1960 1600 difficult to start after driving

[michaelteleha]

i have a 1960 cab with a 1600 motor and zenith carbs. if the car sits over night it will start right up. 2ed crank all the time. when i am out driving the car if i try to start before the engine is "room temperature" i have to crank about 4 -5 long times and keep the accelerator all the way to the floor. (trial and error to work this out) It is almost like there is no fuel? once the motor starts, slow start up, then she runs perfect. maybe a little high on the idle but ok. before i mess with something that is not really a problem (slightly high idle) i want to fix this.
i turn the fuel off when i park. i have tried leaving fuel open (on) and still the same issue. one the car is running she runs great.
any ideas?

[Phil Planck]

Try turning the fuel off before you shut it down, and run the engine until it runs out of fuel. This may take a minute or two. See how hard it is to start after this test. If it starts right up, then you know somehow, too much fuel is causing your problem.

[David Jones]

Sounds about normal to me but you may be exacerbating the problem with turning the fuel off. Unfortunately modern fuel is more volatile than what these cars were designed to run with and because of the high temps that accrue in the engine compartment the carbs tend to allow the fuel to vaporize as soon as you turn the engine off. Two things happen
#1 the fuel boils off and as it is heavier than air it sinks down the manifold and sits in the inlet tract where it makes for an over rich mixture for starting when hot so putting your foot to the boards and cranking is the best way to get it to fire when hot.
#2 Because you turned the fuel off you now have to fill the fuel bowls again which can also extend the time to get fuel in to the carbs and vaporize correctly once you have the rich mixture flushed out. Try just turning off the ignition and try to do an idle down to cool the engine before turning off then a half throttle start.

[Martin Benade]

This sounds normal to me too, mine is always flooded when it is time for a hot start, I do what you do. If you have 6V it will probably start, with 12V it will for sure. To me this is the major benefit of 12V conversion.

[Thomas Sottile]

I do not think this is normal, if all things are correct the engine will start hot or cold maybe a few more turns when it is extremely hot or cold. There a lot of thing to check. start with the cleanliness of wire contacts. adding 12 volt just masks the problem.

[michaelteleha]

i like the run it dry idea and then crank and see if same result. My question about this is why does it start so easy when i let the car sit overnight with the fuel off?

the car runs cool (in my one car reference point opinion). i have a cylinder head temp gauge i put on the #3 cylinder. When out and about, i drive the car till cylinder head temp is about 250-275 and then stop. for reference i am about 300 on the highway at 65mph and 350 - 380 at 75mph.. do not go there but was part of the working out the range of the motor. at these temps, the oil temp gauge is at the bottom of the thick green to about 30% -in normal green range -at 75mph). so i don't know how hot it is at the carbs when parked but the days are still only in the 75-80 range and good time to resolve. it will only be more difficult this summer when the low is in the low 80's. all ideas are appreciated. i will take to Zims and they will have a few ideas but i hate paying shop rate to do the homework that i can do and enjoy.

[Larry Coreth]

Guys,

I have been driving 356's for several decades and in particular my Speedster since 1984, so I have seen several versions of Federally (EPA) mandated fuel formulas each of which had its bad attributes about which everyone complained loudly. Now a hot 356 motor at restart is lazy, the carbs are hot, the intake manifolds are hot, etc. all conducive for fuel evaporation, not flooding. Unless your float valves are seriously leaking which is easily confirmed, yank the air cleaner off and look down the throat, if you see fuel dribbling out of the secondary venturi, you have a problem ! Now I have found the best hot starting method is: turn fuel on, begin cranking the engine with closed throttle ( 3-5 sec), then pump throttle 2-3 times ( only to half throttle, no need to carried away here), then hold at ¼ to ½ throttle, it should come to life. Once started hold at 1000-1500 RPM to allow the intake system to cool off for 30 to 60 sec. Some hand throttle is good here. Drive off and reduce hand throttle as required to get normal idle.

[Jay Wiener]

Check the valve adjustment. I used to have this problem with my 63 coupe. The valves were too tight. After adjustment the car was fine

[George Walling]

I had a similar problem with my speedster and zenith carbs especially when the summer temp comes any where from about 80f on up what I did was put a glass fuel filter inline in the engine compartment and could see the fuel boiling in the filter so took a bottle of cool water and poured on the steel line and filter car would start. now my fix was easy as we can buy non ethanol fuel in Oregon so all I burn is that fuel and it is 92 octane. So I would say you probably are experiencing boiling fuel. one more thing to check and good luck.