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MAC .21 Engine CMDI is proud to bring to you the Mac 21 Buggy engine. The Mac 21 is already taking the the Buggy tracks by storm. The Mac makes use of the same knowledge and expertise used in our record setting Marine engines. Low end power is no problem for the Mac 21. Power way through traffic exiting every corner and leap whoop-ti-dos with a single punch of the trigger. With the Mac engine you won’t be left in the dust. After a few laps around the track in won’t be long before you are king of the hill. MAC Mods In order to get that low end punch that you're looking for, you need to aim for late clutch engagement. The Team MAC drivers are all using the following (but other combos DO work): Mugen aluminum 3-shoe clutch, lightened by drilling a 3/32 hole in the end of each shoe. 1.0 springs (the 1.1 seem to break a good bit) 13T clutch bell. We've tested the OFNA 12T clutch bell (5x10 bearings) and found that yes, it gives the MAC tons of bottom end while maintaining excellent top end BUT Andy would rather rely on clutch adjustment (6 of one, half dozen of the other) for bottom end for the Team drivers because the bearings with the OFNA 12T don't seem to last very long, even when we replaced the original clutch bearing with a higher quality one. They were just wearing out too quickly for Andy's liking. I understand that Kyosho makes a 12T that is meant to be a little higher quality, and we'd like to try it but they're hard to get at the moment. We will be testing a 4-shoe clutch soon. I will let everyone know about the results of that testing as soon as I know. Overall, drivers (even the lesser experienced ones) are winning with the MAC whether it's been modified or out-of-the-box bone stock. MACs are taking TQ's and A-mains just about everywhere they're running. It's quite impressive, even from my standpoint (company employee and all...). Every driver that's dropped a MAC in his/her car has had greater race results because the power is so smooth and the MAC is so easy to drive. On to the carb - I don't recall if I sent this to you or not, but Andy has given me step-by-step instructions on how to tune the carb for the very best performance. 1) remove the high-end needle assembly 2) set mid-range needle flush with carb body 3) looking AT the midrange needle THROUGH the hole in the carb body where you've removed the high- end needle assembly, adjust the mid-range needle (plus or minus) until the hole in the side of the mid-range needle is lined up directly with the high- end needle assembly hole. don't touch this needle again. 4) reassemble high-end needle and thread it back in. 5) for initial run, set high end needle 2 1/2 turns out (open) - this will be a rich setting. a good needle should come to about 2 1/4 turns (after first run, lean out usually 1/4 - 3/8 turns in) 6) low-end needle should be flush with side ball arm. 7) set slide stop screw 1mm open (about 1/8 turn out) Skinny at R/C Car mag will be publishing a full review of the MAC in the next issue. Be sure to look for it! |
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