Logo
FULL SITE MENU

1992 OMC Cobra 5.0 Choke

D

ddygert

New member
I'm confused by this carb. There is a fitting that appears to be for a vacuum line that I do not ever recall seeing anything connected to it. Is there supposed to be a vacuum hose connected to it? If so to where on the engine? Also- Any tips on correctly adjusting?
 

Attachments

  • Carb.jpg
    Carb.jpg
    62.2 KB · Views: 107
youtube and the internet has a lot of information on how to adjust an electric choke, but as for the vacuum port on the pot, it looks like a holley carb.. is it a marine carb or a automotive carb?.... on the automotive carbs the vacuum port is supposed to be connected to a vacuum port on the base of the carb, which when the engine is running it allows a small amount of airflow and keeps the choke spring from overheating...............im not familiar with this feature existing on a marine carb

most holley carbs have this airflow function ported direct, internally...
 
Thanks or the reply. Its a Holley carb and is the same carb since we purchased the boat in '96. I found the same carb online at Jegg's and it also has the fitting.
 

Attachments

  • Image-1.jpg
    Image-1.jpg
    39.5 KB · Views: 86
i wouldnt concern myself with it... our marine engines run cooler than automotive engines and if the bi-metal choke spring hasnt had a problem by now, it probably wont ever...
 
That air inake hole is to allow some air flow over the choke coil so it does not overheat. It has to get 12V to keep the choke open the whole time the engine is running. And yes in the old days of exhaust heated chokes, there was a metal pipe that went into an exhaust cross over (GM engines ) or a section of the exhaust manfold (Ford engines) that provided hot air to heat the thermostatic spring to open the choke. Same principal different actuation. Just don't block that hole!
 
louc said:
That air inake hole is to allow some air flow over the choke coil so it does not overheat. It has to get 12V to keep the choke open the whole time the engine is running. And yes in the old days of exhaust heated chokes, there was a metal pipe that went into an exhaust cross over (GM engines ) or a section of the exhaust manfold (Ford engines) that provided hot air to heat the thermostatic spring to open the choke. Same principal different actuation. Just don't block that hole!
Click to expand...

Bingo! This is likely a carry-over from early days.


The thermostatic spring is a "Helix".
By default and when cool, the Helix linkage closes the choke chimney off.
As the electric heating element warms the Helix, the Helix now opens and holds open the choke chimney.


These should actually be called an Electric "UN-Choke" ..... so to speak! :D :D

 
Yep electric un or de choke!
When I converted over to the Holley 4160 from the QJet with the well or divorced choke, I wired it in such a way that the choke would get power only when the engine is running. I used a waterproof Hella relay with the power coming from the B+ on the Alternator and the relay being triggered by the L2 terminal (indicator light) on the alt. This way the current draw of the choke heater is not a strain on the alternator diodes because the the L2 is only triggering the relay.
 
That should work well.
Often the key switch being "ON" will begin the Helix heating element operation.
With your setup, the opening of the choke chimney will not begin until the engine is actually running.


.
 
Back
Top