Tuning problems - K4.6 savage

[stevo1957]

Gidday,

I have a new Savage SS 4.6 and am having a tuning problem.

I returned needles to stock and started again. I have the low needle about right, in terms of the "pinch test" etc. If I richen anymore, it will bog at acceleration, just before it changes into second gear. The high end needle may be a bit on the rich side, but I like to maintain my tunes this way to prolong engine life.

All my Savage tunes are done at 1/2 tank level of fuel. I am running 20% nitro.

I try and maintain temperatures at about 240 degrees F when the tank is just about empty.

I have sealed the backplate and carby and have checked for air leaks and replaced fuel lines.

However, my problem is this:
When I bring the truck in to a standstill after a wide open throttle run, the revs will stay high for about 4-5 sceonds before they drop down to a steady idle.

Linkages are free and carby gap is set at about 1 mm.

I have researched considerably online for tuning solutions and have spent considerable time trying to resolve this issue. None of my other engines do this.

Can you please suggest what may be the issue and how I can resolve, or is this just a particular characteristic of the K4.6 engine?

I would have put 1 - 2 litres through the engine so I would have thought it was broken in by now and would be easy to get the final tune right.

I have not adjusted the mid needle - it is still flush and the slot is oriented in the "11 o'clock / 5 o'clock" position which is how it was "out of the box".

Any assistance you can provide would be appreciated.

Thanks,
Steve

 

[skoal bandit]

my ss4.6 w 3 speed runs the same as you described. i run 30% nitro,about a gallon thru, i get a good tune temps/smoke o.k! great power, no binding anywhere and i get the same thing after a wot run. i am no newbie, and since it runs great with proper smoke/temp, i just chaulk it up to this particular engine. i could be wrong but there is also another 4.6 i run with and it does the same also!onder2:

 

[rossb]

When I bring the truck in to a standstill after a wide open throttle run, the revs will stay high for about 4-5 sceonds before they drop down to a steady idle.

Sounds like a lean condition to me. Does the idle stay high if you apply the brakes?

 

[SMaxxin]

I have a 4.6 with the 3 speed, the only time mine does this is when it's about to run out of fuel (leaning). My running temp is 240-245 it will go up 5-10 degrees when it's almost empty.