Fuel Evaporation

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wheelsport

wheelsport

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I have to crank for a few seconds to start my '65 Cuda after it sits for a week or two. When I shut it off after a drive, I smell gas fumes. I believe I have a problem with fuel evaporating in the carb. Originally I thought fuel was leaking from the carb so I pulled the air horn and filled the bowl with kerosene and let it sit over night. The next morning the kerosene was still there. I'm thinking about placing a spacer under the carb to better insulate it from engine heat. Does anyone have any other videas about this problem?
 
My 66, 273 4 bbl did the same thing. A carb spacer helped a lot. But after sitting a week or two I would pump a number of times when first turning the key to fill the bowls.

Now I have an electric fuel pump so that problem went away, lol.
 
Making sure the choke is shut tight helped me a lot with this issue. Helps pull the gas in faster.
 
Yep I just put a 1/2" phenalic spacer on my buddy's 383 Dart, really helped a lot plus it seems to run better.
 
Kendog 170 said:
Making sure the choke is shut tight helped me a lot with this issue. Helps pull the gas in faster.
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I don't think so Tim! The choke just richens the mixture for a cold start. It doesn't make the pump any more efficient.
 
A spacer will help keep the fuel cooler during running and may help a bit after shutting the engine off. (hot soak) It won't prevent the fuel from evaporating after it sets for a week or so. Ethanol is especially bad for that.
 
66fyssh said:
My 66, 273 4 bbl did the same thing. A carb spacer helped a lot. But after sitting a week or two I would pump a number of times when first turning the key to fill the bowls.

Now I have an electric fuel pump so that problem went away, lol.
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A small electric prime pump and a momentary switch is a good plan.

Here's a thread about the subject and a part number for a small charge pump on post 25.
Losing Fuel
 
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I cheated though Mike. I needed an electric pump for my new 5.9 since there isn't an eccentric!!

But I like the idea of a small electric pump to help with evaporation issue.
 
I have checked with summit and all the other suppliers and they don't have a spacer that fits my BBD Carter application. I might need to make my own spacer.
 
Likely a combination of evap, fuel boil, and vapor lock. "This new ****" they are calling "gasoline" has a fair amount of alky in, and it boils very easily, and has a much higher vapor pressure than straight gasoline

Before I converted mine to EFI, and later tore it apart, I went to a rear electric pump, added a carb heat isolator, and made a fuel return system much like my 440-6 or the hemi's used, and later jeeps. You can buy a couple of Wix fuel filters that already have the return orifice built in. I used to know the part no.
EDIT I ain't fully senile yet!! Wix 33040, 33041
 
wheelsport said:
I have to crank for a few seconds to start my '65 Cuda after it sits for a week or two
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Totally normal.

If I drive my dart (67 273 2bbl) and let it sit a week, 2 pumps, crank, another pump, crank, usually fires up.

If I drive it, then the next day drive it, 2 pumps crank and it usually starts.

BTW, a new insulator usually comes with a rebuild kit.

Found just the 1/4" insulator...
Carburetor Flange Gasket for Carter Holley & Rochester
 
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I was having the same problem on my 65 with a 273 bbl. I tried everything and what I ended up with is: An electric fuel pump with a return line to the tank. A three nipple fuel filter was used. I made a adjustable run time controller that only runs when the car is first started. I used a 555 chip with led light. Works really well. I plan on installing this on all my old cars with carb.

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I mis read this from Op's post. Thought he had issues starting when sitting a week but a few seconds is good.
wheelsport said:
I have to crank for a few seconds to start my '65 Cuda after it sits for a week or two.
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I had to crank a lot when my car sat a week and by making sure the choke was completely closed fixed the issue.

As for
toolmanmike said:
I don't think so Tim! The choke just richens the mixture for a cold start. It doesn't make the pump any more efficient.
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My bad. But you aren't 100% right. My name is Ken. lol
 
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