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Merc 98 High Altitude Carb

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cactusblues

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"I've got a '78 Merc 1

"I've got a '78 Merc 110 (9.8hp) with carb problems. This was my father's engine and he was a Merc dealer/mechanic. I have the shop guide for this engine. He had the engine set up to run well at 3000' elevation. I am now trying to use it at 8000' in Arizona's White Mountains. It would not develop full power with the .045 jet he had installed. I looked up in the manual that at 7000+, this engine should have the .035 jet installed. I have had this done, but now the engine will not run at rpms above a fast idle without acting starved for fuel, run for a moment then start to die unless you switch on the choke. Still no full power rpm. I have tried adjusting the mixture screw, but not much success. I also could not find the .045 jet recommended anywhere in this manual, so wonder what might have been behind my father's decision to install that jet for 3000' usage. Any ideas?"
 
"Face it, at that altitude it&

"Face it, at that altitude it's gonna be weak. Are the plugs coming out dark colored?


Jeff"
 
"Thanks Jeff,

Plugs are fin

"Thanks Jeff,

Plugs are fine. I'm not expecting sea level performance, but should be able to turn up the rpms to something equivalent to normal with an appropriate mixture hitting the cylinders. If you have the elevation-to-jet recommendation for this engine, what does your manual recommend for the 1971 Merc 110 operating at 7000'+ elevation? The Mercury shop guide I received with the engine from my father doesn't cover this model year, and I'm running with jet recommended in this version of the guide (.035)."
 
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