1973 Blazer SBC 350 - Need thoughts on exhaust system

[Kyle K]

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!

 

[75gmck25]

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

 

[84 M1008]

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

Magnaflows sound nice, I had them on my 97 Z71.

 

[Catbox]

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.

 

[75gmck25]

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

 

[Octane]

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

 

[78C10BigTen]

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

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[Frankenchevy]

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.

 

[skysurfer]

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.

 

[bucket]

Loud pipes save lives!

 

[skysurfer]

Loud pipes save lives!

Pfft, you sound like one of those leather-wrapped clowns on their Hardly Makeitsons. You’re better than that bucket.

 

[idahovette]

There's a LOT of difference between a loud bike and a throaty Square!!!!

 

[RecklessWOT]

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

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 **** 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

 

[Rusty Nail]

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...

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[bucket]

Pfft, you sound like one of those leather-wrapped clowns on their Hardly Makeitsons. You’re better than that bucket.

Ha! I disagree... I'm not better than that