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> OMG! Carb manifolds are crap..., Straight out of the box
McMark
post Feb 24 2010, 06:33 PM
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No real surprise here. The manifolds for carbs are pretty crappy. I just spent WAY TOO LONG truing up a set with sandpaper on glass. I snapped a couple of pics to show just how not flat these things are. I would expect a huge vacuum leak if I had left these guys alone.

The area in the circle shows what hasn't been touched yet by the sandpaper. This is after a LOT of sanding. And it took a LOT more to get it completely out. This is a cheap, and relatively quick project that any carb owner can do with the engine in the car. All you need is a piece of thick glass, which most any house glass shop should be able to cut for you and round the edges, for cheap. Some sandpaper and tape and a sure, steady hand. Hold the manifolds flat against the glass and use long, even, slow strokes. You can also use a sharpie to check your work as you get closer to finishing. Draw on the surface, take a couple strokes, then see how much sharpie has been removed.


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Gint
post Feb 24 2010, 06:36 PM
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BTDT Most of those cheap manifold bases for Weber carbs are crap out of the box.
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hwgunner
post Feb 24 2010, 06:38 PM
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That sucks. I will have to pay attention to mine when i put them on.
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McMark
post Feb 24 2010, 06:40 PM
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Best I can guess, is that the surfaces are machined at the factory while the metal is still REALLY hot and distorts when it cools.
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Mike Bellis
post Feb 24 2010, 06:42 PM
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Just TIG weld them to the head. They will seal great! (IMG:style_emoticons/default/welder.gif) (IMG:style_emoticons/default/poke.gif)
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URY914
post Feb 24 2010, 08:22 PM
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I fitted a steel spacer to pull the base down to the head so it will seal. Have a look...

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Ferg
post Feb 24 2010, 08:34 PM
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QUOTE(URY914 @ Feb 24 2010, 07:22 PM) *

I fitted a steel spacer to pull the base down to the head so it will seal. Have a look...

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That spacer looks heavy (IMG:style_emoticons/default/bye1.gif)
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SirAndy
post Feb 24 2010, 08:34 PM
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Another reason to use the thick FI spacers with the carb manifolds ...

(IMG:style_emoticons/default/shades.gif) Andy
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McMark
post Feb 24 2010, 08:39 PM
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Just cause they're thick doesn't mean they seal better. Most of the thickness of the thick FI seal is plastic that doesn't really deform, so essentially it's just like a paper gasket. But the FI gaskets do keep heat out of the carbs, and I use them on carb installs. I only mean to point out that you can't expect the FI seal to solve this particular problem, cause it won't.
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shaggy
post Feb 24 2010, 09:19 PM
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you could have someone build tig on them then have them milled. kinda a lot of work for 914 carb manifolds though...

-jim
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URY914
post Feb 24 2010, 09:46 PM
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Yes, the hard thick FI spacers are not meant as a seal. If you want a real seal you'll need to machine a grove and O-ring them.
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Eric_Shea
post Feb 24 2010, 10:14 PM
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1350 lbs. 4 oz. Bummer... (IMG:style_emoticons/default/sad.gif)
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URY914
post Feb 24 2010, 10:18 PM
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QUOTE(Eric_Shea @ Feb 24 2010, 09:14 PM) *

1350 lbs. 4 oz. Bummer... (IMG:style_emoticons/default/sad.gif)


Nope. It did it on my street car not the race car, (IMG:style_emoticons/default/shades.gif)
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burton73
post Feb 24 2010, 10:19 PM
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QUOTE(McMark @ Feb 24 2010, 04:33 PM) *

No real surprise here. The manifolds for carbs are pretty crappy. I just spent WAY TOO LONG truing up a set with sandpaper on glass. I snapped a couple of pics to show just how not flat these things are. I would expect a huge vacuum leak if I had left these guys alone.

The area in the circle shows what hasn't been touched yet by the sandpaper. This is after a LOT of sanding. And it took a LOT more to get it completely out. This is a cheap, and relatively quick project that any carb owner can do with the engine in the car. All you need is a piece of thick glass, which most any house glass shop should be able to cut for you and round the edges, for cheap. Some sandpaper and tape and a sure, steady hand. Hold the manifolds flat against the glass and use long, even, slow strokes. You can also use a sharpie to check your work as you get closer to finishing. Draw on the surface, take a couple strokes, then see how much sharpie has been removed.


Silicone Carbide I take it but what grit?

Bob
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Eric_Shea
post Feb 24 2010, 10:20 PM
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Nope. It did it on my street car not the race car,


(IMG:style_emoticons/default/lol3.gif)
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Mark Henry
post Feb 24 2010, 10:39 PM
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If you think it's bad on that end don't look at the other end and the nice smooth transition from the carb bores (IMG:style_emoticons/default/poke.gif)
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yeahmag
post Feb 24 2010, 11:35 PM
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I'm still a fan of nice, thick, fiber style carb gaskets...
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lotus_65
post Feb 25 2010, 04:02 AM
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good even contact should aid in heat sinking too...

another thing i see with my manifolds is the mold edges in the bore. should i ream/clearance them smooth?
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VaccaRabite
post Feb 25 2010, 07:54 AM
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I had to glass sand mine too. A lot. In order to get them to true up.
I thought that was all just part of the game? One look at the ones that I had, and there was no way they were sealing as is, w/o some sort of filling sealer, unless I smoothed them.

I used 320 grit sticky backed sand paper over window pane glass. Worked like a charm.

Zach
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TheCabinetmaker
post Feb 25 2010, 08:11 AM
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Looks like someone been beating on your framing square. I've got two of those!!!!!!!
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