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Discussion Starter · #1 ·
Car stalled a few times at a low steady cruise today. Outside air was 87 and engine temp 190'ish. Checking carb and found vapor coming out of the front bowl vent which I have never seen before. Anyway as the video shows when I put my finger over the vent tube it shot fuel out and the engine stalled. Mechanical pump with 6-7 psi and fuel level is correct. The secondaries do not do this. Am I boiling fuel here or is the pump sucking air from someplace?


 

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A few ideas Fomoco make sure float isn’t sticking. You can tap on the float adjusting nut with a rubber hammer or plastic screw driver handle end. Doesn’t have to be hard , but try a few taps and try again see what happens. It get a little vibration going that can un- stick a float. Of course make sure float isn’t to high either.
 

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Was the carb heat soaked?
Intake manifold cross over blocked?







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Discussion Starter · #4 ·
Float bowls were at the proper level no aeration through the large sight glasses that I could see and the carb itself was warm but not hot. The stainless steel braided fuel line and in-line aluminum filter were extremely hot to the point I could not keep my hand on it. The next day started it up everything was fine including putting my finger over the vent and nothing happened. Took it for a drive and after it got heat soaked it started doing the same thing. not sure why it’s not doing it on the secondaries but I’m pretty sure I narrowed it down to the gas which I bought at a different station than I normally do and I no longer have the composite 1 inch carb spacer. This places the in-line fuel filter just touching the top of the radiator hose. I ordered a 1 inch four hole spacer and give that try. I will post back with results.
 

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Discussion Starter · #5 ·
Crab spacer cured the fuel boiling issue however, the engine does not like it. Tip in almost feels like its missing and sluggish to about 2500 rpms. This is a straight cut 4 hole so I will put my open spacer on and try opening the 4 hole up like a power cone.
 

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HI I'm talking about the secondary's of a 4 barrel carb not the transmission kick down..
Its called bog when the secondary's kick in too soon causing to much air flow for the RPM's of the motor.. Vacuum secondary's are the recommendation for an automatic for that reason.. and that is adjustable to set it for the best performance.. Mechanical secondary's open the secondary's to soon for most automatics and cause Bog down.

good luck take care be safe
tim
 
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