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bob27s -> Jett .46? (7/14/2003 5:23:29 PM)
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Hi Beau,
Thanks for writing.......
You have a classic on your hands there :)
That is a 1993 vintage Sport Jett engine (image attached). If it is 10 years old, been flown a lot, and is still turning 17.5K fairly well.... it is in good shape.
The 10% fuel you are running is good. We run all of the engines on 10 to 15% nitro fuel. More nitro is not a big help for the engines.
Current versions of the engine will turn a full APC 10x6 upwards of 16,500 - 17,000 rpm. The muffler on yours is tuned for basically the 16K to 18K RPM range, so stick with props that turn in this area and the engine will remain happy.
As for the spinner.......
There is a 1/4-28 prop stud (replaceable) that screws into the crank shaft. The spinner nut should not be 'attached' to it. The stud should be long enough to use a standard spinner/backplate combination, but on some of the original engines they may have been a bit short. Replacement studs are available. You will want to use a GOOD aluminum spinner only. Tru-Turn, Dave Brown spinners are recommended.
The engine should idle quite well. All of the SJ engines and carbs are extreamly smooth (even the original Ram-Jett carb as shown on your engine), and you should expect a reliable idle down around 2500-2700 rpm, with excellent transition. The low speed needle may be way out of adjustment. Take a look at the jettengineering.com web site in the TECH section for instructions on setting the low speed needle.
Let me know if I can be of additional help
Bob Brassell
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