Thursday, November 8, 2012

Carb Rebuild

   While my boat runs and can get you across the lake I would not say that it runs like a top.  I know that the secondaries were not opening during my test run with the boat so I will start my diagnosis by rebuilding the carburetor   Now, I would not be surprised if there are more problems with the engine such as the timing or the spark plugs.  Unfortunately I do not have much access to a lake right now I will only work on this right now.
   The PCM 351 is fitted with a Holley 1460 4 barrel carb.  It has vacuum secondaries and an electric choke.  I suspect that there is a blockage in the vacuum tubes that operate the secondaries.  Cleaning the carb is pretty straight forward.  You simply buy a rebuild kit and a good amount of carb cleaner.  The rebuild kit should come with new gaskets, needles, power valve, accelerator pump and many other parts that wear out. The general steps for rebuilding a carb are:
           1.) Disassemble
           2.) Clean
           3.) Reassemble
An exploded view of the carb comes with the kit and is pretty easy to follow.  There are some detailed guides for rebuilding on the internet and these are a few of the ones I used.

   There is only one special tool that is needed.  On the metering block there are screws that look like phillips heads but are a little off.  I forget the technical name for the bit you need but it is possible to grind down a phillips bit as an alternative.  Be very careful with this and you can do it with out stripping the screw but if you grind too little or too much and are careless then you will strip the screw.  You will also need a stand for the carb so that you do not bend the throttle linkage: a simple wooden block can work for this.
   This is a pretty simple thing to do and can help your boat get closer to running like a top.  I have a few tips for you.

  • Do not cut your hands while getting the carb off the boat.  I nicked a knuckle and learned the hard way that cuts and carb cleaner are not a good combination.   
  • Soak the parks for at least 24 hours.  Giving the parts plenty of time to soak insures that all the passageways get cleared out.  You don't want to get out on the lake and realise that the carb is still gummed up.
  • Be careful lining up the gaskets.  You do not want an air leak in your carb.

   Many people see a carb rebuild as a difficult and scary procedure but it is really not that hard.  It can easily be done in two evenings with a minimal amount of tools and mechanical know how.  If you are having carb trouble I suggest that you give a rebuild a try rather than spending 5 times as much having a marina do it.

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