I understand that it really needs 0% nitro but will run ok with 5%. I have a Fox .50 and it runs hot with 10% in the summer, runs fine on 5% all year round. Same with an old ASP redhead.
Actually, an ASP .91 Redhead is exactly what I replaced the .74 with! I fussed with that Fox for an entire season. Being very familiar with most Fox engines, I was sorely disappointed with the .74. When I initially started it, the engine would go rich and die. That is when I found the defective needle valve and body. One call to Fox, and they sent one to me. Great! Now I could get it to run and stay running. But, I couldn't get any power out of it.[&o]
I tried 0% nitro fuel (I was running it in an ST2000), that didn't help. I tried adding castor to the already castor blended 10% fuel, that didn't help. I tried different props, that didn't help. I tried adding shims under the head. That didn't do it. I tried every conceivable needle setting. My Fox .74 would not run worth a crap. I literally "fixed it" with a 5 Lb. sledge hammer.[:@]
The ASP Red Head .91 ran hot on it's first flight. One extra head shim, and it was running like a champ. That engine probably has over a thousand flights on it now, and still runs very well. I really should replace the bearings in it. But, I'll just run it till it pukes and pitch it. It has had a great life.
