jboy381-RCU

would like to get 18K out of it...can you guys help me???

john

jessiej

I expect that as a first step you could open up the venturi a bit.

jess

ballgunner

My Feedback: (1)

There is a high compression head for .049's but it defeats the purposeof the Texaco Endurance engine which is to fly longer on a given amount of fuel. As far as opening the venturi it doesn't have one on a reed valve engine. TD's not allowed so no carburetor to open up. The idea of Texaco is endurance on allowed fuel and the Cox has been designed especially for that with the Texaco engine. Performance is also the reason for the limitation on prop size. You can turn the engine faster with a lower diameter or pitch prop but your performance will suffer.
Airplane design and lighter weight are usually the answer for success in Texaco competition. There are many fine designs that can be lightened considerably as they were originally intended for free flight and strength hence the sturdier construction. One way to help the engine is to make sure the fuel pickup tube is capable of getting the last drop out of the tank. As is comes from Cox the pickup is plastic and not very efficient. Small aluminum tubing bent to the proper angle and attached to the needle valve intake with plastic tube can be a big help. ballgunner SAM #2926

DICKEYBIRD

18000 with what prop and fuel? You can drill the venturi out to .085", put on an open port cyl. with S.P.I. and a Tee Dee head and it should pull a 5x3 black at better than 18000....but it won't be a Texaco anymore! It'll be a Black Widow. Just pick up a good B/W used and run it....save the Texaco for trade or use it for what it was intended for.

jboy381-RCU

dicky do you recognize the tank???it's the one you gave me a wile back...the engine is one i made from a parts lot that i have...i know it looks like a texaco,but it's really not...i'm turning in the pic a 6x3 cox prop on 20% sig fuel...it runs really good the way it is,it dont spit and spudder like the BW(thats another story)i have...i set it up for a film can tank...

if i switch to a 5x3...do you think it'll turn 18K???

combatpigg

My Feedback: (3)

HI JBOY! You can get 18000 with a 5-3, but your thrust will be less than a 6-3 turning at 13000. Expect to get about 9 ozs of thrust. The fuel economy goes way up with the 6-3, and you get a tiny bit more power. If your engine is getting weak, a 5-3 will out perform the 6-3.

BMatthews

If you want pure pulling power at the expense in speed for hard climbing switch to the APC 6x2. I did that on a Free Flight power model that came out overweight and it sharpened up the climb a LOT.

PS: the guys are right. I tried a couple of different 5x3's on the same model. Sounded like a million bucks. Performed like a dead snail even compared to the regular grey Cox 6x3. The APC 6x2 added about 25 to 30% altitude to my climb over the grey 6x3.

If you want speed and don't mine suffering in the climb a bit try a 5x4.

DICKEYBIRD

John, 16K on a 6x3 black ain't bad! Personally, I like the 5x3 black for most of my aircraft. It gives very good thrust and speed, lessens the load (heat) and makes the needle less sensitive....but that's on my planes, at the size & weight I build, with my fuel at the altitude where I fly. I have fixed quite a few Cox's and even a few Norvels at the field simply by screwing on a 5x3. HOWEVER, the tach doesn't have the final word. I would FLY THE AIRPLANE with several different props to see what you and it likes in the air.

My experience with the 1/2A APC's is that they function well on very light aircraft or on Norvels with more rpm available. With their narrow blades, they seem to turn up a lot of revs but (for me) don't hook up. Again, that's been my experience on my aircraft. Like Bruce, I've seen 'em do wonderful things on a 1/2A freeflight model, but that was on a 5 1/2 oz. airframe.

ps: I'd forgotten about that tank, I think its venturi may be already drilled out some. Next time you have it apart, look at the venturi bore; if the ID is bare aluminum, it's been drilled. An undrilled Texaco venturi is anodized red on the inside.

pps: There are 2 types of black 5x3's The early ones don't have the little bump on each blade near the root and have a beveled tip. They're great in a tach race but not much else. The ones you get now are great little props, plus they're almost indestructible.

jboy381-RCU

dickey,
it has already been drilled...i noticed that when i cleaned it for the exturnal fuel tube...i didn't think much of it at the time...

guys,
thanks for all the help...i'm going to get a 5x3 prop and see what happens...i might just leave it alone,because it runs so good...BTW,it has more RPMs that my product engine (15,200)thats on my LS150...both are turning the same 6x3 props on the same fuel 20%...

now if i can get my BW to run this good,i'll be set...a little background,the BW will fire on prime,but once the prime is gone it dies...now i've checked the reed by blowing back and forth though it...it works fine...the needle was next,i cleaned out the hole with a pin drill and it works fine...fuel tank seals against the crankcase and backplate with no leaks...am i missing something???

john

DICKEYBIRD

Make sure the little black washer at the end of the venturi tube is in good shape. Take the needle out and force some fuel backwards through the pickup tube and watch to be sure it squirts out of the backplate. If the reed is working, the washer's good and the fuel will flow to the venturi, it has to run.

fredscz

My Feedback: (47)

Hey Dickybird,
I apologize for butting in but where can I get one of those little black rubber washers. I bought a BW and when it would not run I took it apart and found that washer torn.
Fred B

DICKEYBIRD

I would call Estes/Cox customer service # (800)451-0339 I'm not sure if they offer them separate but I'm pretty sure they sell reed-valve .049 overhaul kits with the washer in them.

In a pinch, you can slice your own from silicone fuel tubing using a new, double edge razor blade. Cut a bunch of 'em and pick the straightest one that most closely matches the original's thickness. They will tear if you make them too thick.

Tim Wiltse-RCU

Call the Cox/Estes number they are .40cent each by themselfs!!!



Later,
Tim

jboy381-RCU

.40 cents[X(] is that high or what...i used the fuel method on the BW...

BTW,i got it to runonly tached 16,800 on a cox 6x3 prop and 20% fuel...

john

Tim Wiltse-RCU

That's not so bad John...almost 17,000 with a 6x3!!! I'd be happy with that myself.

LAter,
Tim

jboy381-RCU

thanks for everything you guys...i'm glad there is a place like this full of people willing to help any one in need now if i just had planes for them

john

Tim Wiltse-RCU

John,

Here is a tasty bit of information for you. On the Care and Operation sheet included with a new Black Widow from 1996 it states with a 6x3 black nylon prop 14,500 and 16,500 with a 5x3!!!!


Later,,
Tim

Japanman

Tim,
I know someone who ordered a new BW and when it arrived (I helped him run it in, so I know) the compression was 'pre worn out' with fuel 2 seconds compression bleed down... []I think it may have made those numbers you mentioned? but being in N.Z and having ordered from the net, there was no point in returning it.
I imagine those numbers are for the engines where the tolerances are near the (sloppy)limit.

J.M

jboy381-RCU

thanks tim,
thats good to know...seems like the performance sheet i D/L from you works like a charm...

john

Tim Wiltse-RCU

J.M,



When I build most all of the engines that I use for myself I fit the cylinder and piston so when they both are dry the piston will almost fall through the top of the cylinder! These are the engines that will really scream...go figure!

Later,
Tim

Japanman

Tim,
Yeah, since then I have found that loose engines seem to run quite well, but for spinning a big prop and more importantly, fuel economy, a tight cylinder ran better.
I wonder if the piston actally expands quite a bit and runs hot- it may be harder to keep the piston cool by conduction to the cylinder being a less heat conductive material than aluminium.
J.M