Carb removal fears! Any alternative??

[porro]

This spring, my A4 (1975) will no longer idle. 3/4 choke will enable slightly lower RPM's but any further throttle reduction produces a swift shutdown. Starting is accomplished with full choke and above normal throttle position.
Perusing the forums and looking at the MMI Service manual indicates a high probability of a restriction in the idle jet or idle passageways of the carb. The remedy given is to disassemble and clean the carb.
My 1975 Catalina 27, however, has horrible access to the carburetor side of the engine, restricted by the floor, wall, and corner of the port locker. It took agonizing head-down contortion just to try to manipulate the idle adjust screw (no effect on idle, by the way). I consider the disassembly of a carburetor already pretty challenging but trying to remove it from and return it to the engine on this boat, including detaching the various items necessary, seems like a high risk enterprise, considering its location. I doubt whether the carb has ever been removed.
Do I have any hope of a short cut, considering the above described symptoms, i.e. partial removal, feeding Gumout, blasting with pressure, some miracle carb cleaner, etc., etc.? Below is recent history, just in case it's relevant:
a) Prior to fall haulout, wouldn't start. Switched to portable tank to provide certain clean gasoline. Turned out to be rust-thru pinhole in sediment bowl, which I replaced. That fixed the problem. I kept the portable tank and used it with new gas this spring, thinking that I'd try to figure out how to flush out my 32 year old gas tank this spring.

[tenders]

If it's any consolation, once you get it off, the rebuilding of the carb is very easy. There are so few parts in it that I was surprised the carburetor does anything at all.

I have the same idling problem this spring, but I'm pretty sure it's because I'm still drawing down last season's gas. Are you SURE your fuel is fresh?

[Don Moyer]

Fortunately, your research seems to have very professionally ferreted out the most likely cause of your engine's refusal to idle. Unfortunately, I can't think of a way to spirit inside your carburetor and open up the idle passageways without removing it from the engine. You can certainly try some heavy-duty solvent to dissolve the blockage, but it will have to be a solvent that you add to the gasoline (preferably right at the carburetor), since spraying it into the air stream entering the carburetor won't get to the itch you're trying to scratch.

Don

[marthur]

Your 75 C-27 is probably set up exactly like my 77 C-27, and this is not a job to worry about. While a little tight, it is not a bad job from the FRONT of the engine.

If it will help, here is a step by step for removing the carb:

First, remove the door to your engine compartment. You want to work from the front and the few inches this gains is more than worth while.

Second, remove the choke cable and throttle cable. These will not be hard to reach from the front. They will be almost impossible from the port locker. Be careful not to drop the clevis pin or washer!

Next place rags or absorbent pads under the carb to catch any gas that leaks out and remove the gas line. This one is a little more difficult to see from the front, but it is not overly difficult to reach. If you have the PCV valve upgrade, remove it now.

At this stage, I usually remove the flame arrester, because it makes the carb a little easier to maneuver. Even if you choose not to do so, you will be able to get it out. When putting it back in, however, install the flame arrestor last.

Now to remove the carb all you need to do is to loosen the two nuts that attach it to the intake manifold. When those are off it will practically fall into your hands.

Installation is just the reverse.

When you have the carb off disassembly and cleaning are a snap. Here is a link to pictures I took of that job on mine:

http://home.earthlink.net/~ultratom/carb_site/atomic_4_carb_rebuild.htm

Good Luck!

ma

[porro]

Re: carb fears

Thanks guys for the reassurances and also the instructions. I'll let you know how things are going. Don, thanks for using the word professional. By the time I'm face to face with the carb, I'm sure the good feeling I have right now will revert to "amateur" quickly.
porro

[porro]

Carb removal - fear no more!

I have successfully removed, cleaned, and reinstalled the particular carb which was not able to idle. I'm glad to report the process was successful. Thanks to marthur for the photo sequence showing disassembly and Don for the confirmation of the probable passageway clogs.
Although nothing was obvious, a blockage or constriction had to be present since I made no other adjustments but the engine idled very well upon completion. I did not, however, remove the main idle jet when dismantling but did replace the main gasket and the flange gasket.
I was confused for awhile about the small triangular shaped pin which is controlled by the float and which presumably regulates the passage of gas into the float chamber. It fell out while I was dismantling the carb and I was unsure about which end went back into the passageway. I assumed it should be the pointy one and, on close examination, that point turned out to be made out of a soft material. When placed back into the passage, the pin seemed to stick and the carb had to be jiggled a bit in order to get the pin to drop onto the float. I now assume that the rubbery point just sticks in the opening briefly and that this would not happen when fuel is actually flowing in the carb. I also assume that the material is necessary to make a tighter seal and prevent excess fuel from flowing into a full float chamber. In any case, I did not see any descriptions of this pin anywhere but sense that I put it back in its proper orientation.

[Don Moyer]

Your understanding of the needle of the float valve is 100% correct.

Don