You are smelling raw/barely burnt gas. You are running rich. In these old cars, without emissions controls, you will probably always smell some exhaust, at the speeds we typically drive around town. It should not be unpleasant.

In fact the smell tells you the state of tune.

The cars need less richness in hot weather, I find as much as 3-4 flats of adjustment.

Follow the SU carb tune technique. If they need rebushing (throttle shafts) they won't tune for both idle and high load.

IMO, It takes a few miles for the engine to stabilize to new carb tune. It's like the carbon in the head has to burn down to a new composition.

I've been working on an air-fuel meter circuit with a simple led readout, but it's taking a while, along with other electronic projects that I am not expert at.
It would tell me my tune at all rpms, which may or may not help find the perfect needle.

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MPergiel, Walker, MI

Make sure there are no holes or leaks in the heater intake duct (dryer vent hose). Also look for rotten or missing firewall grommets.

it will defintely gie you worse & worse headaches,,i had a 59 bug that had hoes in the floor & even w the windows open it got really bad,,wish i didnt junk it.

So most of the exhaust fumes have dissipated from what most people probably expected: holes in the exhaust. Two holes were found and patched on the sides of the rear muffler and no doubt exhaust fumes were creeping in via the drainage areas and through whatever open areas exist on the trunk.

I still have some smell so I'll try to patch my torn shifter boot and try to figure out the trunk seal.

Thanks for all the helpful advice

Are you sure it is exhaust you are smelling? Is the pcv system plumbed properly and the pcv valve in good condition?
Make sure the hose from the intake manifold goes to the pcv valve and it in turn is on top of the oil separater on the side of the block. Another hose should go from the cap on top of the valve cover to the air cleaner. Any malfunction or calapsed hose in the system can cause considerable fumes in the passenger area.
Tom

Are you sure it is exhaust you are smelling? Is the pcv system plumbed properly and the pcv valve in good condition?
Make sure the hose from the intake manifold goes to the pcv valve and it in turn is on top of the oil separater on the side of the block. Another hose should go from the cap on top of the valve cover to the air cleaner. Any malfunction or calapsed hose in the system can cause considerable fumes in the passenger area.
Tom

Tommy;

Knowing that flow always goes from area of high pressure to area of low pressure, and applying this to the car situation...the Passenger cabin develops a low pressure by venturi if you have Windows open and are moving through the air...this will suck in fumes from wherever it can, including past Shifter (if you also have exhaust leaks up front) or Trunkseal, or Rustholes in the floor...obviously, you want to block these areas of entrance whatever way necessary, but until then, I'd try driving with either the Doorvents kicked open to scoop air IN (making the cabin a high-pressure area), or Vents closed, and running the blower on low(at least) to get the same effect.

Cheers

You are right to worry about inhaling exhaust fumes.

Carbon Monoxide is poisonous.

The trunk seal is usual culprit, but an exhaust tip that doesn't extend back far enough is also problematic.

I have some customers with 122 Volvos that opted to have the exhaust pipe turned so the pipe points out the side instead of straight back and the helps keep the exhaust from being sucked past the trunk seal.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com