Carb body warping...

[Qikbbstang]

I just went by their shop and asked Eddie the head honcho at National Carb. about machining warped carb parts and he laughed saying the only time they machine is when there are pits. He did mention something about Holley castings from China at one time being terrible though.


http://www.nationalcarburetors.com/

[cjshaker]

The other side is carb gaskets are pretty thick the "out of true" pictured in this thread looks to be at most what three-four thousandths?............ Seems a gasket would just do the job of that clearance

Try about .020. Heat and leverage over a 20+ year period can warp anything. Even cast iron blocks. But I'm sure you already knew that.

I just went by their shop and asked Eddie the head honcho at National Carb. about machining warped carb parts and he laughed saying the only time they machine is when there are pits.

Try talking to people who build and tune engines.

[My427stang]

I just went by their shop and asked Eddie the head honcho at National Carb. about machining warped carb parts and he laughed saying the only time they machine is when there are pits. He did mention something about Holley castings from China at one time being terrible though.


http://www.nationalcarburetors.com/

Well, don't just think of it as crooked, think of it as a bathtub.  The corners pull up and the center hangs which doesn't allow any compression of the center of the gasket.

They run fine crooked for a short time, but it doesn't take long for the gasket to relax and then you have cross channeling problems.

I respect that you went to ask an expert, but what other surface would you allow to be .010 or greater crooked and still run it?...and this is over a very short distance. 

[Qikbbstang]

I sure see your points of view. Just scratch my head thinking about the thousands of rebuilt  carbs Nat Carb does -- do some large percentage all run like crap when the gaskets take a set?...Hard to believe Nat Carb offers "Lifetime"  guarantee's on all carbs and personally wonder how many they get back.

[My427stang]

Well I can say this, if you use the old Holley brown gaskets, the shellac that we all hate so much when we go to clean it, seems to hold them together better than the blue gaskets.  It's just impossible to do a real time repair or jet change LOL

It could be he uses something other than non-stick gaskets, but honestly, I think it's more than likely just a numbers game.  Sell enough and the comebacks don't matter, or people blame something else if it doesn't run right

[66FAIRLANE]

I use a little 2 inch 3 prong face cutter too when I have to. Have used it on warped base plates too.

[cjshaker]

Well I can say this, if you use the old Holley brown gaskets, the shellac that we all hate so much when we go to clean it, seems to hold them together better than the blue gaskets.  It's just impossible to do a real time repair or jet change LOL

Ain't that the truth!! Unfortunately I hadn't learned that 23 years ago when I built my truck engine. I spent more time scraping those old gaskets than I had in the entire rebuild.   Now I replace them before I even put them on.

[Barry_R]

Holley carbs were traditionally cast from zinc.  Makes really nice, dense castings with minimal porosity, but they are also very soft and temperature sensitive.  Holley was very much aware of such issues all the way back into at least the 1970s.  Some of the industrial/commercial vehicle applications used captive springs under the float attaching screws to limit the amount of torque and tension seen by the main body.

They were essentially forced to transition from soft cork gaskets into the various (black & brown) paper and resin/glue variations in response to 1980s changes in fuel chemistry and evaporative emissions laws.  The paper gaskets are less compressable and impart greater loads into the main threads.  Couple that with the use of nylon bowl screw gaskets and hex head fasteners (as opposed to the original soft paper and straight blade) and you get a lot more opportunity for overtightening & distortion.  If you look at an HP casting you'll see that they've added ribs to the casting to reduce the bending tendency.

[Qikbbstang]

Ah WTF I noticed Nat Carb has three "Test Motors" 4, 6 & 8cyl.. The 8cyl I caught them replacing on a Sat while on a bike ride. A brand new GM 350 4-bolt longblock they bought delivered for under $1500.
    Hate to say it but Nat Carb does not load any of the motors while running them. Nothing even remotely resembling a "pump". There's no way to put a load on them. Obviously the motors are missing pulling the motor against a load while on the carb. When the driver stomps if goes fat, lean or just right it's up to the gods.
      What's good for the goose is good for the gander. How about the Metering Blocks don't they warp and distort like the carb bodies and aren't the deviations in "trueness" of the gasket surfaces just as bad?