I think an exhaust leak where the exhaust manifold connects to the exhaust pipe (often using a sintered donut) or nearby combined with a hole in the floorboard area could be smelled in the cabin with the top down even at speed. Actually, I KNOW it can.

My '65 Starfire vert also had the factory exhaust that exited out the quarters, and it would somehow back up into the trunk as well and make it into the car. Less of a problem with the top down, but jeez Louise!

 

When I first bought my 72 with 350, I had the same problem, but it wasn't an exhaust leak, it was a valve cover leak. The oil was seeping out and running down the block. The exhaust ports and manifold was making it smoke and that was getting into the car almost immediately. New gaskets a good cleaning and painting of the engine solved the problem.

 

i have the same issue, for me its the trunk, its beat up and few holes in it so its seeping in through back of the seat on my vert... and the choke is also wide open on my holley 750.

 

Sound travels well thru tubing
Stethoscope effect

Use a piece of tubing to search for leaks
One end near your ear, other end at various places a leak may occur

Manifold to head [were gaskets used? they leak.]
Headers notoriously leak at the head. They are better suited for race cars.
cracked manifold
manifold to pipe
etc.

Proper tune will make the fumes more bearable, but, any leak still has CO in it.

They did not behave that way from the factory, so it's a problem that can be found and fixed.

 

The temp gauge problem may be your temp sending unit. If the gauge is pegging hot and the car is not running hot I would look at the sender.

 

This thread is from 2012...