Non-electric chokes not opening.....

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ericinga
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Location: Cumming, GA

Non-electric chokes not opening.....

Post by ericinga »

PO ran the motors on this boat without thermostats. I plan to run with t-stats. The engineers designed the system with t-stats and there must be a reason. I pick up the t-stats tonight and will put them in before running the boat again.

The motors run extremely rich. After running the boat for 90 minutes last night, I pulled the spark arresters with the motors running and noticed the chokes were still closed. The temp gauges read around 100 degrees during the entire trip.

Do you think the t-stats will solve the choke problem? Warmer intake manifold heating up the bi-metal spring to open the choke? Should the Rochester carbs be upgraded to electric chokes?

I already need to rebuild the starboard carb due to a sticky float. Plan to do the port in the next month as well.

Thoughts?

Eric
Eric Spies
1989 32 SDFB
Twin 318s
Lake Lanier, GA
Marinette Boat
EWRice
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Re: Non-electric chokes not opening.....

Post by EWRice »

I assume you have the style of choke spring mounted in the exhaust crossover? If so, I would suspect that the crossover ports in the head/intake are plugged with carbon. Especially if it had been run for years without t-stats. Even more so if the restrictor is installed in the gaskets. Good way to check is with a IR temp gun. Should be above 200 degrees within a few minutes.
Muskegon Lake
1972 32' Express flybridge
"AL13"
Twin 318s
On board air & prime 920
1963 Thompson Super Sea Lancer
Graymarine 327
1961 Alumacraft 12'
'55 10hp Johnson
bobv
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Re: Non-electric chokes not opening.....

Post by bobv »

I had yhe same issue with mine. The problem was the springs were loaded up with muck. You do need to remove the carbs to remove the and inspect the springs. If that is the issue just clean the springs and the holes they sit in, You will also need new carb gaskets. These type of chokes are also adjustable.
Good luck
Bob
Fastjeff
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Re: Non-electric chokes not opening.....

Post by Fastjeff »

Aaaarggh! What moron runs a marine engine stone cold like that!

Yes, the t-stats will make one hell of a difference (and the oil will stay cleaner as well. Slug and acid form in cold running engines.) The chokes should open when the motor finally comes up to temperature. If not, some other actions are needed (let me know).

Now; which temp t-stat do you need? For RWCooled 140 degrees; for FWCooler 160.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington
guy2474
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Re: Non-electric chokes not opening.....

Post by guy2474 »

On 318 automobiles the intake manifold has an exhaust crossover passage that heats the floor of the intake for better atomization of the fuel and it also heats the choke well. As the years go by the passage carbons up where the port meets the head. No exhaust gas flow, no heat to the choke well. If you put your finger on the intake manifold by the choke well it should burn your finger after running about 5-10 minutes. I'm assuming marine engines have the same crossover passage. That is why your choke never comes open. I just disconnected the choke rod from the carb on my 318 and run with no chokes. You have to pump the throttle a couple times to start the engine with no choke, plus you should warm up for few minutes before getting underway or it might die out lean. Or you could pull the intake manifold and clean out the passage. Boats are normally started in warm weather. They hardly need a choke.
Fastjeff
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Re: Non-electric chokes not opening.....

Post by Fastjeff »

..."On 318 automobiles the intake manifold has an exhaust crossover passage that heats the floor of the intake for better atomization of the fuel and it also heats the choke well."

So do the marine 318s/ 360s.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington
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