.21 valvola engine question.

[Marty Davis]

Marty,
What do you do when the low end needle makes it physically impossible for the engine to flow enough fuel at top end?

Preston:

I don't have that problem with the carbs that I am running. On the .21 I run the Black Picco Carb and it works awesome. Since I don't run any of the larger boats any more, I don't have that problem. On my 1/8 Scale (before I sold it) I ran an older Rossi Carb which would allow me to PUTT PUTT PUTT as slow as I wanted and instantly accelerate. That is my driving style (to be able to go as slow as needed), but I realize that is not what MOST people like. That was the reason for the qualifier on my original post.

I agree with you that some carbs have that problem. ESPECIALLY the OS carbs. As I indicated to Chris, the ones that I really like best have the rectangular opening in the tube that the needle plunges into.

Marty Davis

 

[Marty Davis]

Hey marty,
I havn't used a low speed.. But i guess i felt like i really never needed one.. Last few years I have noticed that it mills really well and i can slow down ALOT without it, that is why i havn't used one.

I will say, i am using the nova rossi carb.. with all the low speed stuff cut out.. Now with that being said..

I noticed about 2 yrs ago. I used to use a barrel for the nova carb that dad made that rotated in the barrell.. I switched it to the barrel that nova sends that rotates and also screw's in and out.. THAT helped the throttle ablility a TON.

chris

Chris:

All of the carbs that I like have that in and out motion where the needle plunges into another tube. The key seems to be the opening in the tube. The ones that I like have a rectangular opening in the tube.

Sometime, give one a try, and see if doesn't improve your overall performance (including launch).

Marty Davis

 

[tmunn]

you guys stop hijacking my thread and help me.... :lol:

I was out again for a couple hours till my steering servo got wet..

Here is wat I tried

The pipe was lengthened to 8.75" same prop.X440/2 still went better at half than full.

Tried same lenght pipe and m440/2 still went better at half than WOT

Tried the same length Pipe and X438/2 still went better at half than WOT.

I left the 438/2 on there and started going in on the HSN and it seemed go better on the top end and when you let off the throttle the increase in speed and engine singing out was not so noticable.

I am just nervous to get it too lean. and fooling with the fuel mixture when i am compensating for something else..

I was making progress then i had my steering servo get wet.

I will try again once i get the servo dried out and my radio mox more waterproof.

Thanks a lot guys but am not a lot further ahead.The engine seeks to pull the props i have tried and the pipe is out as far as any i have seen on the forum running this same setup ??

Terry

 

[norm j]

:unsure: terry you may have a leak in you fuel delivery system or not enough pressure going into the fuel cell,it sounds like the motor is starving for fuel,double check your fuel lines and fuel cell

from norm

fmbc

 

[tmunn]

I will check the fuel system out again i had a similar problem during my first configuration when I tried to run double tanks , when it switched to 2 nd one it would act like i lost pressure.

I figured it was starving for fuel as well.that is why i went out on the HSN and it did notseem to help.I will check it out again.

I am using a small diameter pressure line which is 3/32" fuel tubing.This should give me good pressure if not leaking <_<

That is why i decided to go with one single tank in the front and move my radio box to the rear.

I will try it again in a few days and see what happens.

I will keep you guys posted.

thanks terry

 

[Brad Christy]

Terry,

If you don't want to cut off the needle then try adjusting it. The way they are supposed to work is that they start to lean the mixture as you close off the throttle so that the engine doesn't load up at low speeds. To get it set up to where the mixture stays consistant may take some adjustment. Once you find the sweet spot, it should not require much attention in the future.

What you've got going on is that the LSN is leaning the mixture too soon as you close of the throttle. If you "richen" the LSN, this will delay this instance so that the throttle is closed further before the mixture leans out. What I'd suggest (if you don't want to cut the thing off and be done with it) is to open it way up so that it doesn't really do much at all. The start leaning the LSN, a little at a time per run, until you get the behavior you're looking for.

Psersonally, I think it's just one more thing to worry about when something isn't right and you can't put your finger on what it might be..........

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

 

[ids987]

The LSN on the CMB carbs is really more of a mid-range needle than an idle needle. If you try and adjust it to get a really slow and smooth idle (like you can with OS and other "proper" carbs), the engine will go lean in the midrange, and most likely you may not be able to get it rich enough at the top either. From what I have seen, the CMB carb's generally do not work particularly well with pressurised fuel systems either. They work best with (and are designed for) a float chamber. Second best is gravity / suction feed, but obviously this is not always practical.

I was told by a good authority on CMBs, that, to get an initial setting for the LSN, you need to take the carb off (so that you can see behind the shroud over the top of the tube), and at WOT, the point of the taper should be between something like 1.5 and 2mm from the actual hole in the tube. Next, adjust the main needle for optimum setting at WOT. Then adjust the idle needle for good throttle transition. This was for a CMB .45, but the carbs are much the same. Otherwise, as was said earlier, screw the LSN out so far that it's not really doing anything, then adjust it like a carb with no LSN.

My opinion - for what it's worth.....

Ian

 

[tmunn]

I feel kinda foolish now for not mentioning this before but i am using the Don Ferrete remote with the o.s inflight needle .Therefore there is no HSN attached to the carb.

Sorry for not being more specific.I only though of it once you guys started talking about the interaction between the HSN and LSN..

MY HSN is the o.s inflight needle valve.

I can unscrew the lsn and try it if that is still suggested even though i ma using the remote base and o.c needle.

The lsn is on the opposite side if my fuel inlet nipple obviously.

Thanks for all the help guys will try and be more specific in the future.

Terry

 

[Tofastformellow]

the standard valvola setup works flawlessly on 70% ...

i can stop my boat , it dosent ever stall ... drives fast and slow ...really well..

if it works great why change it ??

if its not the stock setup then i can see problems forming ... me i just cut the cowel on my sgx 21 to fit the onboard 3rd channel carby on.

on my FF21 it drove slow like a mono and went fast like a cut cat...

on my sgx21 , its so overproped that i have to drive flatout or it falls of the pipe easy... but still dosent cut out..just burbles back to the dock

Jason

 

[tmunn]

Once i get back out i will take the advice of some and try to make the proper adjustments with needle settings.

I am out 2 turns from closed on the lsn .I know there are many variables that dictate that such as nitro level and sea level and temp, but does that seem closed or open too far .It won't even kick at 1 turn out.

I think i will try it really rich on the lsn.

Thanks

Terry

 

[Marty Davis]

I feel kinda foolish now for not mentioning this before but i am using the Don Ferrete remote with the o.s inflight needle .Therefore there is no HSN attached to the carb.
Sorry for not being more specific.I only though of it once you guys started talking about the interaction between the HSN and LSN..

MY HSN is the o.s inflight needle valve.

I can unscrew the lsn and try it if that is still suggested even though i ma using the remote base and o.c needle.

The lsn is on the opposite side if my fuel inlet nipple obviously.

Thanks for all the help guys will try and be more specific in the future.

Terry

Using the OS Needle is fine (the best that there is in my opinion) instead of the normal HSN.

Brad gave some good advice about how to set the LSN to start.

Just be sure that the LSN is so rich that the engine will barely run on the stand. The go in just until it leans a LITTLE bit from super rich (barely able to run on the stand).

Then just go in a little each run until it will mill very well and will be great on the stand.

Also, be sure that you have the correct OS needle in the Ferette base. The one with the groove in the knurled end is the one that you want.

Marty Davis

 

[dwb2620]

Marty is correct about the needle. You need to use the needle with the groove in it. When I first got Don's needle base and the OS in-flight needle, I installed the needle without the groove. My boat would fire up and throttle just fine while on the stand. But when I would launch the boat it would either run 20 feet or 3 laps, no matter what I had the remote needle set at. ONLY when I put the needle with the groove in it did it run correctly out on the water.

David

 

[tmunn]

Went out to the garage and checked the remote needle and guess what ...I have the needle without the groove in the knurled portion in the base.

I will change them and then try that with being really rich as suggested .

Man i can be stupid and such a newbie... :angry:

Terry

 

[tmunn]

Well only had a chance to run 3 tanks today.I richened it as far as i could and almost so rich that it would not run ...good and blubbery on the LSN.I am out aprox 3 turns .Anymore it would not start, flooded itself and would not run.It seemed to like 3 turns out and it was around 75-80 degrees today.

I adjusted the HSN on the ferrete valve using the needle WITH the groove in the knurled part this time, out 4 turns

I did not touch the pipe length and a, still at 8.75" .

It seemed to take a long time to get up on Plane and get up on pipe.BUT i do feel it is very close to going it's fastest at WOT and there is less of an increase when I back the throttle out.

Perhaps now I can make small adjustments to the remote needle to see if there are any performance change ??

So some progress was made before I had to quit for the day.we were running other boats and then the wind came up.

The only thing i can compare it to is our miss vegas rtr hydro .our little .18 ,,,when you nail them hey lust pop up and go..

The ssp21 is very sluggish and takes a couple hundred feet to come up on pipe ir if you make a left turn or twitch the back of the boat with the rudder to get the R's up .That will help her come up on pipe.When it come to life it hauls pretty good and runs pretty flat.

I know it is not the boat but something i have setup incorrectly or am overlooking.

Here is my setup below .Could anyone tell me why it take so long to get up on plane and pipe.

SSp21 ..cmb valvola .21...ops3280...m440(tried many others)rear radio box,tyndal fin,30%nitro mccoy #9 plug.8 oz tank in the front.don ferrete needle. valve with needle that has the groove in the knurled part.4 turns out on hsn 3 out on lsn.

I hope i did not forget anything.

Guys I really appreciate your help via here, pm's, and e-mail.

Terry

 

[Don Ferrette]

Terry have you tried an X437 3 blade yet? You may be able to bring that LSN in a little as well, go an 1/8 turn at a time. Being too fat on the bottom can make a boat slow to get on plane. Also those little motors tend to like high nitro, I ran 60% in my 21's.

 

[Dan Hydro]

Terry have you tried an X437 3 blade yet? You may be able to bring that LSN in a little as well, go an 1/8 turn at a time. Being too fat on the bottom can make a boat slow to get on plane. Also those little motors tend to like high nitro, I ran 60% in my 21's.

The only problem for us with Nitro fuel is that to get the 60% will cost us approx $60 bucks a gallon.

 

[Marty Davis]

Terry have you tried an X437 3 blade yet? You may be able to bring that LSN in a little as well, go an 1/8 turn at a time. Being too fat on the bottom can make a boat slow to get on plane. Also those little motors tend to like high nitro, I ran 60% in my 21's.

Don is correct. Reduce the prop load if you are going to run low nitro and it will work fine, get up easily, etc.

Marty Davis

 

[tmunn]

Ran a few tanks thru today before the wind came up.i had the x437/3 and out rich on the lsn that it would hardly run.

I gave it a good hard launch and she went right up on pipe and would stay there until i backed out of the throttle past about 1/2.Then it would come off pipe and just lazily motor around and would only ocassionaly come back up if i twitched the rear or made it cavitate by turning left.

I was going to leave the Hsn and start going in on the LSN but then the wind came up.Would this be a good thing to do now start in say about 1/8 turn at a time on the lsn?

It has hardly any power at the bottom to 1/2 throttle.

Pipe is still at 8.75 and running mccoy 9 and 30% nitro(not racing)

seems to have good top end but no torque

If i am cruising along at 10mph and hit it she hardly will pick up speed.

The prop should not be the problem the pipe is as long as anyone else running this setup

Thanks

Terry

 

[Don Ferrette]

Like I mentioned previous, start leaning out the LSN an 1/8 or so at a time.

 

[tmunn]

will do next time out..got too windy today...

is this the correct fuel nipple for the .21 CMB VALVOLA.

I was told by a very knowledgeable member it should have a chamfer on the inner hole.

http://www.intlwaters.com/index.php?automo...=si&img=892