nothinbetr2do

hi guys. i'm not sure if you will remember this build http://www.rcuniverse.com/forum/m_91..._1/key_/tm.htm well, after the winter and me working on other projects. i'm finally ready to get this boat going. since it is my only build and first time having to mess with tuning a pipe. i was wondering how or when you tune the pipe. is it first the carb, then the pipe? right now i have the pipe set at 13" to start with, this is what i was told to do by bh hanson. so far the boat has not been ran, and i'm wanting to know what to tune first( carb or pipe) or do i do them together some how? thanks for the help

nothinbetr2do

just a note. i have other gasser trucks and buggies, so i can tune the carb. it's just i never had to deal with a pipe to. i just want to know the process. thanks again

dicko

Tune the carb, then shorten the pipe in small (1/4") increments until you notice that when you corner at wide open throttle the speed drops off, then back it out 1/8" at a time until you get the speed & power back. Once you have the length right, cut off the excess header inside the pipe so that 1/2" is left poking into the pipe behind the rear cooling O-ring. This way you can have some room for adjustments as changing props may need slight pipe adjustments, and if the pipe works back while running you won't lose your cooling of the O-rings.

nothinbetr2do

right on brother, thanks

that there should be a sticky [8D]

dicko

Yeah, I've written it a few times now.

nothinbetr2do

well maybe a sticky then, let's see who else chimes in [sm=thumbup.gif] good info is always good to have on top of the boards

nothinbetr2do

please delete, double post some how

nothinbetr2do

hey, maybe we can call this me, my carb, and my pipe. and then list all the things a new gas engine and exhaust needs, to get running, including a run it period and then tuning

Dreamin Hemi

This is a very popular topic and question and I think it is worthy of keeping it a "sticky" myself as this question does come up very often. Please feel free to contribute to make this a great thread! Enjoy...

danielplace

Good advice. Just one thing, start long of coarse but you must cut the header initially and actually as you squeeze it in too as it will effect the results of each new setting. Any poking in the primary cone will create anti reversion not allowing it to supercharge as well.

Ron Olson

My Feedback: (1)

To me so far it seems like there is a third equation to the mix, the right prop. The carb seems to be the easy part as that can be checked for the right setting by reading the plug. Too large of a prop can place an undue load on the engine and too small will make it rev too high.
Sometimes only the driver can really tell when some pipes are working as I've got one that comes on so smoothly I wouldn't know if I wasn't driving. One that hits the band hard is more noticable to others.

I'll sit back now and wait for Scott Schneider to chime in. He's one of the best engine Guru's on this site.

Scott Schneider

Ron ... you assume a lot Lol
All I will add is the approach used when personally setting up my own boats.

Do this long enough we get a good idea what pipe lengths are on the long and short side ... so I will start long allowing engine to be calmer in power output and have a broad power band.
Next ... I will start the prop search for a prop the Hull likes for Handling, Launching, Milling Etc.
In this equation is also a prop the engine can pull well having again good launch, milling attributes etc.
* Once narrowed down to a few prop choices the hull & engine likes will start looking at maximizing performance of the engine and pipe.
Now I will start shortening up the pipe getting engine to run like a race engine should .... Set pipe so engine has a good on pipe hit in the upper midrange. Generally some of the more aggressive props that were contenders early on no long mill well due to loss's in torque with the shorter pipe setting, this not an issue because what I am looking for is MAXIMUM engine performance and peak RPM power.
Again ... generally the more conservative props from early testing seem to work best overall but in a lot of cases will be a tad slower.
Prop cupping and modifications is connecting the final pieces of the puzzle.
If the prop/props from original selection are having engine rev too high, don't have the speed other props may have had will start reworking the blades to increase engine load and increase efficiency.
( why we see so many guys now buying custom profile props )

Have found approaching the tuning game this way you end up with a far more consistent running boat ... Hull is happy because you have matched the prop design/profile to what works best ... And engine is performing at maximum output.

** Biggest mistake IMO most boaters make is choosing what they feel is the idea prop by listening to others or whatever reasons and then proceed in altering engines power band with a non optimized pipe setting just so they can run that prop [:@] You end up maybe running well but you have compromised handling and engine performance .....

In the end tho you very well may need to run that bigger prop on a slightly longer pipe setting to get hull all sorted out ... But make no mistake about it, those who understand and use all the tricks of tuning generally are the guys with the targets on there backs everyone else whats to beat [:@]


JMO nothing more ....

mickieb49

Hi all, there sure seems to be alot of different idea's on what is best but can anyone give approximate Carby Needle settings for a Zen 26 with a 257 carby? I am very green with gas boats so some help ould be much appreciated.
Cheers Mick

Scott Schneider

Mick,
Start out @ 7/8-1 turn on HIGH and 2 - 2 1/2 low.

mickieb49

Thanks heaps scott,
May finally get my 2 jetsprints and cat up and running now.
Mick

nothinbetr2do

great, this is awesome info. that's what i was looking for. thanks to you pro's for posting it for all to read.

but while i have you i have a rcmk evo, with a bh hanson pipe. if you check out my link in the first post, where should i start? let's say prop, carb settings, and pipe length setting
thanks again to all the pro's, for taking the time to do this

Scott Schneider

Stock EVO ... using 90* or 100* 7/8 header measuring in a straight line mid header at manifold to START of rear cone ( Peak of cones on a zero band / end of band if a band pipe ) you want to start @ 12 1/2" and come down as you test likely not going shorter than 11 1/2"

The supplied Wt929 carb @ 1 1/4 on H and @ 1 3/4 L

Props if setting up surface drive will be along these sizes of Propshop & VooDoo: 6516/3 7016/3 6717/3
ABC 2514 2516 2614 2616 2 or 3 blades
Prather 270 275
Octura x467 X470 X472 X670 X470/3

nothinbetr2do

super. thanks alot for the info

fritzz13

im setting up a new t-boat,all wood,55 inches,with a stock zen and a 257 carb,what would you suggest for gas to oil mix,and what prop do you suggest.

Ron Olson

My Feedback: (1)

Gas to oil; 8 oz. of oil per gallon of gas. Use good oil like Honda HP-2 or Amsoil Sabre.
Sorry, I don't know of a hot prop for it.

Willow991

As a rule a shorter pipe = more bottom end and a longer pipe = more top end.

When tuning. Always run the maximum amount of fuel through the carb as possible. 2T engines prefer to run cooler and fuel is cold so more fuel = cooler running temps which = more power .

When tuning for top end start off with the base settings and run the boat at full speed/full throttle, richen the high jet each run until the boat runs a little rich up top, then just back the jet off slightly until it runs clean.

Same with the low jet but you can tune the low with the boat stationary.

ryan_t888

Other way around.
Shorter Pipe - Shorter Wave Length - Higher RPM

Ryan

GEORGY

How do you "read" the plug? Dark colour is rich? & light colour is lean? What is ideal? Will running at high altitude affect the colour? We race at 1700m (5600 ft) above sea level here in Johannesburg, South Africa.

George

Scott Schneider

Yes plugs operating temputure and mixture effecting carbons color upon plug will be the same at higher altitude also.
* Just keep in mind for good plug reading to be consistent engine operating temperature needs to be up into the 150/170 degree range.

madmorgan

My Feedback: (2)

any responses on plugs like platinums etc or will a good ole ngk r be just as good? in other words is paying for that "platinum "name on the box is it a waste. i only ask because i bought some platinums for my camaro and ended up having to get rid of them because of spark gap etc .