Need help with mercruiser 454 carburetor

I have a 1992 rinker Captiva 236, it has a 454 (7.4L) motor, i have had it for about 2 years and always assumed there was a carb related issue but it wasnt bad enough for me to take it apart to investigate but recently it's been running worse so I looked at it a few days ago, my problem is it doesn't have the stock carb on it, whoever had the boat before me put a carb made for the merc 4.3L on it and that carb isn't big enough for what my motor needs, I cant find the right carb for the boat because I don't have the owners manual or the old carb to get a model number off of and I'm hoping someone here will be able to tell me the right carb, I have been researching for a few days now but I'm not a mechanic whiz so alot of it is gibberish to me, any information helps, thank you

Tylerbauer23 said:

I have a 1992 rinker Captiva 236, it has a 454 (7.4L) motor, i have had it for about 2 years and always assumed there was a carb related issue but it wasnt bad enough for me to take it apart to investigate but recently it's been running worse so I looked at it a few days ago, my problem is it doesn't have the stock carb on it, whoever had the boat before me put a carb made for the merc 4.3L on it and that carb isn't big enough for what my motor needs, I cant find the right carb for the boat because I don't have the owners manual or the old carb to get a model number off of and I'm hoping someone here will be able to tell me the right carb, I have been researching for a few days now but I'm not a mechanic whiz so alot of it is gibberish to me, any information helps, thank you

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Ayuh,...... Welcome Aboard,...... Being a '92, it could be a Quadra-jet, which ended 'bout that time, or the Merc/ Weber AFB, which was intro'ed 'bout that time,....
If the Quadra-jet, it can be tuned to run on yer motor, no problem,.....
Post a picture of what you've got,.....

As bondo said if it is a qjet off a 4.3 it would just be a matter of rejetting.

if it is a 600 cfm webber or mercarb you will be down on power but may run all right otherwise

If you want a bolt on replacement a Edlebrock 1410 shoudl work nice but may be some issues to sort through on manifold, choke power supply, throttle bracket but nothing insurmountable

Merc racing used Holley HP850's on the 454 where the I/O and inboards got the Weber / Merc carbs

what carb is on the motor now. as Bondo stated, if it is a true Quadra-Jet, a bit of calibration and it will flow up to about 800-830 CFM

for help with Q-jets. https://cliffshighperformance.com/ or https://www.carburetor-parts.com/ Cliff or Mike have helped out many on the site.


regarding owners manuals for boats. back then there were none..... it was a 4-page safety brochure with a picture of the boat, a statement to not swim in the water with the motor running and a list of servicing dealers.

light reading on manuals. https://forums.iboats.com/threads/boat-manuals-owners-manuals.770690/