Valve float too early? 18lb springs.

[ForceFed86]

How often do you all replace springs? I'm running into what feels like valve float around 5600ish lately? Seems ODD. Springs are about a year old, but the engine only sees a handful of 300ft passes. Maybe 30 on it total. Seems Odd as this head assy was on the last engine and would rev out to 7000 without issue on a clutch setup. Juggernaut on it now. Just curious where guys are seeing valve float. It's the stock cam (hemi motor with non-hemi head) with 1.3 rockers. I tried removing these as well, and valve flat did not change. I have a set of 22lb springs on order. Curious if I should go higher.

 

[anickode]

Have you put it on a stand and revved it to max? While torque converters widen your perceived powerband, they sacrifice a lot of power (up to 30%) and it could be that with a load on it, the engine simply doesn't make enough power past 5600 rpm to overcome the losses and accelerate any further. Torque converters are definitely faster out of the hole, but they sacrifice a lot of top end to do it. That's one reason they simply don't run them on race karts.

Valve springs also wear out over time... Contrary to popular belief, they don't soften. They actually stiffen, but also get squished and lose some of their uncompressed length, which makes them behave as a softer spring in a poppet valve scenario. Could be a low grade spring that's just reached its lifespan. Stuff wears out exponentially faster on a built engine.

 

[ForceFed86]

I do. I'll give that a shot.

Would you bother with a 22lb or go to something heavier? This new Juggernaut TC is "supposed" to not slip and be capable of 8k+ But as you say I may not be making the power to pull through it. It's odd though because I have a 12t/80t setup with a 15" tire.

With the clutch and a 65t rear sprocket installed it would rev past 7k. I didn't take it there much because it didn't make power that high. But I'd like 7k or so out of it if possible. Figured this gearing would be more than enough mech. advantage to get it there! May just need more umpth as you say!

Appreciate the response!

 

[anickode]

Any claim made that the juggernaut doesn't slip is a flat out lie. It is the inherent nature of a torque converter/belt drive. There is friction loss, period.

 

[ForceFed86]

My big comparison and argument for converters is the junior dragsters. Or snowmobiles...etc. I can't justify the $ for one of those converter setups and I get they make a ton more power and can stand to lose a bit due to drive losses. Still for my application I'd think a properly setup converter should dominate.

Def. wouldn't mess with it on a kart track, im drag racing mini bikes to 300ft. I just cant stand how lazy the clutches are off the line. I've tried alot of them! dual disc cheetahs, hillards, max torques etc... All great once locked up and going. But all horrible from a dead stop.

 

[anickode]

I'm not saying it's not the right thing to use for drag racing, only that there are other considerations involved with a torque converter.

 

[ForceFed86]

Oh no, wasn't claiming that... I'm clearly wrong, as I'm getting gapped by all the clutch guys now! lol. Just didn't want to give up... and am always looking for ideas to improve the converter setup. Appreciate the help!