not sure, but can tell you, those are not the ones to worry about.  Its the 2 holding the carb in place that you will lose.  I took to using some jb weld to hold mine in place and tossed the screws away

         Andrew, I replaced the screws on my Stels engine due to the slotted screw heads would blow off. Those screws were 2mmx4. Dubro actually makes those screws available in the r/c car section of most hobby stores and they come 6 to a package. I paid $1.99 for them. The stock # was 2111. They come in a Dubro racing package which is black white and orange unlike the red and yellow packages Dubro supplies. These screws have worked in my Norvel's as well as early AME engines. I see no reason why they would be any different for the AP. Ken

Andrew,

I used a longer screw all the way through the venturi, with a nut and washer on the other end. Much easier to make a venturi without threaded holes.

All the later Norvel .049/.061 engines used the same through screw arrangement, and there doesn't appear to be any performance penalty with any of these engines.

Better yet, order a venturi and spray bar from Jan Holuszko here on the forum, and use the stock needle, o-ring, and ratchet spring from the AP carb.

Bill