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I don't recall the other I'll ask you.......have you checked the flapper (the thing that rattles on the end of one of your exhaust manifolds)? Is it moving freely and is the bi-metal coil sping intact? This is identical to the trouble I had when I first put headers on my SBC 25 years ago......I left the "heat riser" (as it is sometimes refered to) off of the installation. Since it was summer when I put the headers on problem. I took my parents up to Mass. and encountered some 35-40 degree weather .....and the thing would not idle until it fully warmed up. I then realized that the flapper channeled hot exhaust gas through a port that passes through the manifold under the carb .........once the bi-metal spring heats opens fully and the port goes dead since it's now "balanced"......since the flapper is "sprung" opens when exhaust flow increases ..but still "inhibits" full flow until its warmed up. This would be where I'd look if all the "normal" remedies fail you.

(didn't CJDave ask you this ? .....maybe I do recall that post- I don't believe that you answered him)


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