HP Exhaust Manifolds???

Discussion in 'Small Block Tech' started by Paul Stewart, Jul 10, 2017.

  1. Paul Stewart

    Paul Stewart Well-Known Member

    Are there any stock options for HP exhaust manifolds on a 350?

    I read something about a 2.5" manifold on larger cars with the 350?????

    Thank you!
     
  2. alec296

    alec296 i need another buick

    Interesting thought but never heard that. Some cars have a heat riser on the left side and no ball flange. So opening may be bigger but you need an exhaust donut then. TA performance has 2.5 downpipes for 350 with 2 inch ball flange it's barely any length before the welded 2.5 pipe.
     
  3. Mark Demko

    Mark Demko Well-Known Member

    All 350's used essentially the same manifold, no Hi-Perf iron manifolds were made by Buick.
     
    MrSony likes this.
  4. MrSony

    MrSony Well-Known Member

    All 350s used the same manifolds. Some of the earlier ones had this weird indentation on the driver's side that was less intrusive on later motors (may have been car specific as well) but as far as flow they are all essentially the same. That's why I like the 350, no year is really better than any other. I do like the 75-80 motors as they have the stronger rods, but other than that... nadda.
     
  5. Paul Stewart

    Paul Stewart Well-Known Member

    What size is the collector on a stock unit?
     
  6. MrSony

    MrSony Well-Known Member

    About 2 to 2.25 inches. You can hog em out if you want too, but I don't think there is enough meat to get that extra 1/4 to 1/2
     
  7. alec296

    alec296 i need another buick

    It's a 2 inch ball flange. You might not seal with 2.25. An x or h balance tube might help some power. What is the rest of your engine /trans/rear gear setup like. Maybe there's other tweaks that can up you Power .
     
  8. Paul Stewart

    Paul Stewart Well-Known Member

    350 high compression, TH350 3.08 open rear. I plan on 3.42 or 3.64 rear, TA performance intake, cam and maybe Stage 1 heads. 2 1/2 Exhaust with or without headers? I would like to keep it as stock appearing as possible. Pertronix ignitor or HEI?
     
  9. MrSony

    MrSony Well-Known Member

    Headers are not really necessary, the stock manifolds actually flow pretty well. You can gasket match the manifolds and exhaust side of the heads if you like, as well as smoothing out any bumps or ribs in the manifolds you can get to. If you go HEI there may be fitment issues, both of the distributors side by side the HEI is MASSIVE compared to points. If you're looking for stock, go with the points eliminator kit. That along with a decent dual exhaust (h pipe balance tube as well), looser 2200sih stall converter, TA 284 cam, lifters, and springs, an the other stuff you mentioned will get you at least in the high 300s maybe even 4 if you use headers. They are a guaranteed 30hp.
     
  10. alec296

    alec296 i need another buick

    a pertronix or hei would not fit under a gs ram air cleaner if you have one. But the pertronix has better adjustability for timing curve.. the 284 cam is decent . I like the crower level 3 . They are similar. compression is closer to 9.2-9.4 then the advertised 10.2. . A Quadrajet Power built carb or by everyday performance. Other points mentioned,convertor, conversion kit and recurve distributer. With headers maybe 350. These engines are closer to 240-250 stock. There are not really any stage 1 350 heads, but you can get larger valves like the stage 1 and better valve springs. Oil modifications to block are needed for the extended rpm range of any cam put in. I would suggest replacing front cam bearing also. They wear and cause low oil pressure problems. The hi volume oil pump kit is not worth it nor is it needed .
     
  11. Paul Stewart

    Paul Stewart Well-Known Member

    Good info guys, thank you. I will start with the intake and 284 cam. Pertronix ignitor II internal kit, converter, gears and then see how to make it breathe better? 2 1/2 " exhaust, and is head work really worth it or settle for headers instead?
     
  12. sean Buick 76

    sean Buick 76 Buick Nut

    Head work is where the real HP gains are at... The only really strong running 350s have either boost or nitrous or head porting....
     
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  13. MrSony

    MrSony Well-Known Member

    Agree with sean. until the AL heads come out, spend the extra dough to have your heads worked on by TA or a well known Buick guru in your area. An engine is just a glorified air pump after all. More air in and out, more power. At the very least I recommend a good valve job.
     
  14. alec296

    alec296 i need another buick

    Except the pure stock guys . Run 12s with stock heads and and a 212 cam.
     
    Gary Farmer likes this.
  15. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    To be fair, running 12's on an all iron engine requires some not-so-street-friendly mods (4 series gearing and suspension tricks, along with super sticky traction), as well as the use of race fuel with crazy high compression.
    Otherwise, getting a mid 13 car out of an all iron, pump gas friendly Buick 350 engine isn't unrealistic.
     
  16. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    If your goal is power and don't care how it's obtained, your dollars are better spent on headers. Just be aware of the tradeoffs vs manifolds.
    Make sure your compression matches your cam and head flow, or at least fairly well. Don't go too high on compression if you want the freedom of pump gas. It's better to have compression on the safe side than borderline detonating on premium pump gas. You'll more than make up for any power loss with better flowing heads mated to headers and the gearing to take advantage of it.

    The Crower level 3 or TA 212-350 cams are about as big as you want to go using exhaust manifolds. Larger cams with tighter specs and less exhaust emphasis will benefit more from better flowing heads and headers.

    There are exceptions to any 'rule', but this is the 'easy' answer.
     
    Last edited: Jul 12, 2017
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  17. 8ad-f85

    8ad-f85 Well-Known Member

    You don't really need a buick expert to do mild porting. The bang for the buck starts from the valve seat and bowl.
     
    Gary Farmer likes this.
  18. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    ...and you don't even need to be a head porting master with 200 years of experience doing it, either. A good understanding of and experience with metal contouring, basic understanding of aerodynamics (sharp/rough edges and turns harm laminar flow), and you don't even need a flow bench or other fancy, specialized equipment as long as you use the factory casting as the template and don't venture outside of that.
    That's been my experience anyway. Good gains can be had with some elbow grease and some patience.
    Lots of guys have gone down this path with very good results.
    You're not really changing the behavioral personality of the heads so much as you are simply improving what's already there.
     
  19. 8ad-f85

    8ad-f85 Well-Known Member

    Actually, you ARE changing the behavioral personality of the heads, the way the cam events help it breathe, the engine's manners, etc...
     
    Gary Farmer likes this.
  20. sean Buick 76

    sean Buick 76 Buick Nut

    Since we are are so close to having the alum heads available I would. Advise people to not even touch the iron heads and swap to alum once they are ready ... And match a custom can with the heads at that time... I would shoot for 10:1 compression for a naturally aspirated build and 9:1 for a boosted engine.
     

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