EFI to Carburetor
 

I have a 1994 Mercruiser 454 magnum MCM EFI 385 hp that \i would like to convert to a carburetor. If it had a newer efi system I wouldn't even consider switching but it has been one thing after another. I think the ECM may be toast now. The boat sat for 9 years and was not properly winterized. I have put in a rebuilt base engine but cannot get it to run right. What is involved in switching to a carburetor ? Intake, carb, distributor, fuel pump ? Are there kits available ? Any help would be greatly appreciated.

its easy and will run great use a 1410 eldebrock

Remove the motor EFI harness leave the motor harness. Depending on which serial number, would run alarm switches from the Tan/Blue wire. To determine would need serial number

I have a 1998 Doral with a 5.7 mercruiser. Is there a carburetor that would replace the efi unit on it?

Eldelbrock 1409

as far as i know there is no kit but it can easily be done,i have a boat with a 502 mag efi i am converting right now.you will need a carb,intake manifold,ignition system and a low pressure fuel pump.i have done several of these conversions and all the boat owners say it made their boats run a whole lot better.

I fid the 502MPI to carb. Used the EST distributor from the MPI. Being a Gen V the MPI had the sea water pump mounted mechanical pump, which I used. Removed vst electric pump set up of coarse. Luckily the dist had the module with advance curve they use in the Voyager Ignitions. If yours doesn’t do advance, you can swap in a module that does. We have noted these modules in the past on OSO and other places.

Hi,
When you say "ignition system" do you mean coil and distributor ? Any other components ? Thanks !!

Has anyone done this with 565's ? I want to get rid of all the computer stuff and DTS and go back to old school mechanical throttles and shifters

the one i am currently doing is getting a msd dist,ignition box and msd coil.

Doing some shopping now. What do think of a Edelbrock 7163 Performer RPM 2-R Intake Manifold ? It is built for rectangle ports and should work ? Also, the Edelbrock 1410 should fit ?

Yes and yes. Also if you already know Holley style carburetors Quickfuel makes some very nice marine carbs. (have one on my 383) The intake you asked about has the right mounting size (square bore) for the Edelbrock Carbs.

What manifold would you suggest?
 

what manifold would you suggest?

Summit Racing has a lot of Carb/intake combo packages for small block Chevy. I couldn't find a combo package for my application (Big block rectangle ports) but was able to find my parts separately. I don't have the technical background to suggest an intake manifold for your application. There are many variables, headers ? Cam ? etc etc...But i'm sure with a little more info on the engine, someone here could help out. Good luck.

I have a 96 454 Mag and the previous owner did the conversion. I honestly have had nothing but issues out of it, not necessarily the carb but the fuel supply.

If the boat sits more than a couple days the external electric fuel pump is unable to get fuel back to the carb. Yes, I removed the entire seat and floor to access the tank because I thought it was the anti-siphon valve. It's a straight barb with no check valve inside. It can be done but I just haven't had the best of luck......

I highly recommend using the Daytona Sensors CD-1 ignition and locking the distributor and using the programmable ignition to handle the advance and idle control. I have a big cam boat with a carb and the idle control on the CD-1 is phenomenal. They also have a wiring diagram to use the existing Merc distributor. There are a lot of options for marine certified carbs, I prefer the Holley 4150 variety. I have a non-choke variety and I boat in very cold temperatures, with the idle control I don't need a choke. Most of the older BBC's are using the GEN 1 Merc water pump which can be bought with a mechanical fuel pump boss. It uses a different actuator arm than the block mounted pumps but you can find a mechanical pump pretty reasonable. When I started mine for the first time this year I had to run the starter for a bit to get the fuel through the filter and into the carb. Once the carb had fuel it fired right up and let it run at a high idle for a minute and I was good to go. Starts faster than my new Yukon Denali. I was thinking of going to an EFI system because I had such a hard time docking with an MSD ignition and my big cam. After running the CD-1, I really love my carb. I can idle down the river for an hour and it doesn't soot up my transom and I get great fuel economy. Something else to think about when selecting a carb, you can get Holley parts just about anywhere.

What did use for throttle linkage ?

Stock cable and You can find btacket, carb arm bushing, and bracket to cable mounting bracket (few styles you can choose) here, or other places of course:


https://www.hardin-marine.com/c-878-...-brackets.aspx