crowdie

Hey, My savage 21 has the dreaded half tank lean, and I was wondering what I can do to stop it? I am gonig along the lines of changing fuel tank as this one has the primer and Ive shortend fuel lines.
WIll the 4.6 fuel tank stop this lean? What will I need to fit it?
If not, what tank will? Thanks

twomanytoys

The 4.6 tank will not stop the half tank lean. I wrote a post on the half tank lean. The biggest cause is the stock pipe and make the fuel line as short as possible. You actually have to turn the carb nipple and face it to the tank and go direct from the tank to the carb. The line should only be about 4-5 inches long. A better pipe will also help out greatly.

sparky 25

I have a 4.6 x ss and the tank has not got a primer,

i was unaware of this problem with savages, only ever had this problem on my cen gst,

maybe the primer it letting out some tank pressure,

ive run about 12 tanks on my savage and it empty`s the tank each time before stopping

maybe the change of tank will help this,

here is a few pics of how my fuel line is routed

hope you get it sorted

crowdie

Thanks for the replies, sparky - that is how mine is linked, but the tank on the savage 21 has its little nib at the bottom of the tank to collect fuel.

Argess

You can make a great improvement easily by merely shortening the pressure line. I understand the theory behind it. Twomanytoys has found further success in shortening the fuel line. I fail to understand that theory, but iot does work. I matched his success with my OFNA buggy. Mind you, it wasn't bad to start with as I had already shortened the pressure line. I suggest you try his method (but shorten both lines) first.

Some engine and pipe combinations seem to suffer from 1/2 tank lean more than others. If you still have trouble, I have a method that is easy and cheap to do:

http://www.rcuniverse.com/forum/m_74...tm.htm#7496172

There are more complicated methods involving diffferent tanks and tank locations, header tanks, etc., but if line shortening doesn't work, the uniflow (with 1-way valve) mod will. No need to go crazy with fuel tank and header tank mods to fix this.

twomanytoys

Here is what the shortened line should look like.

alpinestar

ofna tank mod... just changed mine & glad I did.

sparky 25

I had the ofna check valve fitted to my cen gst and i must say it did work very well,

But the only problem i found with mine is that the pressure in the fuel line was so great

that i had to run the truck really lean or it would not run very well,

leaving me with two burnt out pistons and liners within 4-5 gallons of fuel,[&o]

which at the rate these large nitro engines eat fuel was not very long run time

maybe the smaller nitro engines are fine with the ofna valve,

but for me i will not be using this mod again

BudBud

It cuts it down a lot.... the stock Hpi pipe delivers the poorest fuel pressure of any pipe I have run... like they said, just try clipping the lines as short as possible. Shorter lines have less friction for the fuel to be pushed through. At the minimal pressures these guys work on, the difference is huge. Glen

SAVAGEJIM

Helz yeay! This is what I did for an ofna tank mod, no more half tank lean, EVER!

Additonally, each tank is more than 300ml, so run times are breaking 16min in between fill-ups!

crowdie

wow, I will definatly try and get these lines as short as possible, I am willling to try anything to get this sorted, as tuning is just impossible because of it. Do you think a new pipe will be needed awell? I'm not sure where I am gonig with my upgrades for this savage.. I will have to sort this lean out first, get it tuned right and then look into reverse module and a XL steering servo

twomanytoys

You dont need a pipe but it would be a good idea to get one. Not only will it decrease the lean issue to about none it will also give you alot better power. The Losi HT pipe is a great cheap pipe and it works awsome. You can usually get them from ebay for about 15-20.00.

Argess

Sparky 25....take another look....it isn't just a check valve in the pressure line. By the way....I lived just outside Derry once upon a time....1964-1966.