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I don't have a 1978 CSM & I haven't read a 1978 CSM, but sometimes torque values are not listed in the section which has a list of torque values; instead, sometimes torque values are listed in the section which specifically addresses the item(s) i.e. in the carburetor section itself, perhaps.
I can't recall where/when I took this image (or, did I steal it from someone else?), pretty sure it was from my 1971 CSM - sorry. At any rate, 15 ft - lbs Carburetor to Intake Manifold Bolts. Use w/ caution since it's not from a 1978 CSM (that I'm aware of).
I would think that since they are basically the same carb and bolt materials and sizes, using 10 or 15 lbs/ft to clamp it to the intake is plenty. Either one is just more than snug as it is. Although I'd trust the year-specific CSM just to be sure.
My go to is the smallest diameter 1/4 nut driver.
Something like 1/2".
I snug and tug them up on initial install.
Then run through a couple heat cycles and repeat.
Never more than just check to see they are snug.
I have a '78 CSM. V-8 engine torque specifications are on page 6A3-38.
The carburetor torque spec is only 10 ft-lbs. It is 15 for the V-6 engine.
Man I totally missed that. I think I might have overtightened it after it backfired out the carburetor base. The gasket must be bad. Thank you for pointing it out.
The Q-jet air horn is very susceptible to warpage from over tightening. Excessive warpage will cause all sorts of problems down the road. The carb to manifold bolt torque has been addressed already in this post. The screws that attach the air horn to the main body need only be snugged. I don't recall seeing a torque spec for the air horn screws; my 1967 CSM states "tighten securely".
