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Thread: Need exhaust manifolds

  1. #1
    Registered Member Chevy Chase's Avatar
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    Need exhaust manifolds

    The 57 wagon exhaust is creating a tapping noise. Inspected the headers and the ox2 sensor wire is charred near the header tube. Also before the collector the header tubes have long flat spots from speed bumps? I'm guessing a header gasket has a burn hole. The 57 has 2" dropped spindles. The engine is a 350, alum heads with straight plugs, somewhat lumpy unknown cam, unknown headers, alum intake, and FI Tech fuel injection.

    The plan is to install Sanderson ceramic coated cast iron exhaust manifolds for more ground clearance. Do not want headers. It looks like the Sanderson manifolds will come too close to the spark plug wires tho. See photo. I kinda like the looks of them but will early Corvette-style 2-1/2" ram horn manifolds be less troublesome? Hoping to here from someone who has first hand knowledge with cast exhaust manifolds. Price is not an issue. Thanks, Chevy Chase-Sanderson-Headers-QP1000 (2).jpg

  2. #2
    Registered Member BamaNomad's Avatar
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    I've never used Sanderson's, but they certainly 'look' better than stock cast iron. I like the 2.5" rams horn manifolds for a mild performance engine; you can buy reproduction versions for a great price at Speedway and perhaps other sellers. They were used in mis-60's Corvettes; the corvettes used heat shields behind the manifolds and routed the spark plug wires behind and up from the rear of the engine to the distributor...

  3. #3
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    Quote Originally Posted by BamaNomad View Post
    I've never used Sanderson's, but they certainly 'look' better than stock cast iron. I like the 2.5" rams horn manifolds for a mild performance engine; you can buy reproduction versions for a great price at Speedway and perhaps other sellers. They were used in mis-60's Corvettes; the corvettes used heat shields behind the manifolds and routed the spark plug wires behind and up from the rear of the engine to the distributor...
    Good plan.

  4. #4
    Registered Member enigma57's Avatar
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    I bought a couple sets of Sanderson QP1000 cast-iron manifolds some years back for a 427 small block stroker. Plans changed and I sold one set. Still have the other set here. I special ordered them (passenger side manifolds for both sides) as I wanted both to drop at the center.

    Very good quality castings. And heavy. Should last a lifetime.

    Are you running stock '55 - '57 front engine mounts? Or the wider stance Hurst cradle type crossmember with '32 - '48 flathead mounts at the ends?

    The Sandersons I have (because they are both passenger side castings) can fit very close to the '58 and later side engine mounts (depends on heads, not all are the same). So if running '58 and later side engine mounts, with the one side, you could run machined spacers similar to the ones used with large tube Stahl headers.

    Anyway, I am sure you will like the Sandersons. Very high quality castings.......



    https://www.sandersonheaders.com/san...eader-set.html

    Happy Motoring,

    Harry

    P.S. >>> The Sanderson manifolds use a 3-bolt pattern with flat flange where the pipe attaches (not machined for donut gasket). So definitely consider copper flange gaskets...... These may fit...... Measure bolt spacing of 2-1/2" copper gasket and flange to make sure......



    https://www.sandersonheaders.com/san...?category_id=8
    Last edited by enigma57; 07-16-2020 at 03:48 PM. Reason: add link
    'G-d Bless The U.S.A.'...... Lee Greenwood......

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  5. #5
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    i have "hedman`s" on my small block, they too, have`nt much clearance for the spark plug boot. only ones that actually clear good are "accell`s SUPER STOCK" wires, and come in all colors.

  6. #6
    Registered Member Chevy Chase's Avatar
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    Thanks for the replies. Printed a list from Wilcoxcorvette.com of all the rams horn exhaust manifolds casting numbers from 1963 to 1972. Went on eBay and CL to get an idea of what they all look like. Conclusion: OEM GM exh manifolds are ugly. The jury is still out on the Sanderson cast exhaust manifolds because it seems they will create heat issues for the GM HEI spark plug wires. Therefore it looks like Summit Racing's Smoothie ceramic coated 2.5" outlet #G-9200S are a good solution. See photo. Can't complain about the price either at $200.99. Summit reducers recommended are # G4755 3 bolt, 2.5" reducer to 2.0", only $22.99. Also, free shipping.

    Harry: I like the idea of using copper gaskets for the collector. The copper material probably makes them reusable and of course no burn through.emoji mask (2).pngsum-g9200_sr_xl.jpg

  7. #7
    Registered Member WagonCrazy's Avatar
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    I second the recommendation on using copper gaskets. I use them and have not had leak issues.
    1957 Nomad- LS1/T56 on C4 chassis
    1959 Fleetside Apache 1/2 ton, shortbed, big window, 327ci.

  8. #8
    Registered Member enigma57's Avatar
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    Which ever way you go with your choice of exhaust manifolds, I am sure you will like the copper gaskets wherever you have a flat gasket surface to seal, Chevy Chase.

    If you go with the ramshorn manifolds, they will take a donut gasket, though. If I may ask, why would you go with the 2-1/2" outlet ramshorns and reduce head pipe sizing to 2"?

    When I built my 1st '55 Chevy many years ago, I initially ran '55 - '56 manifolds port matched to the 461 heads on my 327 and 2" duals. These manifolds are terribly restrictive. So when I could afford to, I bought a set of 2" ramshorn manifolds and ran them along with new head pipes and the same 2" duals. The engine sounded and ran noticeably better. Eventually, I scored a set of the 2-1/2" ramshorns and had a new 2-1/2" dual exhaust system with turbo mufflers made for it (this would have been around 1971 or early 1972). Again, the increase in power was noticeable over the previous 2" system.

    Dug out my exhaust sizing chart just now. Its for full length muffled systems. Not perfect, I'm sure but a good go-by......



    2.0" duals will support a max 200 HP
    2-1/4" duals will support a max 250 HP
    2-1/2" duals will support a max 400 HP

    My Note: Personally, I would think 2-1/2" duals would support more like 350 HP.

    Of course, you can run a higher horsepower engine through smaller pipes than this, but the exhaust will begin robbing power at higher RPMs as backpressure builds and begins to work against you.

    A good compromise for a mild to moderately warmed over 350 engine in a road car running 2-1/2" ramshorn or Sanderson manifolds might be a 2-1/2" dual system back to some good flowing 2-1/2" Walker DynoMax Super Turbo mufflers (largest and longest oval case you can fit in space available) and run 2-1/4" tail pipes. And a good H-type crossover (balance) pipe same size as head pipes, of course.

    Happy Motoring,

    Harry
    'G-d Bless The U.S.A.'...... Lee Greenwood......

    http://www.youtube.com/watch?v=U_5aoptI5j0

    Staff Sergeant Roy Benavidez......

    https://www.youtube.com/watch?v=i3nncd4sxaM&t=466s

  9. #9
    Registered Member Chevy Chase's Avatar
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    unnamed (1).jpgHarry, Good information. I thought about the exhaust diameter measurement I posted. The measurement was 2" diameter for the tail pipes. Today measured the header pipe diameter in front of the muffler and it is exactly 2.25" diameter, which depending some variables will support 250 hp or a wee more. Attached is another hp chart based on exh dia. When you compare exh dia to hp ratings posted by GM, Gm is far more generous with hp ratings. May be a matter of gross hp compared to net hp.

    Looks like I'll be installing 2.5" diameter head pipes and mufflers that are 2.5" in and 2.25" out. I don't believe tail pipe diameter is as critical.

    Had a little bit of memory lapse on the doughnut gaskets for the cast iron manifolds. Summit Racing sells SCE copper gaskets with reinforced bolt holes for the exh manifold to cylinder head part #SCE #4311. I plan to go with them. Cheersemoji mask (2).png
    Last edited by Chevy Chase; 07-18-2020 at 11:50 AM. Reason: forgot chart

  10. #10
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    look into "remflex", i swear by them.

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