How can you minimize fumes?

Fumes will be a function of a number of items:

1. Dino's do not have catalytic converters so regardless of what you do the exhaust will smell more and be more toxic. Nothing you can do here shy of cutting up the exhaust and adding cats.

2. Some engine oils can lead to more or less smelly exhaust. I'm not quite sure the reasons why and which ones but I am certain that engine oil can affect exhaust smell.

3. Under certain driving instances (mainly stop and go) the shape of a GTS with the top off can cause a curling of exhaust gasses into the cabin via the missing roof panel.

4. An improper operating ignition system or fouled/incorrect spark plugs will lead to incomplete combustion and increased exhaust smell

5. The biggest single factor would be the carb settings and jets. Running the engine too rich can make a huge difference to how the exhaust smells.

 

???
You may wish to clarify what exactly you're talking about.
Do you mean some fumes or exhaust smoke at the end of tail pipes when the engine is running ?
Or noticeable fumes (smell ?) of exhaust in the cabin ?
When the car is being driven or sitting at idle ?
When cold or warm ?
Etc...

 

Thanks for expanding. This could be caused by number of reasons, but without (in-person) knowledge or more descriptive details of the type of fumes or scents/smells you’re actually experiencing, difficult to offer anything specific.

Could be fuel or tuneup related.

Or oil or other fluid leaks, perhaps even on to exhaust system.

Or could be even as simple as individual tolerance for odors.
For example I know and have met a lot of people who are so accustomed to modern motor vehicles lack of exhaust etc, odors think there’s something wrong with (their) vintage car(s) just because it/they do have stronger exhaust and other odors since those, especially older high performance cars, don’t burn the fuels nowhere near as efficiently and thoroughly as modern vehicles.

Best advise at this time would be to take the car to your favorite mechanic/shop and ask them to evaluate, but if you don’t have one and have interest in me taking a look at it, you’re welcome to PM me as my shop is in Riverside (fairly close) and I have about 30 years of “professional” experience with vintage cars,, including Ferrari.

 

Sal, the first thing would be have the car tuned up and inspected. Carbs may be jetted too rich. Fuel lines, tanks and fittings may be leaking fuel. The exhaust needs to be checked too. Once all this is done you will still have to accept the fact that carbureted cars just have lots of evaporative emissions (VOCs) and smell. Carbed cars in the early emissions era got charcoal cannisters to reduce this somewhat.

Because of how clean modern cars are today we really notice the pre-emissions era ones.
See this thread. https://www.pro-touring.com/threads/135465-Catalytic-Converters-on-1st-Gen-Camaro-(68)

 

For safety reasons, I suggest making sure you don't have any ancient hoses that are oozing gasoline in places that aren't easily visible.

 

Could be setup richer than necessary. My DIno at one point was pushing ~9+% CO, and ~450+ppm HC at idle. Terrible to drive, and my clothes and hair stunk after a drive. I made it a quest to dial in carbs, and set CO to target a best performance value AFR. I can't recall the exact numbers. CO is now approximately half of what it was and HC is greatly reduced. The better I got the carb's balanced, the cleaner it became. I didn't have to change jets. I did also notice the float height is extremely sensitive. If I was getting associated cylinders responding on the lean side, when I double checked the floats, they were ever so slightly lower. Like 1/4mm (.010"0) had an effect. What a difference. The car is appreciably more enjoyable. Also, throttle response is better, it starts easier, and it pulls stronger. Here's a more simple thing to check - idle speed. imho, the engine emission is r e a l l y sensitive around 900 rev's. Sometimes raising the idle 75 rev's makes a gigantic difference. Make certain you are using a calibrated instrument to check this. The dash tach can be awful! What's condition of distributor? Advance sticking? If it stays too advanced when butterfly's close to idle, high HC = yuck! Some things to run by your mechanic?
Note that it still won't be as clean as a Honda Civic, But shouldn't have to be ridiculous.

Check out this excellent blog on the Dino DCNF carb's.
http://dino246blog.blogspot.com/2014/08/carb-tuning-1-weber-dcnf-carbs-and.html