Carb CV spring changes

[rxrider]

Sorry to hear BigDog05, warm weather sucks, we have cold weather but still very little snow. We need some more as well.

 

[tonykof]

rxrider: Thanks, sled back together with 132.5's. 10 days ago we had at least 2 1/2 ft of snow in the mountains. Last Saturday it was 48F and has been warm and rainy all week.

Hopefully we will get more snow soon.

BigDog05
Did you have a chance to test this anymore? Did it help to lean the mains?
tony

 

[BigDog05]

tonykof: The springs from hurricane performance worked great to get rid of the pig rich low speed and bog on hole shot. But they were just too lean in the midrange for the Bender rear mount.

Right now I'm running 130 mains, with 17.5 pilots and fuel screws 1.75 turns off seat. With 130 mains I'm able to run around 400-500 in pitot jet depending on temps. Last week end it was around 32-36F and I was running a 500. This was at 12 PSI boost. At 55-70 MPH I'm at 3-5 PSI boost w/o any load and I'm around low 13's on air fuel. This is between 2200-3000ft elevation. This is with stock carb springs.

rxrider was correct when he suggested the smaller mains so the smaller pitot jet would help the midrange. I tried raising the needles one notch and it got real rich at slow speeds again, flashing 10's on the AEM.

I also tried the Hurricane springs at one notch rich and it was terrible.

I'm going to try 127.5's next, but we have been having great snow and don't want to mess with it now.

I think that one of my problems was running straight 100LL Avgas the past couple of years. That runs very lean. With 100LL I could run a 400-500 at WOT. But the 135's were so bad down low. This year I run 50/50 or 60/40 112 Sunoco and 93 Sunoco. With the 135's and Sunoco I had to run over a 700 in the pitot for WOT. I drilled a couple of jets that were 800 and bigger.

 

[tonykof]

Yeah I'm struggling a little with the "turbo" springs.. Same as you.. My needles are raised one notch, it's rich when I just touch the throttle 11 or so (gurgles rich when I slam it to the bar) & midrange cruizing is probably marginal at 14.5-15.1... I'm pretty sure I could lean up the btm by putting the needles back in the stock position but then I'm pretty sure I"ll be lean at cruizing.. I'm not sure what to try next for springs as like I said I'm going to have to put the needles back in the stock position to get my btm a/f back in check.

I must really be a bone head cause this CV spring thing is really throwing me... I wonder what would happen if I went softer springs would that richen up mid..??

present set
17.5 - 1 3/4 turns
needles #3 (stock)
turbo springs
135 mains

idle 13.4-14.5
light 10.8-11.5
mid cruzing 14.2-15.2
wot 11.8

 

[BigDog05]

I tried that. If I remember correctly I tried green and silver springs.

It did richen up the mid's but made the low speed and hole shot bad.

If you were cruising at 2 or more psi of boost and hammered it, the light springs were great. But from a dead stop and hard acceleration from only a couple of mph it would burrble and bog, and then clean out and take off.

 

[BigDog05]

I realize that each sled is different, but if you are around 10-12 psi of boost, the 135's seem big w/o a pitot jet. If I blocked off my pitot jet all together I think I could run 127's or smaller and still get under 12 at WOT.

Even though the main jets control mostly WOT, I believe they also have an effect on a holeshot situation where you have not built boost yet and are just pouring in gas.

 

[Ted Jannetty]

Guys I hate to tell you this but Springs are not a tuning device, they are there to react to atmospheric pressure at the inlet of the carbs.

When you change out the Factory Air box for a high flow intercooler it is the same as taking the air box off and you must compensate with lighter springs so the slides will open fully.

The Float bowl signal is where the tuning needs to be done and it is complicated to explain but I have mastered it.

Honestly Tony if your sled sounds good and drives good leave it alone and drive it, it sounds to me like your stressing over numbers on your wideband.

Sometimes too much information can be dangerous. LOL

Ted.

 

[tonykof]

Guys I hate to tell you this but Springs are not a tuning device, they are there to react to atmospheric pressure at the inlet of the carbs.

When you change out the Factory Air box for a high flow intercooler it is the same as taking the air box off and you must compensate with lighter springs so the slides will open fully.

The Float bowl signal is where the tuning needs to be done and it is complicated to explain but I have mastered it.

Honestly Tony if your sled sounds good and drives good leave it alone and drive it, it sounds to me like your stressing over numbers on your wideband.

Sometimes too much information can be dangerous. LOL

Ted.

Okay........
So putting aside the "too much information can be dangerous" line...
Your saying put in lighter springs & rejet around them for proper tuning...?

BTW: My sled IS presently rich on the btm... not just #'s on the wideband...

 

[Ted Jannetty]

Guys I hate to tell you this but Springs are not a tuning device, they are there to react to atmospheric pressure at the inlet of the carbs.

When you change out the Factory Air box for a high flow intercooler it is the same as taking the air box off and you must compensate with lighter springs so the slides will open fully.

The Float bowl signal is where the tuning needs to be done and it is complicated to explain but I have mastered it.

Honestly Tony if your sled sounds good and drives good leave it alone and drive it, it sounds to me like your stressing over numbers on your wideband.

Sometimes too much information can be dangerous. LOL

Ted.

Okay........
So putting aside the "too much information can be dangerous" line...
Your saying put in lighter springs & rejet around them for proper tuning...?

BTW: My sled IS presently rich on the btm... not just #'s on the wideband...

fuel Screw and Pilot are for Idle to 1/8 throttle
Needle is for 1/8 to 3/4 throttle
Main Jet is for WOT
But they all work hand in hand
Float bowl pressure from the turbo affects everything.

I call it transitional fueling, how hard and how fast the pressure reaches the float bowls determines the fueling in that area.

Changing the size of the charge pipe, length of the hoses, tying the float bowl signal in with other sources can all affect fueling in different areas of drive ability.

 

[tonykof]

Thank you Ted, this actually makes sense to me.. not sure how/what I could really change on my sled to get the desired outcome but I do get the concept...

I'm done

 

[capri]

I am having the exact same problem as you are. Today i put in #15 pilot jets and turned the fuelscrews to 3 turns out to compensate the smaller jets at idle. The idle is good,and the rich bottom is slightly better now, 12-12,5. My thought was too rise the needles to fix the lean middle(14-16) too, but i guess that it will run rich in the bottom again if i doo that..

I run the stock springs,but i have hard to understand how a harder spring can solve the lean mid without richening up the bottom more?.

 

[Ski-Dooin' it]

just an interesting thing I hav elearned for all the people trying to tune around the dangerously lean midrange on the bender setups with the pitot tube.

I run my cutom kit with a system like the bleeder valve on the pitot tube.. it allows for nice tuning. The crazy lean midrange lean spot you see is because, cruising at the boost transition zone, your carbs are seeing a little boost. but the bleeder valve is not alloing the small amount of pressure ot reach your flaot bowls, so your getting a lean spot. I tried to compensate for overly large jetting with my bleeder valve WAY open, then i get a crazy lean spot that will actually pop really bad on me and stall the sled if I hang in the midrange. drop mains so you can run the smalles possible pitot tube jets.

as far as springs. I need to try some hurricane ones. I have a nice lean idle like it should be, but when I whack the thing to the bar from idle I get a little sputter as the vaccum drops around the slides and opens to fast.. if i ease in to the throttle my afr stays nice.. just when its sudden it gets all angry.

 

[rxrider]

Right on Ski

 

[Ski-Dooin' it]

I just figured I could try and explain my take on the bender midrange lean spot. I have the ability to go from closed pitot to a gaping leak with a few twists of the screw.. nice thing is you do about 1-2 clicks per 1000 feet depending on temps and such.. makes keeping the rx1 dialed in SUPER easy for elevation.

RXrider.. my low end sounds kinda like the one you had.. stab it from a stand still and then it would just stumble for a second then come on like a freight train. but if ease into it works great and afr's stay good... so dont want to mess with needle position.. sounds like hurricane springs might be in my future.