Webers & washers don't mix

[Rouser]

OK, it turned out to be a dumb idea later, but it seemed kinda smart at first ...

Once Upon A Justalittlewhileago, I spanked some persistent, tailgating adolescents (Two Kids and a Kia … what's next?) on my way to a client. As I exited I-4/Tampa Speedway, and upon re-entry into normal space, I noticed by beloved starship was idling awfully nasty. With the engine/carbs within earshot, I could hear "suh … ssss … suh … suh … ssss" and the tach was fluctuating. It wasn't much further, so I rough 'n rumbled the rest of the way.

After finishing my business, I walked to the parking lot, popped Le Hood, and started the car. She chubbled her way into some sort-of idle, wherein I pondered the engine looking for the "suh … suh … ssss … suh" culprit. "Holy Crap! The right-side Weber is loose!", just bobbling on the manifold. While scratching non-existent scalp and neck itches, some thermal-dynamic-dissimilar-metals theories and formulas flooded my cranium; "Damn, I guess putting those steel washers between the aluminum-alloy carb bodies and mounting nuts was stupid, stupid, stupid. You never worried about the nuts scratching the bodies any other time, why then after the last rebuild a few months ago? Knucklehead; heat, cold, expand, contract. Got it?"

So, I broke out my adjustable metric tool (crescent wrench), removed the 4 washers, tightened the carb down snug, and then discovered the other carb's nuts were less-than snug. I thought, "Boy, the 914 Forum is gonna love this!" as I tightened down the other side long enough to get home and remove my "upgrades".



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Rouser!

[Joe Ricard]

Hmmmm? I just wonder. I am using the bent steel washers on my carbs. so far I haven't left the darn things on long enough for them to vibrate loose. Did have this problem with my 928 and the exhaust flanges. Finally got stainless bolts and copper nuts. 5 years later still no leaks.

[Rouser]

I can't say for sure if thinner, bent-type washers will have the same effect, as the washers I was using were a bit thicker.

I had to do the same copper-nut thing you did to an '82 280ZX Turbo I once owned. That's RIGHT! I RICED! I came around, though; OK?!!!



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Rouser!

[914GOD]

The different thermal expansion rates of steel and aluminum did not have any effect on the tightness of your bolted joint....it was loose to begin with!

The joint should be as loose as it is going to get when it is cold. As the thing heats up the metal expands (steel and aluminium) and the joint always gets tighter. If the bolt where aluminum and the flange where steel this would be a different story as Al expands more than steel, but in this case, it was loose to start with.

By the way, tightening the bolts directly on the aluminium flange very well would keep them tight...because they are dug in to the aluminum flange, not for any thermal expansion reasons.

Hope this clears things up....

Sean