Rochester Carb

[jrsick]

Has anyone replaced a Mercarb with a Rochester? My Mercarb is frozen and is beyond rebuilding. If you want to see pictures see "Shift Cable Frozen" thread in the Sport Boat section. I originally thought problem was the cable, but turned out to be carburetor throttle linkage.
I have placed 3 orders for a new Mercruiser carburetor from Summit, West Marine, and Marine Engines.com, and in each case received a call from the company stating they did not have the carb and don't expect to ever re-stock the item. I've searched ebay and craigslist for months with no luck.
A Rochester carb is available from several sites online. These carbs have an electric choke vice the fuel enrichment module that is on my current carb. I'll need to get 12vdc to the Rochester.

[mmwjr]

I would get an Edelbrock 1409 Marine carb. It’s 600 cfm, everyone who has switched to it loves it.

Don’t recall if it’s a spread or square bore but I think it may come either way or use an adapter.

[donald]

What carb do you have 2bl, 4bl
If it is a 2bl you will need to change the intake manifold to be able to use an Edelbrock marine 1409 carb.
Good luck with your search.
Don

[donald]

Adding 12 volts to the carb for the electric choke is not a big job.
Just find the 12 volt wire from your ignition switch and tap into that, the chock has 12 volts to it any time the ignition switch is on.
Don

[jrsick]

I have the 2bbl carb. There's a Edelbrock 1409 on local craigslist here. I may go take a look at it tomorrow and see how the bases match up, I don't want a new manifold.
Is my current carb a 600 CFM? I haven't been able to find the specs on it.

[donald]

A 1409 is a 4 bl carb, you will need to replace the manifold.
Don

[donald]

Try this
Summit Racing
Jet Performance 33007 carb part#33007 $409.00.
Electric choke, but like I said not a big problem and imo a lot better than a TKS carb.
Or try and rebuild yours.
Don

[donald]

600CFM would be a 4bl not a 2 bl.
Don

[mmwjr]

As Don stated the one I mentioned is a 4bbl. You can either change the intake or use an adapter, however the adapters I have seen have bolts inside the bores that if come loose will drop into the intake. That said I used one on a 4.3 in my 20’ Sea Ray for years with no issues, just use loctite on the threads. Note this will raise the carb a couple of inches.

Sierra sells rebuilt carbs and Holley make 2bbl marine ones.

[jrsick]

Thanks Don and Mike, I appreciate your great inputs.
I will first try to rebuild. Once I get it apart I will apply heat to break the throttle shaft free.
I was wrong about my CFM. I have a 2BBL and had heard it was 600, but its probably closer to 300. I don't want to go to a 4BBL because I doubt I'd ever get the mixture correct. Something about rich fuel mixture and boat engine that doesn't work for me.
I've ordered the rebuild kit. If rebuild goes well then I'll take the boat out on the first warm day we get. If rebuild goes poorly then I'll send box of parts to National Carb and let them fix it.
Mike, I couldn't find a Sierra carb that fit my boat, either new or rebuilt. My Sierra carb is 18-79994, and this part is not available as per the 2018 Sierra parts catalog. A lot of sites list the part, but when I call them they tell me it's not in stock and no estimated arrival date.

[mmwjr]

Be careful with using heat as you may damage the throttle plate shaft bushings. Try to find a carb soak solution so you can let it soak for a few hours to loosen things up

[donald]

+1 to what Mike said.
Heat may damage things.
Get some carb cleaner, a couple of cans of spray and a 1 gal can to let it soak in then spray after you get it apart.
Don

[jrsick]

Aren't the bushings brass? I expect to replace them anyway. Even if I did get the throttle to move I wouldn't trust it without new bushings.
I've soaked this carb in carb dip overnight. I've set it at every possible angle overnight while penetrating oil worked in. I've boiled it in simple green.
Bushing replacement means removing the butterflies. Nice winter project.

[donald]

Bushing may not be brass, maybe just base material of carb.
Don

[jparsons121]

My Mercarb didn't have bushings as Donald mentioned. I ran a reamer thru when cleaning to true up the bore on my rebuild. One note... Be sure to drill the crown off the backside of the butterfly plate screws. They are peened over a bit to keep them in place and will break off if you don't relieve the crown first

[mmwjr]

I have seen brass and nylon bushings. Housing is aluminum so you need to be careful not to distort it by using heat.