In the process of a carb rebuild, but now stuck
 

Hi everyone, I have a 94 4.3lx with a 4 barrel carb and Im in the process rebuilding the carb but now im stuck. I removed all of the 8 screws on top of the carb and I can not separate the top and bottom half! I then took a small putty knife and gently pushed it in all the sides to try and free the gasket as much as I could. When I try to lift up with the knife it feels like something is still holding it back. Did I miss a screw or something? I looked it over but cant see anything else holding it. Thanks!

carb rebuild
 

Do you Know the make and model of the carb? Can you post a picture of it?

Is there a long stud in the carb for the spark arrestor? If so, try removing it.

Thats it!! That one stupid stud was holding it. It would have been nice if the merc manual said to remove that lol. Thanks again

Your welcome.I'm pretty good at taking stuff apart. Putting it back together? Well...

I am like that also because most of the time I cant finish it all at once and then when I find time to complete it I forgot how to put it back together lol. Have you ever done metering rods for this weber carb? Just wondering if I got the metering kit from mercruiser if it was just something I plopped in or do I have to do adjustments? Thanks again!

I'm not familiar with your particular carb/application.

Generally speaking unless there is a compelling reason to change the metering rods it is likely they are fine for re-use when doing a basic rebuild.

There are folks on this site who know a lot more than I on this subject. Some of them are in the business of marine repair and could do the rebuild for you.

Whatever you do, when you re-install the carb on the motor CLOSELY check for fuel leaks. Then do it again. And again!

fixx
 

leave them alone..the only tip i can give you is to remove the little screens on the needle and seats and pitch them..they clog easy and will give you trouble down the water...

Thanks for the tips! I think for now I will leave them alone and if I still have trouble with the carb then ill have to do it. I know the one rod is worn diameter wise but the actually length is fine.

The diameter of metering rods where they travel through the metering jets is seriously important. Being of the correct length is virtually of no importance.

I mean no fowl, but perhaps this job should be turned over to someone who has experience rebuilding carbs. I admire your desire to pull your own wrenches, but I'm not sure this project is a good one for you at this time. If it is not rebuilt correctly, it will drive even the best of us crazy trying to get the boat to run correctly. And, finding a mechanic who will accept responcibility for correcting an a previously unsuccessful rebuild may be a challenge.

I have done carb rebuilds in the past so doing the rebuild is nothing new to me. I haven't dealt with metering rods before though. I rebuild my whole sterndrive so I am mechanically inclined. At this point im going to leave the metering rods alone and just do the rebuild and see how it runs. If it still runs rough then ill have to do the rods. Thanks for all the help everyone!

If you were able to visually spot the difference in metering rod diameter where they pass through their respective jets I would seriously consider replacing the rods. Same goes for their jets if they are removable.

From the sound of things here, I think we are talking about a Rochester Quadrajet carb. The primary and secondary metering rods on these carbs almost never "wear out". If they do, then something is seriously wrong. They don't really make much contact at all with the jets that they ride in - it is more of a situation of restricting an orifice rather than completely closing it off, if you look closely at the operation. Many of these rods are intentionally stepped, which could be confused with wear. Unless you have made major changes to the operating characteristics of the engine, i.e., displacement, cam timing, much better heads, then there should be no need to change jets or metering rods. I would simply go with a good MARINE grade rebuild kit, thoroughly clean it in carb cleaner and blow out all the passages, and reassemble it according to the directions in the kit. Keep a close watch on the float adjustment, because they are quite sensitive in this area, and unlike a Holley, you cannot change the float setting without taking the main airhorn (top) off of the carb.

If it was idling rough and running rich at idle and low speeds, and you have changed to a cam that doesn't draw as much idle vacuum as the stock cam, then it is possible that you need to change to a lighter (i.e. weaker) main power valve spring. This is the spring that rides under the plunger / hanger that holds the primary metering rods. It is pulled down by idle vacuum to hold the primary metering rods down (closed). If there is low idle vacuum, then it will not be able to overcome the spring that is forcing the rods up off of the jets. Changing the rods or the jets will have little if any effect in fixing the rich condition if this is the case.

Good luck!

Thanks for all the info! Im pretty sure I have a weber 4 barrel carb though. It was actually starving for fuel because if I put the choke on my rough idling would clear up. Is weber more sensitive with the rods? I have some pics of the carb below. Thanks again

when you shut the choke whyle the engine is running and it still runs you have a vacume leak,the engine should die...

And that is a webber carb .......

I thought it was a webber because when I enter my serial# for the parts catalog from mercruiser it showed 4 barrel as webber and I believe the 2 barrel was Rochester. I dont remember if I closed the choke completely or just part way. If I did close it fully then ill check into the vacuum leak issue. Is there a common spot for a leak on this engine? Thanks!

fixx
 

intake gasket,,if the bolts are loose then suspect the intake gaskets..

Ill have to take a look at the bolts and see if there loose. Thanks

I finished the rebuild over a week ago and all is good. Thanks for all the help! It has slight bucking at around 3000 rpm but I need to replace the cap, roter, and wires + plugs, so hopefully that will help. If not ill have to do the metering rods.

I'm glad it worked out well. Thanks for the update...not everyone closes the loop with people who reply to their posts.

Carb manufacturer
 

Looks like a Carter AFB to me,similiar to the carbs used on361 and 383 Mopars from the early 1960's.