What heads do you have on the car?  I hve run across some heads that the hipo manifolds do not seal properly.  You should not be getting exhaust fumes from under the hood unless there is an exhaust leak in the system.

What tailpipe ends do you have?

Heads should fit those manifolds fine.  Gotta ask this one, but I am sure the answer is no.  Any rusted areas in the trunk floor or trunk dropoffs?

Is this a normal exhaust type smell or is it more like rich mixture exhaust smell?

MustangSteve wrote:

What heads do you have on the car?  I hve run across some heads that the hipo manifolds do not seal properly.  You should not be getting exhaust fumes from under the hood unless there is an exhaust leak in the system.

What tailpipe ends do you have?

Does the tailpipes exit at the REAR....or axle?
6sally6
 

Realizing these old carb'ed engines have a "smell" anyway.....I'd look into bumping up the ignition timing a few degrees to see IF that lessens the smell some. After that...-oh no I used a word I shouldn't have--u-ming the engine doesNOT ping under heavy acceleration...screw in each mixture until the engine starts to labor...then screw them out until the engine starts to mis-behave. THEN screw them in half way between the two.....OR...use a vacuum guage and adjust carb to get highest vacuum reading....then lower idle down to 700RPM or so.
6s6