Ron, I hear ya bro, But it will have to wait until next year
I have spent so much loot on this boat this year im beyond tapped.
I even spent my school tax money (I did not know that at the time though)
I wish I could toss 2 holleys on there and be done with it but I cant.
From what I was told before when I asked this on the board, I was informed that the 454-330 HP engines came with 750 Rochesters on them
not 600's
And of course it is not stamped on the side in a yellow sign hey dude im a 600 or 750 or anything either (thanks alot rochester yeah 3 thumbs up there buddies)

Anyway, Im going to call the engine builder soon around 1030 - 1045 ish and see what he has come up with
If I need longer metering rods and stuff that is fine I just need these rochesters to last me till end of this year
I can get 2 holley's over the winter time used or what not.
I see 2 on the classified section for 500 a pair which is a good deal assuming they dont need rebuilding.
I will in no way put car carbs on this thing. I agree with you there too dangerous
Hell I found a carb to air cleaner gasket on a friends boat, took that off and smelled it before throwing it away and he was like WTF you doing,
Ahhh nothing just saving you from blowing yourself up thats all

I dont play around with safety issues in a engine compartment, I might cheeze out on a few things but safety is not one of them.
If something safety prevented me from going out this year then so be it, I would be alive next year to go boating
Nuff said
Jason

simple calculation tells you this carb will not work!...toss them now! make them someone elses problem. save a ton of time and frustration...even money in the long run...go buy a holly...far less trouble...i may have a set for ya next week, by the way

but first troubleshoot the ROOT cause! why buy carbs if the engine is........

I hear you Jay. Ive been there too bro. Back to the carb. If the carb has the two large spring loaded screws on the front of the carb near the base plate it is a WFB not a Rochester. The Rochester is a GM Quadrajet. They can be tuned also but not to the same degree as a AFB or Holley.

You need to find out what you have. Are the front and rear barrels the same size or are the back ones larger? If the back ones are larger then you have a Quadrajet (spread bore). I had a 1995 330 merc and it had the WFB carb on it 600 cfm. I think you have the WFB, (weber four barrel), the same as the Carter AFB, also the same as the Edelbrock Four Barrel, and 600 cfm.

Find out what you have then find someone who knows how to tune it. This is the cheapest way out. You say the engine is popping under a load and is running higher oil temps than normal. These are signs of a lean condition. Now Audacity being the engineer he is will tell you to check several other things which is correct. Ill leave all the details up to him. He seems to know his stuff.

The ideal thing would be to find a good carb guy. This guy will ask you all the specifics on your engine componets then compare that to a log book he keeps on carb settings and come up with a setting that will be close. Then if you like you can fine tune from there.

Keep the faith bro, your not done yet. When you modify an engine you become the engineer that designed the package! You are now responsible for making the engine run in a real world enviroment in all kinds of conditions.

Ron

Another thing comes to mind in determining which carb you have. GM went to all fuel injection around 1987. Because of this they stopped making Quadrajets along with all carbs. This is when Mercruiser went to the WFB carb because the Quadrajet was no longer available.

Oh and I second Audacity on the root cause. Keep this engine builder around until you make sure the problem is the carb and not him.

Ron

Well it is a spread bore and does say quadrajet on the side of the body so im inclined to say that it is a rochester
That being said I was told it was a 750 from board members.
Let me call engine dude and see what is going on over there and if there are any suggestions or ideas or someone else going to get involved or what not.
I do have the gasket and adapter plate for a square bore carb for my spread bore intake manifolds (came with the new intakes) so Ill be good there if I do switch to holley's or whatever
Jason

Yep, its a Quadrajunk I mean Quadrejet. Disreguard everything I told you about the AFB. The only thing I ever did with a Quadrajet was replace it with a Holley.

More bad news. If you have spread bore manifolds that will require an adapter to run a square bore carb you will need to buy new manifolds if you go with the Holleys later. The adapters are junk and have no place on a performance engine. Holley does make a spread bore carb thats great and it fits on a spread bore manifold but I dont think they make it in a marine carb. A lot of aftermarket manifolds such as Edelbrock come drilled for both a spread bore and a square bore carb and both can be used without an adapter.

What intakes are you running?

Ron

Edelbrock performers polished and it did come with a plate and a gasket for square
Jason

Jay,

Went through somthing similar a few years back when I swapped a 454 for a 502. Tried to scare up all the parts for the Q-Jet. Never did run the Q-Jet but I did get all the rods, hangers, jets from the link I posted above. I used the specs from a 502 mag from around 90 or 91. This should be plenty of fuel or at least a hell of a lot more that the stock 330 carb. I don't know where I put those specs but if you are interested Tom S. (Budman) has all the carb parts I ordered. He put them on a stout 454 with about 224/236, around 9.0 to 1, 30 over? and runs just fine. No signs of lean. PM or e-mail if you want the part numbers etc.

Tim T.

Jay,

Now that you have determined you have q-jet carbs do this now ! Go to your nearest Chevy dealer & get 4 secondary metering rods part # 7046010, size .0440 . They may not be the exact ones you need but they will richen up your fuel flow & put you in the ball park. They should cost about $30.00 for all of them. You can install them yourself in 10 minutes. Take off your air filters and using a #9 torx head screw driver remove the small screw on the secondary mounting rod hanger. This is right behind the threaded rod that the air cleaner bolts down on. Be careful not to drop the screw in the carb. Lift the rod hanger up & the metering rods come up with it. Slide the old metering rods off to either side, put the new ones on & reinstall. It's that simple, no big deal. You will feel the difference when you run the engines. If it still feels lean, popping, backfiring, hesitates or feels lazy when giving it gas you may have to richen it up more. These carbs will flow 750 cfm, plenty for your application, and work great when dialed in. Don't go the adapter, spacer, new carbs, route, you'll just have to rejet & dial in the new carbs any way and they probably won't work as good as the q-jets. Good luck !!


Bo knows

Jay, throw away the Quadrajets and get a pair of 9381 Holley`s. They are 830 cfm annular discharge double pumpers. You can usually find them at a real geed price from Jegs. You should be able to bolt these on and the jetting will be very close if not perfect.

I have had these on many boats with similar set up as yours, they work incredibly well.