In case some of the information early in this post is confusing to a future reader, the page referred to in this statement in the post above is mistakenly associated with this topic:
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The only direct mention of the heat riser I can find in the 54 Truck Service manual is page 6-57, and that's to turn off the auto-choke. Which was optional to begin with. Model BC carbs were only equipped on trucks with automatic transmissions.
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The information on the
Rochester [b]BC[/b] (model [b]B[/b] with automatic [b]C[/b]hoke) does not seem to refer to the manifold heat riser or the heat control valve that I think is the topic of this discussion.
Now, I'll go back to to being amused by statements about GM putting a supposedly unnecessary (or non-critical) device on the vast majority of its 216/235/261 and 228/248/270 engines (and on many/most 302 engines). And, I'll be puzzled by why GM would spend the money on putting this device on most of those engines, if it was/is not really useful/necessary?
Natter on with unsupportable opinions and speculations . . .
