controlliner

Make the intake ID 3 mm.

gkamysz

My Feedback: (19)

3mm might inhibit high RPM performance. The stock carb is 4mm.

forsakenrider

Thats about what I was thinkin, keep it stock. Im hoping it will run on suction! I wonder if theres any where else on this little guy one coudl lighten it up. It sure makes a norvel .061 look like a midget!

controlliner

If you compare an R/C carb to a venturi, the carb will always be larger. Compare it to an AME 049, 4 mm will mabe cause reliability problems . Try opening up a TD .049 to 4 mm and see the problems that result.
It all depends whether the venturi will have a spray bar through it or if it uses the Super Tigre "sprinkler" type intake configuration.

gkamysz

My Feedback: (19)

It's pretty safe to say this engine flows more air than a TD. It should be obvious that actual cross section area(including spray bar, etc.) is more important than the diameter itself. I was going to make several venturis when I get around to it.

forsakenrider

Well maybe I should start with 3mm, its easy to drill it out after. My norvel is drilled out to 3/16" which is just over 4.75mm and it runs excellent, but it needs pressure. I will be using a spray bar like a Norvel C/L engine.

Any other ideas on the shape/size for a venturi? It looks like I will make it into my buddies shop tomorrow evening. Maybe I will try and make a couple.

g-rock

My Feedback: (1)

AndyW,

THanks for your help!

I have finally finished mine but I have not run it yet.

The prop shaft adaptor is made from a short AN 4 (aircraft) bolt and is patterned after a Maxx Products type electric motor shaft adaptor. It is also internally threaded so that it can be jammed up against the bearing before the internally tapered prop washer closes the collect end.

Decided to machine a new head so that it would look like the big boys.

The muffler is patterned after a Norvel .074 muffler. I used a silicone O-ring just to be safe.

I initially made a Norvel type carb body and used Norvel guts but my order to New Creations R/C for Norvel carbs did not pan out. The site states that they removed all of the parts from their site that were out of stock in 2008 but obviously haven't updated their site since.

The carb in the photos is from the AP .061 Wasp engine from Hobby People, and, the price is right at $15 for the complete carb. Made a light press fit sleeve to adapt the AP carb to the Picco then machined a 15° taper on the bottom inside so as to match the opening in the Picco crank case. I added an air-bleed using an 0-80 socket head cap screw but put it on the wrong side, so I added a second and plugged the first. I guess the first one would have worked - must be the old age setting in.

Gene

fritzke

My Feedback: (1)

Ah, childs play for a guy who can scratch build helicopters!
Looks very nice G-Rock. How much is the Picco Z anyway?
Dave

g-rock

My Feedback: (1)

Dave,
Tower Hobbies had them for about $150 but it is now discontinued. Nitrohouse still has them for $50. See post #69.
Gene

AndyW

My Feedback: (1)

Gene,

You're certainly welcome, glad to help. That's a very nice head you've made up. I had to cheat and use an MP Jets head for the hybrid. I'm just curious,,, I have a Taig lathe, how does one go about making heads from scratch?

g-rock

My Feedback: (1)

AndyW,
I have several lathes and a square column milling machine etc. and I also have milling attachments for all of the lathes. The head was made using the milling attachment for my smallest lathe, a 6" Atlas. I started out with square stock so that I could cut the fins with a 1/16" width 3" diameter saw blade. I use a micrometer lathe bed clamp to control the fin spacing. The micrometer bed clamp is one of my most useful attachment for my lathes. The bolt pattern and plug hole are also done in the milling attachment. Most of the rest is done with the 6" lathe.
Gene

Toad

I'm thinking maybe I can make this piston/sleeve combo work for pylon
A guy can get the whole engine for 4 dollars more than the sleeve set for the GZ's and I bet the quality control has to be better than the GZ

AndyW

My Feedback: (1)

Thanks Gene,

I never thought to try with a square blank. Makes sense and much easier.

Toad,

I don't know the quality of the GZ these days, (I have an early one) but yes, the Picco's innards, like the rest of the engine are impeccable, with a streamlined conrod, very light piston and circlips holding the hollow wrist pin which has a larger than usual diameter. My only disappointment was that the piston end of the rod wasn't bushed. But Picco knows their stuff, that large pin makes up for that I'd bet.

I have a second one which will be hybradized with a Norvel. This one though, will be strictly diesel.

RocketRob

My Feedback: (1)

Grock - simply gorgeous!
Is there an option to increase the size of the AP carb inlet and barrel?

How is your muffler held?
Thanks Rob

g-rock

My Feedback: (1)

Rob,

The AP carb inlet is about 4 mm and the hole thru the barrel is about 3 mm. The carb barrel is about .233" in diameter - not 6 mm (.236") like the Norvel carb barrel and I do not know if it is hardened but I suppose that it could be opened to 4 mm with a carbide bit if necessary. The openings and the design of the AP carb is very simular to the .074 Norvel.

Look at the left-hand side view for the muffler mount (photo 3). it is held on by 2 #4-40 socket head cap screws.

Gene

RocketRob

My Feedback: (1)

I see said the blind man. It looks so like a norvel muffler I was looking for the funky little wire retainers?

I need to measure my OS .10 carb I am using, as originally I eyeballed it to the supplied car slide carb and it was on the shelf, so well you know what happened next.

I have since picked up one of the AP carbs and it looks tiny by comparison. The OS .10 seems to transition pretty well with a 4.2x4 though

Toad

Here is my version of this engine. I am really impressed with the quality of the parts.

build light

It is a beauty!

Robert

Toad

On my venturi, I went with a .180 throat, the carb that came with it also had this bore, ( I used gage pins to verify this. ) I am kinda shocked because the passage through the crank is .186 dia, I thought I should go down to .165, where I used to run my Cox TD's, Well, I ran this with the .180 venturi I made. I was pleasantly surprised, no needle setting issues at all and it started right up.
I think a 3mm throat would be way too restrictive for this engine (.118)

forsakenrider

im still trying to get a damn venturi made! any chance you might make another Mr Toad? and one for a norvel we've talked about for a year :P

gkamysz

My Feedback: (19)

Cool. So the 4mm venturi works fine. It's cool to see more of these coming together. Mine is on the back burner for now. Too many other paying projects to work on.

Toad

I can make venturi's.. the issue is the spray bar stuff intended for use.
I just dont have any extra needle asemblies, I am sharing this one with a GZ.
Forsaken, I can make you a venturi or two, I need to know what spray bar diameter you plan on useing.
I used the VA spraybar's on my norvels, 4mm dia. The GZ and this picco use one that is 3.5mm dia
On the picco, I had to enlarge the hold down bolt hole to accept this spray bar... It is not as easy to do as it looks.
I will be on vacation now Untill Aug 3rd.. I can make you those two venturi's as soon as you let me know what spray bar you have for them, when I get back home.

forsakenrider

alllllright awesome, I sent you an e-mail!

thanks in advance.

Toad

Here is what I have decided to go with for my Picco's
I will fly one this weekend and let ya know how it goes.
I am planning on seeing how it turns the 4.2x4 apc (the pig's favorite prop)

gkamysz

My Feedback: (19)

Looks good. I should finish mine. I made a head, but didn't finish the drive parts.