Is it a Rochester or a Mercarb?

[MTBoat]

I have a 1993 Mercruiser 5.0, Engine Serial Number OD829259. I can't find any numbers on my carb,,,SO,,,,,,,, I am trying to figure out which carburetor I have, since, they seem to show opposite ways of putting in the small fuel screen depending upon which carb it actually is.

My mechanic put it is according to the Mercarb exploeded view, and I had surging problems after running a bit, and finally bog down to nearly nothing....then I see a Rochester diagram and it shows it put in exactly opposite...WHAT!

Here is the link to the manual showing what I am talking about, https://web.statler.wvu.edu/~mathews/boat/pdf/manual/Chapter Eleven.PDF
if you go to Chapter 11 pg 292, it shows fuel screen and spring going in one way,,,,go to 308 and Rochester shows it exactly opposite...I AM SURE THIS MATTERS, and no forums and discussions ever seem to nail these two opposing processes or no one will state exactly which is right.

I figure if I have the Rochester, then that why its been surging and bogging down as the mechanics put it together the Mercarb direction....
Please help if you know, or can bring some clarity. (Also good to know which end of screen goes against spring in either case since one end is blocked solid plastic and one is open like a basket, and the unclear photos simply don't make that clear either and it is never discussed or explained that I can find......

Thanks

 

[jrs_diesel]

Looking up your serial number, you could have a Mercarb, Rochester, or a Weber.

The Rochester is a 4 barrel, the Mercarb and Weber are 2 barrel carbs. Post a picture of the carb and we can go from there to ID it.

As far as the filter, the opening of it usually faces the inlet (gas line), with the spring pushing against the solid part of the filter.

 

[alldodge]

I'm finding you should have the Merc 2 barrel carb. The Webar and Rochester are both 4 barrels
http://www.mercruiserparts.com/5-0l-2-bbl-gm-305-v-8-1988-1995-0b7

The carb on page 292 uses a filter stone and carb is a Rochester BC, Also note the fuel bowl is different then the 2GC


The carb on page 308 uses a paper filter and is a Rochester 2GC



Your carb uses a fuel strainer (part number 35-53336Q) and is installed like the paper filter in the 2GC
http://www.mercruiserparts.com/bam/subassembly/31835/1014/180

 

[MTBoat]

Thank you all very much.
All Dodge, I think you nailed it....it is a mercarb, and I failed to point out that page 309 showed the proper way to install, yet, my mechanicabsolutely installed it with the spring in the carb,,,and i am sure the solid end then, positioned wrongly, blocked the intake slot periodically under load and that would explain all of my problems,,,yet,,,,nearly everyone I asked also thought it should go that way.

And, you showed the right filter,,,it is a screen basket as pictured in your diagram.
You know, if you don't find some key point like this, you drive yourself and everyone else crazy, looking for ghost in fuel and spark- a dozen places each at least.
I'll be back if this does not fix it...but...I'll put my horse money on this one!

 

[achris]

Mercarb/Rochester. 1 idle mixture screw or 2?
1 screw = Mercarb
2 screws (1 for each barrel) = Rochester.

Chris.