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Flat washers or lock washers in place of bevel washers? (Carbs to intake manifold)

Discussion in 'Technical Q&A' started by Mike328, Jan 21, 2004.

  1. Mike328

    Mike328 F1 Rookie
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    I'm about to put my carbs back on to my 1978 308.

    The carbs are attached to four intake manifold openings via studs/bolts, nuts, and washers.

    I decided that I wanted to use all new hardware (nuts and washers).

    The washers that were on there were these "Bevel Washers" that I had never seen. Basically, towards the middle they taper up a bit.

    I was told that they used these, so they only had to make one type of washer for both flat washer and lock washer applications... That's what the guy at Lowes said, anyway.

    So, what kind of washer do I use in its place? Flat or lock? They also had these "wave" washers, but I don't think that's what I want...

    --Mike
     
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  3. Steve Magnusson

    Steve Magnusson F1 World Champ
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  4. Mike328

    Mike328 F1 Rookie
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    Those are definitely the right shape. I'll have to check on the size, I'm sure they have it.

    What the heck do these washers do? Will others substitute in my particular application?
     
  5. bill308

    bill308 Formula 3
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    Interesting. My car was fitted with flat washers and nylock nuts. I replaced them with new. Are they really supposed to be Belville washers? I can make a strong case for them being Belville washers. The issue is that the carbs are some unknow alloy, probably aluminum plus something. It's likely this material expands more than the steel studs with increasing heat. This puts a lot of tension on the stud when the engine is hot, compressing the base gasket. When everything cools down, the carb is now looser. I guess this is the reason that the carb fasteners always seem to loosen up. Maybe I need to get some of these washers!
     
  6. Peter

    Peter F1 Veteran
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    I've had no problems using lock-washers in place of the originals...
     
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  8. Steve Magnusson

    Steve Magnusson F1 World Champ
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    I can't think of a "better" substitute -- Bellevilles give even, well-distributed loading at low preload, and, as bill308 said, they can absorb more deflection than just a stud with a flat washer before going to a zero load state (everyone, including myself, always overtorques these ;) -- i.e., it's such a "soft" overall connection that the nut should be used to just flatten the Belleville rather than stretch the stud significantly). I think you'll find that most throttle bodies use them as well at their similar flanged, bolted connections.
     
  9. Mike328

    Mike328 F1 Rookie
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    So if I got 'em, should I just reuse 'em? I'm sure they're the 25 year old originals...
     
  10. Steve Magnusson

    Steve Magnusson F1 World Champ
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    If the free height still seems reasonable then functionally they're OK to reuse IMO (unfortunately, the Fabory data doesn't give free height). Whether or not the plating/appearance meets your requirements is subjective.

    I'm not saying that other things won't work OKish too, but IMO this is similar to discussing whether a SIMPLE BOLT + NUT can replace the (softer, with larger non-zero load range) stock COIL SPRING + BOLT arrangement on the F exhaust flange connections -- sure, it sort of works OKish, but it's not a plus -- JMOs.
     

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