buy the flanges already cut and there are some nice clamps and layout tools available, and of course a small mig welder would do a fine job on the welds. I used a length of 1/16" welding rod to do the tube layouts. Lots of measuring and adding if you want true equal length, but they don't have to be perfect. Within 2" is generally considered quite good and you can extend the tube at different lengths into the collector if need be.

    On the 392 I sand packed and bent the tubes. That worked pretty well but as I was using heavy wall tubing I had to build a furnace to heat the bend area before bending. I did the first one because of a broken manifold and then never got around to the other side. Ended up selling it to a guy for an IH four cylinder when I parted out the truck.

    Jim
     
    sean Buick 76 likes this.
  20. sean Buick 76

    sean Buick 76 Buick Nut

    Thanks for the pics and info!
     

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