1972 Sea Ray Mercruiser 165. Rochester Carb

[Ike]

The saga continues. The Sea Ray has been in the water all summer. I had an issue with water in the oil about three weeks ago. It was a leaking gasket between the manifold and the riser. Got that fixed. Overall it runs well. I go fishing every few days but don't run it hard. I had it out several times just to open it up and see how it is doing. It still has the stumble problem. At about 1000 rpm it stumbles and stalls. I can work the throttle and get it past that. I have talked to a lot of people and it seems to be the consensus that it's the acceleration pump.

Anyone here familiar with the Rochester 2GC and 2GV carbs. Just to recap. The boat is a 1972 Sea Ray 190 SRV (18 ft) I/O. It has a Mercruiser 165 (GM250) with a Rochester carb. It was rebuilt in 2013. However, although it runs fine at most speeds, at about 1000 rpm it stumbles and dies, unless I play with the throttle. Above 1000 rpm it runs great and goes up to WOT at about 4000 rpm (30-35 mph by the tach and speedo. Never checked it on GPS) Is there an easy way to adjust this? The Mercruiser manual is about as clear as mud. Or. should I just get a new carb? If so what model?

 

[PAR]

You might just need a check ball. The 2G can have one or two. The big one (steel) is in the main discharge tube, while a smaller aluminum ball, is usually at the bottom of the accelerator pump cylinder. The 2G's that don't have the accelerator pump check ball will only have a single hole at the bottom of the accelerator pump cylinder. The bottom of the pump will be smooth in these versions, while the ones with the check ball will have a little concave depression over a hole, sometimes two holes (one is off to the side of the pump bore).

In all honesty, you should just rebuild the accelerator pump, with a new plunger, discharge "T" and retainer clip. Check the carb carefully at the bottom of the pump well for the dimple and hole count, as this is a common mistake by rebuilders, putting a ball, where one shouldn't be. Maybe just spring for a good rebuild kit, which will have the accelerator plunger in it.

Eventually all carbs just can't be rebuilt any more and have to have a replacement body. Reman units for this carb are about $200 - $250.

 

[Ike]

Eventually all carbs just can't be rebuilt any more

That's why I think this one may have reached it's end of life. I had it rebuilt last year and they did a great job, but who knos how any times it has been rebuilt? It's 42 years old.

If I were to put a new, new, carb on this engine, what would you recommend?

 

[PAR]

They still make the 2G series, though I'm pretty sure it's an Edelbrook unit now. Using the same carb means everything is a bolt on swap, no linkage issues, choke, etc.

 

[Ike]

I'll look into that. It would make it easier to put on a new one.

Some of these boats came with Holleys. But apparently the models used are not made any more.

 

[PAR]

There are a lot of 300 to 350 CFM carbs that will work, though mounting flange differences can cause issues, plus linkages, which is why I recommend simply another 2G.

 

[Ike]

You're right. I have been looking at carbs on-line and there are some drop in replacements that look exactly like the 2G

 

[PAR]

Summit Racing sells a reman replacement for the marine 2G and it looks like it has the Volvo or Mercruiser linkage on it. It's about $300.

 

[Ike]

That's one of the carbs I was looking at. I have bought from Summit racing before and they have always been a reliable source. Plus that, when I need to return or exchange they have always done it without any problems.

 

[PAR]

I use both Summit and JEG's fairly regularly. JEG's usually has slightly better pricing, so check them too.

 

[Ike]

Thanks for the tip about JEG. I looked at their web site. Looks like a good source.

 

[PAR]

I just received a duel quad tunnel ram from them. Now, I got to buff the crap out of it. It might have been worth the $100 extra bucks, to have them supply it polished.