Airbox with spider can also blow ?

[prebordao]

While tracking air leaks, after removing a header, i found my airbox is of the late kind with the metal spider.
It seems that the weld between the 2 halves is slightly split and 2 of the inner screws were a bit loose.
I thought that the spider solved the blown boxes syndrome. I was wrong ?

[Peter Zimmermann]

Yes, an airbox fitted with an internal diffuser can blow. Many factors can be involved with why an airbox blows, such as operator error (incorrect starting procedure), out of tune engine with incorrect fuel mixture, incorrect cold control pressure (critical to avoid super-lean starting mixture), fuel distributor issues, sensor plate height adjustment wrong, hand throttle (1974/75 models) set wrong, air leaks in system, etc. The diffuser normally doubles the life expectancy of earlier non-diffuser boxes, but all the other stuff must be right as well.

BTW; the original airbox on my '82 SC lasted 192K miles. All '81-83 models, and roughly half of 1980 cars, had the diffuser box fitted by the factory. If you think that your box might be original, look for a blue sticker on the flat side of the box, right hand side, below the fuel distributor. The sticker will be about 1.5" x 2". Sorry, for some reason I've never photographed the sticker!

[prebordao]

No, it can't be original. Mine's a 74 so no diffuser back then.