I rebuilt my mercruiser/rochester now I'm more confused?

[riskibusiness]

First off I will say I know this topic has been beat to death. I did the rebuild and carb runs great. But I have rebuilt many auto carbs and I thought that somewhere during the rebuild I would have that AH HA moment where I would see the difference in the marine and auto carb. What is the exact difference. Because it seemed the same. BTW I'm not trying to find a way to put an auto carb on my boat(don't like fire) Just trying to educate myself. Oh and I have the 2 jet version on a 470 170 hp

 

[achris]

Re: I rebuilt my mercruiser/rochester now I'm more confused?

A few differences.
1. no vacuum port for a distributor vacuum advance.
2. the float chamber is vented internally, not externally like a car.
3. a tube going to the venturi for connection to the hose from the backside of the fuel pump diaphragm.
4. larger accelerator pump volume.
5. no fast idle cam.
6. threaded fuel inlet line. (Car carbs often have just a barb for rubber hose)

HTH,

Chris.....

 

[dan t.]

Re: I rebuilt my mercruiser/rochester now I'm more confused?

Well Chris makes some valid points but not all are correct.
1. a vacuume port makes no difference, it can be plugged
2.All 2bbl rochesters vent into the carb throat, a very few automotive also have an external vent

3. The vent tube can be put into the spark arrestor ( volvo penta)
6. all rochester carb inlets are threaded, some Holleys and Edelbrocks have hose barbs but can be changed to threaded.

 

[riskibusiness]

Re: I rebuilt my mercruiser/rochester now I'm more confused?

I knew about the fast idle cam but i didn't even notice it didn't have a vacuum port. That's kinda funny something you just don't notice during a rebuild