Daytona Carbs

Although I’ve been pretty busy at my shop near my home, I still try to find time to go to Connecticut to work at Francois’ shop. He’s been just as busy as I have been, but he’s taking less work to try and relax his work load. My going down to his shop was to try to help get some long term projects out of his shop and relieve some of his stress. One such project was a Daytona engine rebuild in the car behind me.

Now that the the engine is rebuilt, there were still a bunch of little details to take care of, and one of them was to replace a carburetor top that had gone beyond its regular service life. These Weber DCN carbs have a week point where the fuel line attaches to the carburetor. To cut costs, Weber cut the threads directly into the zymac casting instead of using a brass threaded insert like they did with previous carburetors. Through time, the threads weaken and eventually pull out, and previous attempts show someone tried a helicoil insert, a brass collar, and even epoxy to stop the fuel leaks. GTO Engineering now offers a new replacement carburetor top, and we would see how well it worked.

All the holes lined up, and the dimensions were relatively close, but there was still some tweaking we needed to do. The tabs holding the float were slightly thicker, so when I installed the old float, it would bind in between the tabs. A bit of filing, and I got the float to move freely.

We found the carburetor was missing a crucial plug at the fuel fitting end that wasn’t installed. The main feed line was drilled, but never capped so when the fuel line was pressurized, fuel cam pouring out of the open hole. We had to remove the top from the carburetor and plug the hole.

We made a tapered aluminum plug and installed the missing plug. The original plug were made out of lead, but I wasn’t sure if it would work the same way in the aluminum since the original piece was zymac. The second arrow showed another issue we had with this replacement part and that was the thickness of the fitting. GTO made the fuel fitting slightly thicker than the original dimension pushing the banjo fitting further out by about 1mm, but when replacing only one carburetor top, this fitting wouldn’t align with the other carburetors because Ferrari uses a rigid line between the carbs. We’ll try shimming the other two carbs fittings, but it’s good to note, these carbs are not simple “plug and play” items!