1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

1973 Blazer SBC 350 - Need thoughts on exhaust system

Discussion in 'Engine & Performance' started by Kyle K, May 7, 2020.

  1. Kyle K

    Kyle K Junior Member

    Posts:
    8
    Likes Received:
    7
    Joined:
    Feb 14, 2020
    Location:
    Charlotte, NC
    First Name:
    Kyle
    Truck Year:
    1973
    Truck Model:
    Chevy Blazer K5
    Engine Size:
    350
    Hey folks, hoping you can help me out with some exhaust questions for a 1973 Chevy Blazer. I just purchased a new SBC 350 and plan on putting new headers and exhaust on it (https://www.jegs.com/i/Chevrolet-Performance/809/12681429/10002/-1).

    Current exhausted is pretty rusted, and if I’m putting in a new motor I feel like changing out headers too. Current exhaust is 2”. I’m not as concerned about tons of horsepower, as the motor is basic anyway, but do want a nice hearty sound to it. Not trying to wake up neighbors, but want people to look at it and say “man, that sounds like a nice ‘70s truck”. Of course want it to be responsive as well.

    So my questions….
    1. What size pipe should I go up to? If I’m at 2” now, does 2.25 or 2.5” make that big of a difference? Most systems out there on Summit are 2.25”. My buddy actually as 3” racing headers, but would have to build it all out and read that it’s really too big for that small HP of a motor
    2. If the result is 2.5” as the way to go, looks like I’ll have to build that out. Don’t have that type of bending equipment, so would piece/clamp together. Is it worth it? Or should I go with one of these already complete systems (note they’re 2.25”)…https://www.summitracing.com/parts/hok-16523hkr/year/1973/make/chevrolet/model/blazer
    3. I’m thinking glass packs vs a turbo muffler. Thoughts on how well this would sound with the rest mentioned above?
    Thanks!
     
    Catbox likes this.
  2. 75gmck25

    75gmck25 Full Access Member

    Posts:
    877
    Likes Received:
    509
    Joined:
    Oct 13, 2016
    Location:
    VA
    First Name:
    Bruce
    Truck Year:
    1975
    Truck Model:
    K25 Camper Special TH350 NP203
    Engine Size:
    5.7
    For that 350 crate a 2 1/4” exhaust will be fine for the flow you need. Nobody makes an off-the-shelf 2 1/2” exhaust for the 4WD squarebody, and making up your own would take you quite a bit of time. I don’t think it’s worth it unless you just have time on your hands.

    My suggestion is to use full length headers, preferably with 3/8” flanges and 16 gauge tubing ( to hold up better), and 2 1/4” exhaust with a balance pipe. Muffler choice will depend on your preferences. There are lots of muffler tests and shootouts to read through online. To keep noise down in the truck, run the pipes out to exit past the bumper.

    I think I’m going to use Dynomax superturbos, but I’m also looking at Magnaflows or Dynomax Ultraflow (both are a more straight through design). The Borla seems to be out of my price range, and I don’t like the tone of most Flowmasters. I am looking for a low pitch muscle car tone without excessive noise at low speeds or drone at cruise). Everyone has their own preferences.

    Bruce
     
  3. 84 M1008

    84 M1008 Full Access Member

    Posts:
    337
    Likes Received:
    171
    Joined:
    May 11, 2018
    Location:
    New York
    First Name:
    Wayne
    Truck Year:
    1984
    Truck Model:
    M1008 K30
    Engine Size:
    6.2 diesel
    Magnaflows sound nice, I had them on my 97 Z71.
     
  4. Catbox

    Catbox Full Access Member

    Posts:
    698
    Likes Received:
    1,367
    Joined:
    Jul 12, 2018
    Location:
    Portland Oregon
    First Name:
    Peter
    Truck Year:
    1979
    Truck Model:
    C20 Silverado Camper Special
    Engine Size:
    461
    If it were my truck, I would put the 2-1/2 inch exhaust all the way back.
    That way, if you choose down the road to add more pep to the engine your exhaust will handle it just fine.

    My truck came with 2-1/2 inch main pipes from the manifolds to the mufflers.
    From there they were 2-1/4 inch.
    This is on a stock-ish 454 and it was choked off.

    When I redo it this time with new headers, I will be putting a 3 inch system under it.
    It will be oversized for what I have now, but when I put new stuff on the engine it will be just fine.
     
  5. 75gmck25

    75gmck25 Full Access Member

    Posts:
    877
    Likes Received:
    509
    Joined:
    Oct 13, 2016
    Location:
    VA
    First Name:
    Bruce
    Truck Year:
    1975
    Truck Model:
    K25 Camper Special TH350 NP203
    Engine Size:
    5.7
    Catbox - one difference for you is that you have a 2WD. There are off the shelf systems available (Pypes, IIRC) for 2WD, and for a custom system you don’t have to work around a transfer case cross member that was designed for single exhaust.

    All the stock systems from Summit and Jegs for 4WD are 2 1/4”, so you have to decide how much you want to spend for a custom made 2 1/2” system. And you have to find a local shop that is able to make it. It can be done, but it gets complicated. I don’t think a 2 1/4” exhaust with headers and low restriction mufflers is going strangle an SBC unless you are planning for 400 HP and up.

    Bruce
     
    Catbox and Octane like this.
  6. Octane

    Octane Full Access Member

    Posts:
    158
    Likes Received:
    144
    Joined:
    Dec 31, 2019
    Location:
    Atlanta
    First Name:
    Eddie
    Truck Year:
    1977
    Truck Model:
    K10
    Engine Size:
    350
    For the record I have stock exhaust manifolds and for the ease of bending pipe we ran 2" pipe down to the turn point,maybe a foot or so.Then ran 2.5" all way back to rear. (77 chevy k10 with flowmasters and duals). Because personally I hate headers...lol
     
  7. 78C10BigTen

    78C10BigTen Full Access Member

    Posts:
    8,341
    Likes Received:
    6,688
    Joined:
    Apr 12, 2017
    Location:
    pennsylvannia
    First Name:
    Ted
    Truck Year:
    1978
    Truck Model:
    C10 BIG TEN
    Engine Size:
    350
    Im in the 2wd camp here but i threw on second hand long tube headers with a set of 3" collector adapters and true dual 3" all the way to just before the rear with turn outs and my flowmasters someplace in between. Is it loud and obnoxious.... yes, its it too big for my wimpy stock 350...yes but thats how i wanted it and like the sound. Sorry just wanted to pop my 2 cents in

    2019-05-08 22.13.07.jpg

    20190131_152629.jpg
     
    Catbox, Octane, bucket and 1 other person like this.
  8. Frankenchevy

    Frankenchevy Supporting Member Supporting Member

    Posts:
    3,723
    Likes Received:
    3,316
    Joined:
    Jan 3, 2018
    Location:
    USA
    First Name:
    Guy
    Truck Year:
    Square
    Truck Model:
    CUCV
    Engine Size:
    Small
    My long tubes terminate at an elevation where 4-5’ of straight pipe shoots above the crossmember and to either side of the transfer case. I had to rework my trans shift linkage. Once you’re past the cab you can transition up and over the rear axle with back to back 45s, then into a muffler. That’s what I did.

    45s can be had from any local auto parts store, or mandrel can be found online.
     
    Catbox likes this.
  9. skysurfer

    skysurfer Full Access Member

    Posts:
    2,243
    Likes Received:
    711
    Joined:
    Oct 23, 2010
    Location:
    west coast
    First Name:
    John
    Truck Year:
    1989 Suburban
    Truck Model:
    V2500
    Engine Size:
    5.7/TH400/NP241C
    Choose your mufflers carefully. People here will tell you their MegaTurboHowler3000 muffler on their truck sounds awesome, and then you'll find that it's way too loud for a K5 where you're practically sitting on top of it. A mellow throaty exhaust sounds fine, but an obnoxiously loud one is just tiresome.
     
    Catbox likes this.
  10. bucket

    bucket Super Moderator Staff Member

    Age:
    38
    Posts:
    21,267
    Likes Received:
    6,726
    Joined:
    Aug 3, 2010
    Location:
    Usually not in Ohio
    First Name:
    Andy
    Truck Year:
    '77, '78, '79, '84, '88
    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    Loud pipes save lives!
     
    Catbox, Customblue and 78C10BigTen like this.
  11. skysurfer

    skysurfer Full Access Member

    Posts:
    2,243
    Likes Received:
    711
    Joined:
    Oct 23, 2010
    Location:
    west coast
    First Name:
    John
    Truck Year:
    1989 Suburban
    Truck Model:
    V2500
    Engine Size:
    5.7/TH400/NP241C
    Pfft, you sound like one of those leather-wrapped clowns on their Hardly Makeitsons. You’re better than that bucket.
     
    clendon1 likes this.
  12. idahovette

    idahovette Full Access Member

    Age:
    71
    Posts:
    1,878
    Likes Received:
    2,165
    Joined:
    Aug 7, 2016
    Location:
    Weiser Idaho
    First Name:
    Perry
    Truck Year:
    1975-1979
    Truck Model:
    K20-K10
    Engine Size:
    350
    There's a LOT of difference between a loud bike and a throaty Square!!!!
     
    bucket and RecklessWOT like this.
  13. RecklessWOT

    RecklessWOT Full Access Member

    Age:
    31
    Posts:
    506
    Likes Received:
    683
    Joined:
    Feb 20, 2015
    Location:
    New Hampshire
    First Name:
    Kevin
    Truck Year:
    1987
    Truck Model:
    V10 Suburban Silverado
    Engine Size:
    350 TBI
    To each their own, I'm not one to knock another man's personal preference. But out of curiosity, what don't you like about headers? The way they look or something? I understand someone liking flowmasters over glasspacks or 2.5" over 3" etc, but I can't figure what's not to like about headers? As I said, not trying to start something, really just want to hear what you don't like about them, maybe there's something I never thought of (besides maybe not being smog compliant, but fuck all that lol).

    Also, for the record I don't have headers on my truck so I'm not trying to defend them or anything. Hah I didn't want to waste the money when I have so many more important things to work on first, but I definitely plan to get some when I build the new engine
     
    Catbox, Octane and 78C10BigTen like this.
  14. Rusty Nail

    Rusty Nail Whatever!

    Posts:
    5,567
    Likes Received:
    3,298
    Joined:
    Jan 29, 2015
    Location:
    MAGA Country
    First Name:
    Rusty
    Truck Year:
    1977,1988
    Truck Model:
    C20, K5
    Engine Size:
    350, 350
    I bought small headers and 2.25 pipe for my 88 Blazer with normal engine.
    Flowmaster 40s were already there and sound awesome with an H pipe...it doesn't pop even with two mufflers. Super rad!

    I also run one 2.25" Dynomax Super Turbo in a different truck .

    Whatever ya do, connect both sides...:pedobear:

    20190326_151304.jpg
     
    hoagster, Catbox and 78C10BigTen like this.
  15. bucket

    bucket Super Moderator Staff Member

    Age:
    38
    Posts:
    21,267
    Likes Received:
    6,726
    Joined:
    Aug 3, 2010
    Location:
    Usually not in Ohio
    First Name:
    Andy
    Truck Year:
    '77, '78, '79, '84, '88
    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    Ha! I disagree... I'm not better than that :rofl:
     
    Rusty Nail and Catbox like this.

Share This Page