K&B/Veco .19 Venturi Size?

I have a couple of K&B/Veco .19 RC engines I'm planning to try for CL Sport. I'll have Venturis made for them. Any suggestions for starting size? I suppose the operative principle is that it would be easier to drill/machine them out than to replace material ...

Any suggestions on starting prop size are also welcome; left to my own devices, I'd probably start with a 9-6 or cut-down 10-5.

TIA!

When attached to a mid-size model, such as a Streak, I used Tornado 10-4 props. On a smaller plane, I used a 9-4. It was very quick with a 9-5, and downright speedy with an 8-6. I used whatever intake restrictor that Veco supplied, with Veco's NVA, and never noticed any problem.

.

Kiwi

I have a new one with a carb what size should I use if I had a OS NVA {.125}OD thanks Scott Dinger

Dennis,
Check your carb. Some models used the same needle assembly with the carb and the venturi.
I convertrd one and used the stock needle assembly and a nylon electrical spacer from Lowe's. I think I drilled the hole at 1/4" (same as carb). Nylon isn't easy to work with.
A much easier way to go is to ask Leonard to make you a couple. He could probably suggest the proper size.

Hi Dennis,
I have a stock venturi, but am not sure of the size that they are.
These (BB) really run best in a wet 2 and like a 4 pitch prop, unless you're wanting it to fly pretty quick! I really like this engine on the old Sterling KIts. (RM, Yak, Mustang)
Enjoyed meeeting you at Huntersville.
Bill <><

>I have a couple of K&B/Veco .19 RC engines I'm planning to
>try for CL Sport. I'll have Venturis made for them. Any
>suggestions for starting size?

>Dennis

Back in 1965 Peter Chinn measured the throat of the Veco .19B stunt venturi at 15/64 in. (0.234). He did not give the spraybar diameter.

Roman Ramirez

Bill Little writes:

>Hi Dennis,
>I have a stock venturi, but am not sure of the size that
>they are.
>These (BB) really run best in a wet 2 and like a 4 pitch
>prop, unless you're wanting it to fly pretty quick! I
>really like this engine on the old Sterling KIts. (RM, Yak,
>Mustang)
>Enjoyed meeeting you at Huntersville.
>Bill <><

Exactly the kind of thing I had in mind, a Dare Navion kit (basically a remake of the Sterling) looks just right for it. Enjoyed meeting you too, let's get out and fly soon!

Dennis,

I just miked a Series 71 CL K&B 19BB's venturii. As Roman R. said, it is ~0.235 ID. Standard K&B type NVA, with aluminum thimble, not brass. Spraybar OD is larger than 1/8", probably around 0.140".

K&B 19BB manual recommends a "- 9-5 wood for R/C and regular U-control flying. For high performance, use an 8-6 wood prop. Free-flight flying should be done with a 9-4 or 10-4 wood prop." (Note: wood props then available were preferable to 'nylon' ones. Well-balanced wood props vibrated less. We have different materials and better, stiff props today...)

K&B specs claim 0.45 HP at 12,500 RPM. "... no prolonged break-in.." necessary, but avoid fuel with more than 10-12% nitro until after, "...several hours on mild fuel, and under mixture-rich conditions." There's no mention of flying settings, except that after less than an hour, the engine should be safe for "continuous full-throttle and mixture lean operation" when it holds speed and does not sag after a moment or so, after "...mixture has been leaned out..." The degree of leaning out is not addressed: I presume that to mean clearly into 2-cycle, but not to max lean.

Synthetic oils, if used at all back then, were racing or speed-flier experimentation. At that time, oil equalled castor.

Hope this is useful...

As an additional thought, later RC versions of the K&B/VECO .19BB's had a squish band head. This was to provide a bit more power. Not sure if they included this in the stock CL .19BB's.
Perhaps someone has tried it with and without the squish band and can share some information on the running characteristics of both.

I have a K&B Veco 19 on an ARF Flite Streak that I'm going to try with an APC 9-4, like the FP 20s run so well. Weather has prevented a test flight yet, but it turns up nicely, so I think it will be fine. I'll let you know in a few days how it goes. BTW, stock venturi, NVA and muffler, exhaust hole drilled out to 3/8th.

Hi George,
I will try that experiment with mine when it takes to the air again. I have two "new" 19BBs. One with the early head and one with the later style. The later one has taller fins on it, and looks more like the K&B 40 head. The early one looks more like the Veco 35 head.
Will be a while before I can compare, the plane needs to be finished!
Bill <><