Hi. Need to find a source for a replacement of the exhaust manifold heat riser spring (only) on a '57 235 Chevy inline 6. (Heat riser valve goes in between the intake and exhaust manifold. It has butterfly plate with a counterweight on the other end of the shaft and the coiled bimetal spring on the other end)
I've checked the usual online classic truck dealers but no mention of this part. Thanks Wayne