Carb Rebuild – What a Tale!
by Al Stoller
Where to begin! As with any project, there was a problem to be solved. Previous attempts using professionals had failed and I had a sense that if I did not do it myself, it would not get done properly. I own a 1964 Ford Corsair with the 1498 in line 4 cylinder engine with a Zenith VN33 Type 2 carburetor. The car was running badly, as anyone at the various gatherings we have attended will attest to. Lots of advise was given and different ideas attempted with little or no success. The carburetor was even shipped to a professional in Toronto to be rebuilt. After all that, the carburetor itself may have been fine, but the car still started and ran badly. Four different mechanics had also tried and failed to sort out the problems; the distributer and vacuum lines were examined and were fine. I decided that I had to rise to the challenge and try myself. This after approximately five years of muddling around. I had absolutely no experience and no clue as to how to go about the task. After all, I am not a mechanic and have no training, but when you own a vintage car you have to be willing to learn a lot and ask a lot of questions. I am sure that some people were getting fed up with me going on about the same topic.
And so I began. I first found and bought a carburetor through E-bay. The idea was that I would rebuild the second unit while at least leaving the original in place and using it for comparison purposes. The E-bay unit was advertized as a scrap unit, but these Zeniths are rare, so I bought it. Upon receiving the package, I compared the new unit to the one on the car, and it seemed as though everything was there. This particular design looked so complicated and I wondered if I had not indeed bitten off too much. Finally, I had experienced enough rough rides and embarrassing stall situations in the middle of intersections. The final straw came when I took the car to a mechanic who was supposedly an ‘Expert on British Cars’ and after parting with over $730, had a car that could hardly be driven. So, with all that in the back of my mind, I started on the job.
My first job was to go to the internet and find a schematic and exploded view of the components of this model carburetor. I also located a kit for this model and had that shipped to me. Once all this was done, I took the printed copy of the schematic to a printing company and had it enlarged to the largest size I could practically manage, and then had two copies made. One copy was going to be used to place and identify all the different components and parts that came off the carburetor and the other would remain clean and unmarked and act as my master reference. I then digitally photographed the original carburetor still in place and operational, on the engine itself, from any angle I could.
I then started removing the first parts and did this aspect of the job in a small cardboard box or bucket. This was based on advice from mechanics who told me that little tiny parts have a habit of flying unexpectedly off the unit and going where they would never be found again.
This trick worked a couple of times and I am glad I did this as it saved my hide. As each part came off, it was examined and then cleaned. Then it was gently scotch taped to its relevant position on the schematic or blowup view sheet. My lovely wife Judi was admonished to please not touch anything on that table in our small garage and thankfully, she cooperated fully. The Ebay unit was rather dirty and grimy, and so using a soft wire wheel, and/or fine, usually 200 grain, sandpaper, I cleaned off the different parts.
The next matter to be dealt with was the main body of the carburetor itself. It had a horrible amount of residue down in the throat and in some of the more inaccessible corners, and this scale and residue had to be cleaned off. Based on excellent advice, I decided not to try and sand the deposits off, but to use an ultrasonic cleaner. Fortunately for me, one of my work colleagues had one and loaned it to me. I used Seafoam and water initially for the solution and then ran the cleaner numerous times. It was neat watching the wave motion as the vibrator pulsated the solution, and the heater inside worked very well too. After several days of this, I decided to empty the cleaner and the color of the solution draining out was horrible. That carburetor had more grunge in it than I realized. I repeated this process twice more, taking about a week to fully clean out the main body of the Zenith. I also went through 12 bottles of Seafoam and finally, did not even bother mixing the solution. I gently cleaned the exterior of the carburetor with a product called “Nevr Dull!” Finally, the carburetor looked clean and shiny down through the throat area and while there was a small shadow of discoloration, the unit felt smooth and clean to the touch. With the main body and float chamber parts cleaned out, the other parts cleaned off thoroughly. With the carburetor kit ready to hand, the scene was set for reassembly. I looked at the job before me and decided that the very next thing I had better do is pause and have a nice cup of tea!
First job was to get a kitchen plastic bag and mark it as ‘old parts.’ Nothing was going to be thrown away. As each part from the scrap carburetor was matched to the new part in the kit, the old part was then placed in the kitchen bag and kept, just in case. Then, I slowly re-assembled the carburetor. I started by rebuilding and adjusting the float chamber section, which also included the accelerator pump mechanism. Memory played a large part in the re-assembly process, but not as much as having to frequently remove the breather air filter section and see what the existing set up was. More than once, I had to undo a part I had just put on in order to get another part installed. Then, I would have to put the other bits on again. The jets were all checked and cleaned out by inserting guitar strings gently down through the jets and removing any residue still stuck in there. I had to be extremely careful with the cardboard gaskets. They are just a bit thicker than heavy paper and can tear quite easily.
The carburetor re-assembly went quite smoothly with a minimum of backtracking and cussing; or at least what I will admit to! Thanks to the schematics and being able to compare the new with the existing old, the job went smoothly.
The trick seemed to be to just tackle one area of the carburetor and then go to the next. Yes, there was some backtracking, but I expected that. For example, I had the accelerator pump all nicely set up and then went to add on the choke linkage. I realized I had to undo part of the pump to install and link the two mechanisms in order for the fast idle feature of the Zenith to work properly. Finally, the ‘new’ unit was rebuilt and seemed ready. There were no bits left over and, if I say so myself, the Zenith looked ready to be installed. Time for another cup of tea!
Before installing the rebuilt carburetor onto the manifold, I decided to find a way to test the unit. The whole thing
looked all right compared to the original and also the digital photographs I had taken, but would it work? I felt the only plausible test I could do was to check the accelerator pump. I poured a small amount of gas into the proper fuel intake tube so that the float chamber would be partially full of gas. Then, being careful where and how I held the unit, operated the accelerator mechanism. It was important to realize that the throttle plate would be open and that the gas would land on my shoes or whatever else was underneath. So this was something to be done outside. I looked down the throat of the Zenith and as I operated the throttle I could see a fine but strong jet of fuel squirt out of the accelerator jet and into the throat. It all worked properly so now it was time to switch the units. I set the mixture and speed control screws to approximately the same depth as the ones already in place. Now it was time for the big switch; it was also a task I had never done before.
I was pleasantly surprised how easy it was to take the old unit off. I had budgeted a whole afternoon for this, but it only took ten minutes to disconnect the old unit and remove it from the Intake manifold. I was flabbergasted when I observed that there was no gasket between the bottom of the old carburetor and the top of the Intake manifold. No wonder the car ran so badly. There was virtually no vacuum for the distributer to operate and the mixture would have been totally compromised. My kit obviously had one, so that was put into position and the Zenith properly installed. Thirty minutes later, I had everything hooked up. Now for the really big test: Would the car start? To my delight, on the third attempt, the engine roared to life. Wow—and to think that I had never done this job before and had no training. My neighbor came over and helped with the adjustments and set up. Crossing my fingers, I rolled the car out for a test drive. My neighbor Jason gave me his telephone number, just in case, and off I went. He advised me to just give it a run around the block and see how the car performed. That was some block. I toured the neighborhood and tested acceleration and holding the car at stop signs and then accelerating away. Previously, the car would have been very difficult and was prone to stalling. Not now! It ran like our daily drivers and I was thrilled! When I got back, Jason came over with as big a grin on his face as I had on mine. A few more minor adjustments to the speed control and the car was ready.
I learned a lot about how carburetors work and gained a new level of respect for the engineers and designers who put this unit together in the first place. I also learned a bit more about self confidence and how with determination and desire, a person can indeed achieve whatever (within reason) they desire. Happy motoring everyone and see you on the road and at the various meets. Wow!
[From The Oily Rag, Issue 121]