Recommended Carb Settings?

[millerracer]

Anyone have a typical recommendation on carb settings for me..

I currently have it set at 2-1/4 for break in and seems fine...

I have been told 2-1/2 to almost 3 by a friend, but he might not know.

It is an HPI 15fe, stock with purple head in an RS4-3.

Thanks!

 

[NCNitro]

If that has the single needle carb you are going to want to get rid of it asap. You will find if it is set to run good at speed, it will idle like crap and stall often. If you set it to idle good, under speed it will run like crap. I know they are hard to find but if you can locate one the OS 10e carb is the way to go for that mill.

 

[millerracer]

well - it idles like a champ right now - at 2-1/2 turns... so what "should" it be at speed? over 3?

 

[NCNitro]

I wish I could tell ya, but I removed that carb off mine almost immediately, and really don't remember what my settings were since it was so long ago, sorry.

 

[Plaidfish]

Keep in mind you aren't dealing with something you can "set it and forget it"...you will be changing those needle settings whenever the temperature, Humidity or barometric pressure changes....all those factors will affect the air to fuel ratio your engine needs......tuning is something that drives alot of people away from nitro......I've seen many people get frustrated and start saying "it ran perfect yesterday"......there is a definate art to tuning and once you get the ear for how your mill should run it's a blast......I tune by sound mostly..I use the temp gun just to see whne the mill is up to temp and just check it occasionally.....as long as your mill isn't lean bogging you're usually pretty good on the temps....I'm just over 14 gallons on an older P5 and it still screams like a rapped ape when I get on the pipe......

 

[millerracer]

Thanks Plaid-

I am pretty experienced with racing carbs and very familiar with several adjustments that this simplistic carb doesn't have. But one thing that is consistent with all carbs in racing or for hobby is a "baseline" to start with, which is what I'm looking for. I dug up HPI's recommending starting position of 3 turns, but that is pretty rich and it really isn't digging it, so I thought I'd ask people who might have played with this particular carb before.

Every racing machine I have driven I have used seat of the pants to tune... as well as very expensive data acquisitions systems to back it all up and find little things that you might be able to feel.

I certainly wish I could change the needle clip position or pilot and have a main jet and high-speed adjustment as well... but it is what it is

I can diagnose a lean bog and rich conditions - The only thing I'm frustrated with is no one seems to be able to answer my question - What is a good baseline?

Weather conditions and adjusted altitude will make the adjustement change 3-4 points maybe.... not 10-20, so my baseline will still keep it relatively safe once I find it.

 

[HeartBreak]

I guess the best answer is, there is no true end-all-be-all baseline setting. Manuacturing differences, in themselves, are enough to cause one carb to tune differently from the next, even if they are from the same assembly line.

The setting that comes in the book is good enough to get it to fire, and is based on the average of the carbs they have tested.

 

[FastEddy]

HeartBreak has the proper answer.
I have has 2 engines with serial numbers one after the other. The settings that made them run the same were totally different. When you look at the small size of the carb parts the smallest difference in manufacturing make a huge change in what your calling a baseline setting. The baseline will be for that particular mill and no other.

 

[millerracer]

The setting that comes in the book is good enough to get it to fire, and is based on the average of the carbs they have tested.

^^ That is exactly what I was looking for... and I completely get the "good enough to get it to fire" thing. I had my car out today for the first time... it seems to like about 2-3/4 but is still on the tail end of breaking-in... just started to free all the way up after about the last 4 tanks.

Thanks for the help.