Dennis, I'll move over to this forum for the Sledge discussion. I have 2 of the ST.51s, and I used one on a TopCap with good results. I ran mine with a Macs header and mousse can pipe. With this set up I found the OS 8 glow plug to work the best, and some others that I tried would barely run at all. 5-10% nitro on the fuel is good enough. A 11x4 Zinger prop is just about right. Set your top end needle close to right, and then adjust the low needle so when you quickly open the throttle after a 15-20 second idle there is no hesitation. Now re-adjust the high needle 2-4 clicks rich of peak. I've always had good luck with the Super Tiger engines. Tom