Need help with mercruiser 454 carburetor

[Tylerbauer23]

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

 

[Bondo]

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

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,.....

 

[Scott06]

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

 

[Scott Danforth]

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/