Jett 46
 

I just picked up a jett 46 with a quickee 500 carb and nelson racing head. My question is I called jett and they told me they never set a 46 up that way. I would really like low speed adjustment, Jett told me I shouldnt waste my money on a old motor like that. Any way it has 46 etched in the side and it is pulling a apc 10x6 at 17400. Does this sound right?

RE: Jett 46
 

I had a stock SJ 46 years ago and your numbers sound (almost too) good. I would fly it the way it is but you could add a different carb for a good idle.

RE: Jett 46
 

Do you know what carb to put on it. It will idle for say 10-15 seconds then when you hit the throttle it blubbers for 2-3 seconds then all hell breaks loose. I cannot believe this motor, it blows my mind. I swear the thrust is like some of my big gassers.

RE: Jett 46
 

You could buy a Jett carb - their comment notwithstanding - or Perry carbs work nicely. Pricing is on Jett's website I think. Jett carbs have a few details in their design that would probably give you the best transition, but I can't compare from personal experience, mine have Jett carbs. If it is a .46 then it is a "sport" timed motor and should behave well with a carb. If the engine spins a 10-6 at 17,400, it's definitely up to par IMHO, and it sounds like it is worth a try with a normal carb. I think Jett's advice is sound, in that they are saying don't pour money into it - but carbs are in the two-digits and if you end up with a nice running $250 engine, well then.. ? It ends up being your decision in the end. Got an OS .40/.46 carb around you could try on it before you spend money? You'd get a better idea about transition and mid-range.

Odd that someone would massage a .46, but perhaps they had the bits around and just wanted a really fast sport plane.

Yes, they are that strong by the way. Great engines.

MJD

RE: Jett 46
 

this aint yer daddy's OS...lol

RE: Jett 46
 

Thanks for all the info, I have a os 46 ax carb I could try. I think I will fly it like this just to see what happens.

RE: Jett 46
 

It would be interesting to see what your rpm figures are after changing to a smaller carb. The idea is to see if the OS carb is being restrictive at 17400 or not.

RE: Jett 46
 

You aint kiddin.

RE: Jett 46
 

I will try it and let you guys know. The venturi on jett carb is huge compared to the os.

RE: Jett 46
 

Nothing much in physics comes for free. You'll probably lose a bit of top end and gain a throttleable engine. 17.4k is pretty darn honking for a .46 on a 10-6, so don't be disappointed if it drops a tad with the OS test carb.

MJD

RE: Jett 46
 

If it runs that good, don't muck with it. Stick it on a speed plane and go like heck. Sound like the carb is good for full speed and shutdown....Perfect!

RE: Jett 46
 

Well, it's about how much HP can that size hole support? Guys were running Grand National NASCAR with 500 cfm carbs in the good ol' days while your typical street punk hotrodder had a 780 on his 327 Chevy spitting raw fuel out the pipes. I'll bet JETT did plenty of testing to see how big of a carb they could get away with...or perhaps it should be looked at more like they did plenty of testing to see how small of a carb they could get away with and still maintain a high level of performance?

RE: Jett 46
 

Well I tried to put the 46ax carb on it. Way to small I even have a os 7d carb still to small, the only carb that would fit was a super tigre 2300. The od on that jett carb is huge. Did some more testing, with a 9x7 apc I was getting 18400 rpm. I guess I will have to order a carb from jett.

RE: Jett 46
 

Any plane recommendations?

RE: Jett 46
 

I'd leave the engine alone and put it on a Screamin' Demon if you want speed. Run it with a 9x8 prop and run it as rich as it will tolerate until you get used to the speed. Not so rich that there isn't good thrust for launching, but set it so it's belching smoke and just begining to 2 cycle. Think of the carb as an emergency engine kill.

RE: Jett 46
 

I understood the single needle carb from Jett would let you throttle back but the idle was not good. If you consider 8,000 - 10,000 rpm an idle you are good to go. I am with cp, put it on a Screamin Demon and have fun. Jett has three tuned mufflers. Do you know which one you have?

RE: Jett 46
 

Heres a couple pics

RE: Jett 46
 

looks like we got a race brewing for sunday;)

RE: Jett 46
 

LOL ya if my wing doesnt blow off.

RE: Jett 46
 

That is the SS tuned muffler tuned for 17,000 - 19,500 rpm. They have a longer one and a shorter one.

RE: Jett 46
 

Thankyou, for the info. I hope it doesnt blow the wing off of the lucky stik.

RE: Jett 46
 

I do not want a delta wing. I would like to go more traditional airplane.

RE: Jett 46
 

That stick would be real fast with a thinner wing....it's probably pretty fast now but you would see a difference if the wing was thinner.

RE: Jett 46
 

It is a .40 - CAPS racing setup, SS carb, with the nelson/jett glow plug head. Has the SS sport racing muffler.

None of the .46 engines were built that way.

Engine will run great. But be aware, although it is designed to idle and throttle (to meet the sport racing rules), and it does do that, that SS carb has no low speed mixture adjustment. So to be more direct, it really is not designed as a fully-featured throttle. We used it either wide open or shut down.

Obviously you already saw this. With a smaller prop, you have a better chance of at least lower power and midrange. But do not expect much lower than a 3000 rpm idle. Plus, the nelson plugs tend to go cold on you quickly at low power settings, and then will not transition out from there.

(although, sometimes racing these things, they would idle too darn good and would not shut down for landing...... of course, with my favorite prop on the shaft)

You want to prop the engine to run no less than 17,000 rpm, and preferably over 17,500 peak ground rpm. 10x6 is as big as you want to go. The APC 9x7 would be better. On a Q-500 type design, an APC 8.5x7.25 is a great choice too :)

My suggestion ........ use the engine for what it is ........ by the time you replace the carb (and maybe the head button) it is a bit of expense.

RE: Jett 46
 

Thanks for the info bob, The only reason I thought it was a 46 is because someone etched 46 in the side of the motor. I will be staying with the 9x7 apc it seems to really like it.
Once again thanks for the info.