Carb Adjustment 1992 Mariah 4.3 Litre
What are the adjustments for the two screws on front of carb? Rochester Quadrajet.
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Re: Carb Adjustment 1992 Mariah 4.3 Litre
Hi seapoo,
They are the idle mixture screws. I suggest you leave then alone unless you're familiar with the procedure for adjusting them, To perform the adjustments correctly, you need to have the ignition in "Base Timing Mode" first. The procedure is explained in section 5C starting on page 12 of the Mercruiser 4.3L service manual. WetWilly |
Re: Carb Adjustment 1992 Mariah 4.3 Litre
Is there a default adjustment to start off with? Motor was smoking at idle after Marine adjusted both screws. They had them 3 turns out. I put them to 1.5 turns out and now it idles great with no smoke. Just want to ensure I have them at factory settings. Please advise.
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Re: Carb Adjustment 1992 Mariah 4.3 Litre
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If I recall correctly: One screw would be the idle mixture and the other the low-speed mixture. I tore-down and rebuilt those a couple times, back in the day. Jim |
Re: Carb Adjustment 1992 Mariah 4.3 Litre
Hi seapoo,
Wow, three turns, huh... that way too much. I would seek another mechanic who knows what their doing! The manual says to start with the screws 1.25 turns out to start, so your right in the ballpark! To adjust them as best as possible, follow the manual's procedure. BTW, Per the manual, the carb is a Weber, not a Quadrajet four barrel, although they look the same. Oh, and SEMIJim, on the four barrel Webs and Quads, the two screws in front are the idle mixture screws for the front two bores (see carb exploded view, Pages 5C-18 and 19) and I was Holly man too except for some reason, I've got an Edelbrock Quad on my '70 Mustang, go figure... :confused: WetWilly |
Re: Carb Adjustment 1992 Mariah 4.3 Litre
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Jim |
Re: Carb Adjustment 1992 Mariah 4.3 Litre
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I know what you mean Jim, A LONG TIM AGO for me too, but I still remember them well, I think... :rolleyes: Remember American Graffiti? That Mel's Drive-in was in my old home town, I can still recall the Car Hop Girls! ;) A getting older WetWilly |
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