Carburetor HELP!!!!!

[trainwrecker22]

I repowered my boat and went from a 5.0L (305) to a 5.7L (350) I had a timming issue so I thought but turns out to be a carb issue. I only have a 2 barrel on her and it just is not enough for the new engine. I procured a Quadrajet (Rochester) from my uncles boat he had sitting out behind his barn. It is a early to mid 80's boat. I am curious if I can put this carb on my merc also could use some help locating a rebuild kit for it. I have no info for the carb but will post pics. I am also going to need a new intake as the one on my boat is a 2 barrel. I honestly dont know that much about boats so any help would be appreciated. I am attaching pics of my carb and the qudrajet. also the info on my boat is it is a '95 merc 5.7L OF358602.....well I cant seem to attach pics but if some are needed i will figure out a way

 

[alldodge]

I repowered my boat and went from a 5.0L (305) to a 5.7L (350) I had a timming issue so I thought but turns out to be a carb issue. I only have a 2 barrel on her and it just is not enough for the new engine. I procured a Quadrajet (Rochester) from my uncles boat he had sitting out behind his barn. It is a early to mid 80's boat. I am curious if I can put this carb on my merc also could use some help locating a rebuild kit for it. I have no info for the carb but will post pics. I am also going to need a new intake as the one on my boat is a 2 barrel. I honestly dont know that much about boats so any help would be appreciated. I am attaching pics of my carb and the qudrajet. also the info on my boat is it is a '95 merc 5.7L OF358602.....well I cant seem to attach pics but if some are needed i will figure out a way

:welcome: to iboats

The Rochester carbs are pretty good ones. Doesn't take a lot to rebuild (if they are not to worn out) and work great. Look on the side of the carb and there should be some numbers going up one of the corners. So far as posting pics, use something like photobucket and they will work out.

 

[Walt T]

Chances are the original 2 bbl supplies more than enough cfm for the engine. First off get the number off both carburetors so you at least know what you're dealing with. QJet kits are easy to come by. So are 2 bbl kits. What are your symptoms? I have seen it thousands of times... Carburetors get blamed, overhauled, problem still exists, carburetor must be bad! Replace it, still has problem after lots of money and time. Not saying you don't need a carburetor, just saying you need to be better informed and so do we in order to help you.
Once had a customer bring in a boat totally frustrated that he had spent 1200.00 more or less I think it was at a shop and his boat was running worse. I asked to see the repair orders so I could maybe see what the techs had done. No work orders. OOoookay.
"Well what did they tell you?"
"Uhh something about a distributor first"
"Did they replace it?"
"Yep said it was worn out"
"Make any difference?"
"Nope"
"Do you always make it like pulling teeth to get information out of you?"
"Well they said all kinds of stuff but hell I'm not a freakin mechanic, Heck I doubt they were either"
"Okay so then what?"
"Well they said a carburetor or something must be bad and I asked them to put the old distributor back in but they said it was bad too but we just didn't know it. Then this guy come out of the shop and I immediately saw that the shop didn't offer a dental plan, and apparently didn't supply uniforms since this guy had pants around his knees, hat on backwards, and a tattoo that I swear was a picture of my ex wife which scared the hell outta me because she is one psychotic crazy train engineer but anyway he looked at me with the lazy eye off to the right when the boss yelled at him to show a little respect and turn the hat around which is when I saw he had 3 fingers missing two on one hand 1 on the other, he saw me staring and with that crazy eye and 4 tooth grin looks at me and says 'a couple of prop accidents' to which I didn't bother asking how he stuck his hands into moving props not once, but twice. I was feeling a little woozy so I asked to use the restroom and they pointed across the shop but said I couldn't use it since customers weren't allowed in the shop area, Insurance regulations you know, but judging by the condition of the place I doubted they had insurance so I told them to fix the carburetor and got the heck out"
"But.... after all that why did you leave your boat there?"
"Oh they seemed trustworthy"

 

[midcarolina]

I agree the 2 barrel is big enough........Is it a mercarb 2 barrel? Since you are thinking it's not enough carb I assume your issue is at wot,
I would check fuel pressure first, also check that the choke plate is opening properly.....Have you changed all the fuel filters? including the screw in one at the fuel inlet on carb?

If you just want to upgrade to a four barrel thats cool too........ your motor should be a vortec make sure you get a vortec intake....old style will not work.

Go here for carb parts,,,,

 

[trainwrecker22]

wow I can not believe the responses! Thank you! I Do not have the numbers off the carb yet but will post them when I do. I purchased the boat thinking I was getting a great deal. Long story short I got a lemon. guy put gear oil in the crank so when we tested it for about 30 mins it ran like a champ. took it out for a few hours and lower end was gone. I got a 350 from michigan motorz. (replacing the 305 5.0L). I got it all back together and fired her up set timing and during the break in I could not get it to 3000 rpm's. it starts backfiring through the carb. If i come off the throttle a bit she smooths right out. This is in neutral. I put it under load it falls on its face and backfires up through the carb bad. I have pulled the plugs and they looked white from burning lean. I have put new filters on it, and before the old 305 let loose she ran great, ever since going to the bigger engine I have had nothing but issues, even though its the same block.
http://i180.photobucket.com/albums/x122/trainwrecker22/Mobile Uploads/20140816_115427.jpg
http://i180.photobucket.com/albums/x122/trainwrecker22/Mobile Uploads/20140816_1154440.jpg
these are links to pics of the carb

 

[NHGuy]

You might be having trouble with the 305 carburetor being unable to feed the 350 at higher engine speeds. The Mercarbs have replaceable venturi clusters I believe. They do what jets do on other carbs.
But also you could very easily have a fuel supply issue. Sounds like it's a lean pop. Since the boat is unknown pull all (I'd expect 2) fuel filters and dump the big one in a glass jar to check for debris and water. Remove the anti siphon valve at the tank outlet and poke a plastic stick in the tank end to make sure the little restrictor ball moves against it's spring. And spray it out good with carb cleaner. While the fuel line is off the tank take it off the pump and shoot some carb cleaner and air through the line too.
You can replace or repair the carb, sure. But I'd be darn sure it's getting enough fuel.

 

[alldodge]

wow I can not believe the responses! Thank you! I Do not have the numbers off the carb yet but will post them when I do. I purchased the boat thinking I was getting a great deal. Long story short I got a lemon. guy put gear oil in the crank so when we tested it for about 30 mins it ran like a champ. took it out for a few hours and lower end was gone. I got a 350 from michigan motorz. (replacing the 305 5.0L). I got it all back together and fired her up set timing and during the break in I could not get it to 3000 rpm's. it starts backfiring through the carb. If i come off the throttle a bit she smooths right out. This is in neutral. I put it under load it falls on its face and backfires up through the carb bad. I have pulled the plugs and they looked white from burning lean. I have put new filters on it, and before the old 305 let loose she ran great, ever since going to the bigger engine I have had nothing but issues, even though its the same block.

these are links to pics of the carb

Your running way to lean. The pics look like a Merc 2brl carb and as NHGuy mentioned it could be re-jetted but the 4drl sounds like a better option. Don't keep running it lean, your spitting pieces of your engine out the exhaust

 

[midcarolina]

What you are describing in post #5 sounds to me like you have a couple plug wires crossed up.......... I would double check and be sure, That mercarb should work fine well past the 3k mark. IF it runs lean it would be at the top of the rpm range...........unless the carb is screwed

 

[trainwrecker22]

Again thank you for all the help. I double, tripile, quadrupal checked timming and firing order. I just ordered the rebuild kit for the quadrajet (Thank you Mike).....now intake. This is what I am looking at http://www.michiganmotorz.com/edelbrock-marine-262400-performer-intake-manifold-198795-p-3262.html I am not sure what I am going to need to adapt the throttle linkage and ****. I hate to do this but any suggestions on where to find a used one cheap and maybe one I can get the brackets and what not off of, or will this one do from michigan motorz do? Is their a boat salvage yard I can contact or someplace that will have the parts I need? I am green as baby **** when it comes to boating.

 

[NHGuy]

Just get a square bore intake for the heads you have or get the manifold and brackets off your uncles boat. If you decide to get an intake they are differentiated by how many bolts they have, you can have an 8 or 12 bolt style manifold. The brackets go on the carburetor so get the ones off the old boat. You should not need to be concerned about manifold mount points unless you want to keep an old style heat choke. Marine isn't special, unless you are in salt water in which case don't get aluminum. If your uncles boat has the wrong style manfold you can still use the carb and carb brackets.
If the Qjet has a heat choke, (some call it a stove choke or a divorced choke), it will need a manifold with an exhaust heat passage to sit upon. If you don't want to mess with old tech you can even upgrade a heat choke to electric, you might be able to steal the electric one off the carb in your picture. Just be sure not to create any air passages when you bolt it to your carb.
Another really good place to get quadrajet parts and help is Cliff's High Performance. He has all the parts and the knowledge, you can call him or ask him questions on his forum. I used his qjet book and bought stuff from him, my engine runs great and It's really cause of Cliff.

 

[73Steury]

If your boat is raw water cooled in salt water you should look at this Edelbrock manifold http://www.edelbrock.com/automotive/mc/manifolds/marine.shtml. It's made for this application with brass in the water jackets.