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Discussion Starter #21
I got the Gates 31640 cap. Fits tight. After letting the car sit in the sun half a day I open the cap and didn't hear anything. Don't know what that means.
 

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I usually get a psst when I take my gas tank cap off. Should there be pressure there or not. Mines a 70 XL. When I read the manual it talks about a "Fuel Evaporative Emision Control system" but says this was only fitted to California cars. Mine was first registered in Tampa Florida.
 

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the cap lets air in not out.
if pressure is building up in the tank, you need to look elsewhere.
Well.... not all of these mid 60's cars have any other vent.
Usually the cap is the only one.

My 66 Galaxie has no separate vent tube or otherwise.
Only the vent in the cap. That's it.
 

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apologies, let me rephrase - the vented, anti-surge gas cap that we are discussing in this thread only lets air in- not out.
the "standard" cap that would have come as original equipment on the car wasn't sealed, and would let air/fumes travel in either direction.


i think trying to seal something that wasn't designed to be sealed is probably a bad idea.
 

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Opened the hood yesterday after a run and when I looked at the fuel filter (It's a transparent plastic one) I could see the fuel bubbling (Looked like it was boiling, but it wasn't that hot) so I went and released the fuel cap. Go the usual pssst. then the fuel stopped bubbling in the filter. Still waiting for the new cap to arrive.
 

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yikes....

thinking out loud: so this means that your fuel pump is having to pull against a sealed tank, therefore creating suction/vacuum in the tank.
do you ever experience symptoms of fuel starvation?
 

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no not really.
A few times I have had problems starting her when she's hot, but that seems more like an electrical problem. (Turns over really slow but starts eventually).
 

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A few times I have had problems starting her when she's hot, but that seems more like an electrical problem. (Turns over really slow but starts eventually).
gotcha. that's heat-soak, usually from an overheated starter (too close to headers, etc).
 

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Discussion Starter #36
Having too much timing advance can challenge a starter also.
I used to keep my distributor cap a little loose and when the car wouldn't start back off on the timing a little, start the car, and put the timing back.
 

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gotcha. that's heat-soak, usually from an overheated starter (too close to headers, etc).
Been told that before, so tried wrapping the starter in some of that heat protective material.
Didn't make any difference, but like I said it's kind of stopped doing it now.
 

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Having too much timing advance can challenge a starter also.
I used to keep my distributor cap a little loose and when the car wouldn't start back off on the timing a little, start the car, and put the timing back.
why would that make a difference only when it's hot though?
 

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Discussion Starter #40 (Edited)
The higher temp increases the pressure inside the cylinder, according to Boyle's law. Retardimg ignition could mitigate the problem. Just a guess
 
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