1988 lm318 carburetor

Todml
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1988 lm318 carburetor

Postby Todml » Fri Aug 04, 2017 2:16 pm

Hello all, I have been reading forum for quite some time. Recently purchased 1988 Sportsman with fly bridge. I have many questions about systems on boat but I will post separate . Who would members purchase a Rochester quadrajet rebuilt carburetor from and are they fairly easy to tune once installed? Occasionally I believe the floats stick and gas leaks out the side at rod, also low idle does not stay consistent and drop Rams which causes engine to run rough. Thank you in advance for any suggestions.
1988 Sportsman fly bridge
Twin 318 Chryslers
Straits of Mackinaw
Duncan Bay Boat Club

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Busia
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Re: 1988 lm318 carburetor

Postby Busia » Fri Aug 04, 2017 4:40 pm

I used guaranteedcarburetors.com and would recommend them. They know what they are doing.--Ed
BUSIA
located in Ketchikan, Alaska. Gods country
32 foot Marinette express. (no fly bridge)
twin 350 Crusader (Chev 350) engines
1:1 Borg Warner velvet drive transmissions
Closed cooling (antifreeze in the engine)
Proud to be retired IBEW

TinLizzy
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Re: 1988 lm318 carburetor

Postby TinLizzy » Fri Aug 04, 2017 6:10 pm

Sounds like it needs to be rebuilt/cleaned. Rebuild kits with new needle and seat are usually around $40-50 bucks.
Rodney
1975 28 Express-Twin 318 Raw Water cooled
Portage Canal Waterway-Lake Superior

honestcharlie56
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Re: 1988 lm318 carburetor

Postby honestcharlie56 » Fri Aug 04, 2017 6:43 pm

I recently did the two quadrajets on my boat. Boat sank, sat for a year soaking wet, everything corroded as you would imagine. The quadrajets were a pleasure to clean and reassemble, when I took the vessel for her first above water ride since making the choice to be a submarine.....the carbs performed great. If you enjoy wrenching, take the time to research them and set them up according to your findings. They really are great carbs....even though they are overkill for a 318.
1990 Marinette 32 Sedan Flybridge "Hubba"
Twin Chrysler 318's

javalin390
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Re: 1988 lm318 carburetor

Postby javalin390 » Fri Aug 04, 2017 6:56 pm

Interesting post. As a former GM mechanic, and all around GM enthusiast, the Chrysler engines with Quadrajets always intrigued me. I rebuilt my Carter carbs last year, and they run fine, but the idea of switching carbs has been in the back of my mind. Are the 318 and 360 intakes the same? Anyone have a set of Q-jet intakes they'd like to sell?
Jim Elias
1974 37' SedanFlybridge
Twin 360 Chryslers.
Marblehead, Ohio

javalin390
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Re: 1988 lm318 carburetor

Postby javalin390 » Fri Aug 04, 2017 6:56 pm

Interesting post. As a former GM mechanic, and all around GM enthusiast, the Chrysler engines with Quadrajets always intrigued me. I rebuilt my Carter carbs last year, and they run fine, but the idea of switching carbs has been in the back of my mind. Are the 318 and 360 intakes the same? Anyone have a set of Q-jet intakes they'd like to sell?
Jim Elias
1974 37' SedanFlybridge
Twin 360 Chryslers.
Marblehead, Ohio

honestcharlie56
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Re: 1988 lm318 carburetor

Postby honestcharlie56 » Fri Aug 04, 2017 8:13 pm

Javalin390, I'm not sure how your engines run...but I was absolutely amazed how smooth mine were from the very beginning (after rebuilding due to sinking). I have no issues starting, smooth acceleration, all 16 plugs have a slight brown color. I'm still trying to burn fuel out of my tanks thats not so great, so I can fill with fresh fuel...I've actually complained about my 318's not burning fuel fast enough to accomplish this.
1990 Marinette 32 Sedan Flybridge "Hubba"
Twin Chrysler 318's

Fastjeff
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Re: 1988 lm318 carburetor

Postby Fastjeff » Sat Aug 05, 2017 7:22 am

The Mopar intakes interchange. I'll bet you already know that, if you want to put a Q-Jet on manifolds that used Carter AFBs, you'll have to get an adapter since the bores and etc are so different. Interestingly, adapters to put Carter AFBs and Edlebrock 1409s on Q-Jet manifolds are regularly available.

I went with Edelbrock 1409s on mine. They worked very well and improved gas mileage noticeably over the AFBs.

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

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Re: 1988 lm318 carburetor

Postby yooper » Sat Aug 05, 2017 8:38 am

I bought 3 books on rochester carburators prepping to rebuild my two. My problem was crud from old gas. Once I cleaned the fuel system up I began my carburator project. The rochester has a spring loaded filter screen screwed into the inlet. Mine were full of crud and letting unfiltered gas and dirt through. I got some metal gas line to run from the fuel pump to the carb and installed metal canister type auto filters in that line. I saved the original line. When these filters clog the gas is cut off. When I went to buy a rebuild kit the counter guy recommended a expert to do the work. I checked him out and decided to let him do the work. Glad I did. Heck a bucket of cleaner costs $25. The deal was $75 per carb with one day turn around. I take them off and put them back on. During the rebuild I found the kit did not include new mesh filters and the thin gasket was not right for the boat. The rebuilder found better gaskets and made me buy different floats and new mesh filters. True experts are picky. There are only three adjustment screws on the rochester. Two low on the front of the base are air/mixture screws. You turn them until you get the best rpm or manifold pressure. The other is the idle speed at the end of the throttle linkage. I had to leave mine at 1000 to keep it lit when docking. Youtube is full of information about these carburators.

Todml
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Re: 1988 lm318 carburetor

Postby Todml » Sat Aug 05, 2017 8:58 am

Yooper are you located up in the Soo, if so is your carburetor man still available in that area?
1988 Sportsman fly bridge
Twin 318 Chryslers
Straits of Mackinaw
Duncan Bay Boat Club