Saturday, March 14, 2020

Electric Choke Conversion

My old Holley Carburetor had an electric choke on it.  The "new" one had a manual choke. I didn't want to punch a new hole through a firewall and dash board to install a manual choke cable, so I bought a Holley 45-223 conversion kit.

First, you have to remove the old one.  The kit comes with instructions, but not a lot of pictures, so I got a bit stymied on a few things.  As you take the old one off, there are a few things you want to save (these are re-used on the new choke) :

  • The screw in the choke cam (mine did not have a spring, it was a plastic choke screw, so I used the marine screw provided and made the adjustment with that)
  • The clevis pin holding the manual choke mechanism to the choke rod (this is a tiny pin - don't lose it)
  • The fast idler cam screw

So, start by removing the three screws holding the mechanism to the carburetor body.

Next, remove the clevis pin holding the rod to the choke body.  Set this aside, as you will swear at me if you lose it.

Remove the fast idler cam screw, and set this aside, because you are going to need it later.

Remove the fast idler cam mechanism - it just slides away from the carburetor body.  While you have the cam mechanism, remove the screw adjuster and set this aside, too.

The manual choke housing is made of two plastic parts and some linkage.  You can either discard them or hang on to them if you ever want to change it back to manual, but please wait until the installation is complete before discarding anything.

Next, it's time to start the installation.  The kit comes with two square-looking cork gaskets with a hole in them.  The gaskets are not actually square - there is a ring cut into the cork - that is what you will need, and you need both of them.  Where the rear screw attached the old housing, there is a small port on the carburetor body.  This is the choke vacuum port.  Clean the surface on the carburetor.  Once clean, take one of those square cork "gaskets", and peal the backing off.  It should stick. Note, it could be so old that it doesn't - that's my experience.  I used an extremely small dab of grease to secure the gasket in place.

Next, install the cam - the instructions here are pretty good - you just need to remember to use the cam adjustment screw from the manual choke, along with the fast idler screw that holds it in place.  Follow the directions (they have three pictures in the instructions that show orientation and setup fairly well).  Then, install the fast idler screw to hold it to the fast idler shaft.  That is a rod with a slotted end to fit and lock it all in place, so make sure you get it seated properly.

Take the other gasket, and fix it to the back of the new electric choke hosing.  It took me a minute to find where it went, as I kept looking at the inside (the concave side).  You'll be looking at the side with the red plastic cam.  There are four "tubes" coming off on that side, three are for screws to attach it, and the other will have a little brass "bushing" inside with a very small hole.  That is where you'll put the second round, cork gasket.

Next, install the metal cam to the choke rod.  This takes three hands working with good coordination, or two hands if you want to cuss a little.  Once in position, attach the clevis pin from the original manual choke.

Now you can lift the red cam as you set the choke housing into place using the three screws to ensure the correct position.  When done, you should be able to move the choke in the carb and see things move in the choke housing (there's a little rod that sticks out from the housing).  Make sure the red cam is on top of the fast idler mechanism.  You may be able to reach behind the choke housing and wiggle the cam to ensure it is in a good spot.

Next, install the actual choke cover (the plastic piece that has the bi-metallic strip inside).  To do this, set aside the screws to hold the cover down within reach of where you are doing this, because you'll only have one hand.  Put the metal retaining clip (that has the three screw slots) over the outside of the cover with the concave side out (meaning the screw holes are going to be farther out than the edges in between).  Set the round gasket into place into the housing (it's easier than manipulating the retaining ring, cover, and the gasket while trying this.  That strip has a small ring on the end.  Here's some trickery, because as you install it, you have to get the bar sticking out of the housing into that ring.  I'd immediately (while holding the cover in place) grab one screw at a time and get it far enough in position (but not too tight) that it holds it all together.

You should still be able to turn the cover, and see the choke cover open/close (do both to make sure that strip and shaft are properly seated).  Once validated, turn the cover until the marks on top of the housing and the cover line up, then you can fine-tune the choke from there.  When "cold" (e.g. not having been connected to the battery for a few hours or so), you want the choke plate to be barely open (a #2 pencil is what Holley recommends as the starting point).  Then, tighten the cover screws until you can't turn the cover.

Now, you can do the electronics.  I ran the negative side to one of the carburetor bolts.  The other one (the red one) should NOT get attached directly to the battery (or any other always-on connection), as that will completely negate the choke and drain your battery.  You want to tie it to an on/run wire so that it is only at 12 volts when you are running the car.  As soon as you turn the key to the on position, the strip will start heating up and open the choke plate.  It doesn't matter if you actually DID start the car, it's going to start moving.

No comments:

Post a Comment