Carburetors

It was a rainy cold day in Seattle and after watching another lackluster Ferrari showing in the Turkish F1 race, I decided to do something on the coupe that could be done in the house.  So I pulled out the carburetors and various associated parts to figure out what needed to be done.

When I bought the car, the carbs were nicely done in a black powder coat, so I assumed that they had been rebuilt.  Perhaps powder coated a little too nicely since they also painted the top where the air cleaner fits on.  As I was looking, I realized that they had been taken apart, powder coated and then just partly reassembled.  Here are the various parts as I took them out of several plastic bags.

The carbs on the 128F coupe engines are Weber 40 DCL 6 models.  These are essentially the same carbs that came on the majority of the 330 GTs except the body of the carburetor is aluminum (DCL) instead of zinc (DCZ), so I had the 40 DCZ exploded parts diagram from the 330 GT parts manual to work with.

As you can see in the picture, the parts on the left were in one bag and look like they were all sent out and gold cadmium plated.  The ones on the right were in another bag.  I thought that they were used extras as they had nothing done with them after disassembly.  I took the top off one of the carburetors to check the float, etc. and found that the gasket was reused.  So much for having been rebuilt.  As I was inventorying what was assembled and what needed to be done, the major items like the throttle shafts, plates, springs, levers, etc. weren't installed.  After counting the parts, I could see why: the gears (39) for the second throttle shafts were missing.  Evidently they got to that point, realized that they couldn't finish and buttoned everything back up.

In addition to the gears, one choke lever (46) and one of the linkages connecting the carburetors to the accelerator shaft weren't there.  The linkages were also missing all of the lock nuts and spring clips that hold the end balls into the sockets.  The clamps (51) for the end of the second throttle shaft were gone along with the bushings (47) for the choke adjustment screws.  As I was thinking about the missing linkage, I realized that I couldn't remember seeing the accelerator shaft and linkages that mount to the valve covers.

As far as the carbs go, I sent an email to Pierce Manifolds detailing what I was missing to see if they could rebuild them and supply the missing parts.

On parts 31/36, there were five loose springs, three of one type, one slightly different and one quite different. So it is possible that I have one correct set but which I don't know as one can't tell them apart from the parts diagram.

So now I wait.  In the meantime, I just bagged up everything and set it aside.

I had a long talk with Mike Pierce with Pierce Manifolds.  He only has 2 of the throttle shaft gears and was surprised that he had those as they have been NLA for years.  It turns out that they were on back order with Weber from 1999 and those two showed up about a year ago.  I suggested that he check if Weber has anymore and he said that 40 more were still on back order.  I bundled up the carbs and loose parts and sent them off to Mike for evaluation and to see what other parts might be needed.  I also sent an email to Shaughnessy to see if he has a junk DCL or DCZ carb that could be used for parts.  Lastly, I asked my friend Buddy who is a bronze sculptor if he knows of anybody who could cast a small run of this part.  So one way or the other, I should be able to source the part to get all three carbs rebuilt.

Mike Pierce received the carbs, looked them over and called to give me the bad news.  The previous owner had had them powder coated, but they weren't done properly.  First, Mike thinks that they didn't prepare them properly to get the 40 years of fuel and oil residues out of the pores (these are sand cast bodies).  So the first try probably failed with fish eyes, etc.  So they put a second powder coat on.  The worse part was that they used a high temperature powder and that melted the lead plugs that Weber used to seal off the passages for the various circuits.  The powder coating will have to be stripped and then these passages will each have to be tested and reamed of any lead remaining.  After that, each circuit tested to make sure that it is working correctly.  Further, some of the parts were improperly plated and are now too thick, so they will have to be stripped.  Others have the wrong plating and will need to be redone, along with have correct powder coating done.  This will be done on a time and materials basis, but Mike said that he could see $2000/carb plus the plating and powder coating.  Of course, the throttle shafts are worn and need to be replaced with oversized ones and the carb bodies reamed to fit, but that's just a drop in the bucket.

I got an email from a Weber parts place in the UK and they have a throttle shaft gear.  I also asked them about the other minor parts before ordering.

The UK place didn't have any other Weber parts, so I'll have to make a few.

The missing gears from the UK came today.  Not much to look at, but when they are the last few in the world, I'm quite glad to get them.

Got an email from Mike Pierce today. The carbs are done and the bill is only $3784.02, so with the parts I bought plus shipping, etc., just a little less that 4K. About 1/2 of what it could have been.  Also had another long talk with Mike Pierce. He has a Weber catalog from 1964. These carbs are listed with a retail price of $39 each!

Mike even puts on new Weber plates with the original type and serial numbers stamped in.  I was thinking that I would have to get some blank plates from Parker Hall and do them myself.

Among the other missing parts were the little bushings (#49) that fit into the end of the choke lever that allow the choke cable to rotate slightly as the choke is pulled.  I measured up one on my 330 GT and came up with these dimensions.

   

I found that McMaster-Carr had some steel stock that is 8mm OD and 3mm ID, so I ordered a piece (1 meter long).  The first step was to drill the 3mm center hole to 4mm.  Then I chucked a short piece in a drill and used a grinding wheel to cut the outside down to 7mm.  After that, using a cut-off wheel, I narrowed a couple of short sections down to the 6mm size.  Finally, I cut the three pieces off, each 4mm long.  There are times I would really like a mini-lathe as parts like these would be easy to make on one.  The last thing I needed to do was to drill holes at the top of the cheese head screws for the choke wire to fit through.

       

I also have to make one choke lever (#48) and its clevis pin (#58).

The clevis pin was pretty easy.  I started with a 5mm bolt, rounded off the head, ground away the threads down to the proper diameter.  Then I shaved the head down until it was the right thickness.  Finally, I drilled the hole for the cotter pin.

The choke lever was a little more complicated.  I found some scrap that was a little too thick but as close as I had.  Then I drilled the two holes, one in each end.  By putting the drill bits in the holes of the original and my steel stock, I was able to use a scribe and trace the outside pattern.

   

I closely cut each end and rounded them on the grinder.  For the straight sides, I used a cut-off wheel to cut slots close to the line.  Then using a saber saw with a metal cutting blade, I lengthened the slots as far as possible.  Finally I finished up with a hack saw.  Careful grinding trued up each side.  Once the shape was done, I had to thin the material to match the original.  After some thought, I used the stationary belt sander, using a couple of magnets on sticks, and let the material rest against the fence.  It took quite a while, with lots of cooling needed.  But finally it was down to the 2mm thickness of the original.  Here are the original and my parts, along with the newly made ones installed on the carb, including the choke clamp screw.

   

BTW, the levers are the same length, the wide angle of the picture makes them look not so.

After some thought, I decided to re-plate several of the carb pieces that were gold cad plated.  If you look on the picture above, the screws holding the top on and the accelerator arm and nut are gold colored.  I used Caswell's copy cad kit to re-plate these parts.  As you can see, the various parts look much better in a silver cad color.