77 running hot in traffic, fine on highway

[timspider]

I just replaced the radiator. Got a new oem for $170 US so had to take advantage of that. Just put it in last night and for the first time, the temp did not run up during warm up.
Now to figure out whey the carb is being finicky.
I know I have a leak in my downpipe (new 1-2-4 maniflod and downpipe just arrived this week and waiting to install with new hi performance exhaust pieces when they arrive)
could a leaky downpipe manifest in carb backfiring?
sounds like a long shot, but had to ask.
getting closer every day

[TX82FIAT]

You might want to start a new thred with the backfire issue so some of the folks that know a lot morte than me can chime in. An explosion that sounds like a backfire in the inlet manifold, carburetor/throttle body, or air cleaner of could occur when the intake valves are not shut prior to fuel combustion. A lot may depend on where the leak is specifically allowing air to have access to flame.