I'm running a freshly rebuilt B20 F converted to dual Mikuni carbs on my 65 122 wagon; the engine seems to take longer to warm up than my 66'sedan (also a B20 F) with SU's.

Before I try swapping out the thermostat I'm considering other possible causes.

#1 - The 65' has the factory assymetric 5 blade metal fan, which I was forced to use because the car was hit in the front at some point, and the crossmember the radiator sits on was forced back far enough that the standard 4 blade fan won't clear the radiator. Too much cooling?

#2 - I had the cast iron exhaust manifold silver ceramic coated inside and out; it stays noticeably cooler than an uncoated manifold, and perhaps this is preventing the carbs from warming up enough to work properly with the choke pushed in, in a reasonable amount of time.

#3 - The Mikuni's are more touchy about temperature than the SU HS6's, or are not set up properly. When the engine has finally warmed up, however,it runs smoothly and gives much better acceleration than the engine with SU's ever did.

Thanks

Bill