i have a big(expensive)BC in my b-body,3 row w/ tranny cooler,can,t get the car to stay under 215 at cruiz it coolds down a little at lights,my other b-body w/slightly more comp runs 180-190 all day w/a cheapy sumitt 2 row.iv been all through the tune nothing makes a diff.any suggestions as to what im missing.

Do you have a fan shroud? I do and my car runs at 180 in any weather.

Gotta be in the tuneup.

If it can cool itself when its sitting still at idle, it "should" cool even easier when you're rolling down the road and putting even more air through the rad.

Something is going on with the tune.

Whats your initial timing, and total timing, and what rpm is it all in by?(check with vac advance unhooked).

What carb are you dealing with? Have you tuned the idle mixture screws with a vacuum gauge? The idle mixture often has a pretty good influence on the air fuel ratio at cruise, because you're usually not in the main jets yet at a cruise.

Where is the vacuum advance hooked up? Full manifold or ported vacuum? They cool better when run off of full manifold.

And im reaching here, but what converter, and do you have an external trans cooler? If its a high stall converter generating a lot of heat and you only have the cooler in the rad...its possible its not doing enough. The trans fluid could be getting hot enough to affect coolant temps.

Ok at idle/stoplights but hot when cruising at speed, is that correct? If so toss the stat for a 1 hr test & what jets and what is the timing at the offending rpm while cruising (run it up to that rpm in your driveway & see) unless you've already dealt w timing/jets