OK so with the bad weather and such I have spent alot of time in the shop. I got the new Sniper DR .049 prototype done and running today. So far so good! The second backplate is on the machines right now. The set up is a stock Cox reed valve front end(case,crank) with my machined backplate disk rotor setup. So far running an old whipped TD cylinder, regular Cox head with 2 head gaskets, 20% nitro fuel with the venturi around .100 or so, it's running 19,100 on a APC 5x3, Cox black 6x3 pulled just shy of 16,000. So with some tweaking we will see what it can do. The intake needs to get opened up and the timing needs to be opened up too! But I will be very happy with 17,000rpm on the Cox black 6x3 and I think that will be pretty easy. My home computer is dead so I can't post any pictures for a couple weeks when we get a new one. Of course the weak link on the Cox parts is the ball socket so I won't push to hard

Later,
Tim

Hey Tim, we missed ya at the meet, I have your hat and 2 engines and rebuild kits that I will mail down to you ,when I can get to the PO...If you like these rebuild kits let me know as I plan on ordering some more,he only had 2 but is waiting on more, at the meet I got 2 of the product engines with choke tubes on them both brand new engines for $10......Rog

So I had a batch of anodizing to run so I threw some of my parts in while I was at it. This is the finished Sniper DR(disk rotor) .049. This is my second proto using my new milling machine. This engine was happy making 18,200 rpm on a black Cox 5x3 on 20%nitro. It will turn a Cox black 6x3 at 15,000. It is a very easy engine to start and I was hand flipping it 90% of the time. This was in 30 degree temps while it was snowing/sleeting here yesterday.

Later,
Tim

Very nice! It looks like it's hooked up to a LAKEWOOD SCATTERSHIELD!

Tim,

That engine looks GREAT !!!... Let me know when you get something ready for testing....!!!


Dan

tim awsome engine dude!!!as all ways you are the man for custom cox engines...

did you make the backplate on your milling machine???if you did i need a huge favor...i've been trying to make somesort of mount for the product engine with the choke tube...everything i try comes out looking like sh#t...i'm thinking maybe you could hook me up with a custom mount???

what do you say???
john

Dude I have already been thinking about you!!!! I just have to get some stock to cut.

Later,
Tim

SWEET

john

Hey, what jboy said...I got 2 of them let me know about the mounts too...Rog

Well, I just used a couple pieces of 1/4x1/4 for spacers on the firewall. Top to bottom of course, and the choke tube slid right between the two pieces.
Nice work Tim. Will these ever make it to your line-up or is there too much work involved?

Patrick,

Yup thats the plan I am starting on "production" today as a matter of fact.

Later,
Tim

Very cool! You are an inspiration!

OK... so I have been messing with this engine alot over the last week. Final tach numbers as of Friday night was 20,100rpm on a APC 5x3 running a brand new #1 cylinder/piston( twin bypass NOT TD), regular glow head with 1 head gasket on SIG Champion 10% nitro all castor, either 20 or 25% lube. After reading over my old "Norvel Killer" thread I remebered AJC's chart about intake timing, Japman thought that the little engines would be happier with the intake closing sooner than 30/35degrees ATDC due to the short intake track they have. I made a rotor( it sure is nice to just be able to make a different rotor than a new crank) with the intake closing 20degrees ATDC. The engine HATED it and barely ran at all..go figure! I will go the other way when I can make a different rotor this week with 40 degrees in it.
So I mounted the engine up yesterday afternoon to my Sniper(last years contest plane). I have a balloon tank in this plane still from when I was running my reedies on it. The engine would start very well and run solid till I tosed it at launch then it would just flat out die. Two or three times of that and I knew something was up with the fuel draw. I changed to a smaller venturi and that helped. I got in a couple three flights. I was launching it a few clicks rich thinking it will lean out as the prop unloads in the air. Well every time it would richen after launch. It still had a ton of power and ran solid though alittle rich. Late last night I took the plane apart and realized the pickup on the balloon tank was maybe almost 1/2" higher than the needle ..DUH! So that was most likely a big part of the problem. This would also be the reason I flooded the engine a few times..DUH again. So I'll re-rig the balloon tank and run her some more.

Later,
Tim

Hi Tim,

I wanted to know how what you did with regard to the length of the crankpin? Earlier you said that you had shaved the connecting rod so you could hook up to the drum, but then I thought you said you were going to try to extend the crank pin, so what did you finally wind up doing?

Bill S. (the other Bill)

Bill,

Well so far I have just narrowed the bottom of the rod. So far so good. Friday night I ran it for a good 25 minutes straight, filling the tank before it was empty. I was figuring that if something was going to break that was the time

Later,
Tim

do you have a waiting list yet tim???if not ,put me down for one...20k on a 5x3 is awsome...no wonder the rich needle made much difference...i bet the C/L speed gang would love your engine...

john

Sounds like you got a Cox running almost as good as a Norvel does out of the box!

What a smartypants

Later,
Tim

Hi Tim,
I am very curious about what you find out- I'll be making a cox 049 disc rotor intake engine for my contest plane when I get back to Japan in 3 weeks or so. I am surprised that 20degrees didn't work. I was planning to start my experiments with intake closing at 0degrees ATDC and then 5 deg or so. As I said before I would have thought that less closing lag would be better but there could be a number of reasons why a particular engine may not like it, some of them vexious
I have been thinking broadly that it would be good to make the discvalves in some convenient way i.e a holesaw so I could smack out 10 blanks to try a few different timing configurations.
Stefan

Hi Japanman,

How about turning a rod down to the proper diameter, and then cutting discs off the rod with a saw?

Bill S. (the other Bill)