Track Tac

Getting rid of the 10.8 check

DynoDon

DynoDon

Moderator
I am looking to propose to AKRA for dropping the 10.8 check on the valve spring and only be concerned about the 18 lb check. Can anyone tell me if there would be any manipulation to the 10.8 if dropped that would be a performance gain? Wire diameter and spring coil spacing check will remain in the rules as they are. Reason I am investigating is ever since covid springs have been failing the 10.8 much more than the 18 check.
 
I think we will see rpm ramp up.

Lofting the valve can be controlled by the shape of the nose of the lobe. Valve closing speed is the critical thing.
Seat pressure is what controls valve float.

Are the failing springs already getting a pass?

If the springs can't pass the established test, raise the installed height instead.
 
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I guess I have to ask : if we keep the current wire diameter and coil spacing check with the block and the 18 lb check how could the spring be manipulated at the 10.8 check. 95Shaw. You think that a cam would be made to ramp it harder? If so wouldn’t having more pressure at the 10.8 take away from the 18 if we kept the above checks?
 
Apparantly this is already happening.
There are already springs that will not pass the existing 10.8 rule without manipulation.
Already talk about how to get those to pass.

Simplest is to increase the required installed height, making the problematic springs no longer an advantage.

What was the reasoning behind either of the checks to start with?

I'm talking 10.8 rule, and the installed height minimum.
Tech will be no less with your proposed change, except tech will have to make the call.


Like suggested, increase the height for the 10.8 check, and the installed height minimum.

Not going to be popular. Will make existing engines illegal.
Could just leave the rule alone, and toss the failing springs.
No more expense for doing it right to start with.
 
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Springs are problematic. If the 10.8 is legal the 18 is illegal. If the 18 is legal the 10.8 is illegal. Get either of those checks legal and the other is weak. Most of the dq’s I am getting calls about are the 10.8. I know for a fact through my own experience that I have set the 10.8 legal. After a run on the Dyno the 10.8 is illegal. Haven’t had that with the 18 check
 
I interpret the rule to be both must be less than the specified weight number at a specific height.

Doesn't say they have to both be exactly at the maximum.

The litmus test for any rule change is,

Will this bring cost to the racer down?

Will this bring more racers?

Will this make for better racing?


Easier to tech should be far down the list.
 
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95 shaw said:
I interpret the rule to be both must be less than the specified weight number at a specific height.

Doesn't say they have to both be exactly at the maximum.

The litmus test for any rule change is,

Will this bring cost to the racer down?

Will this bring more racers?

Will this make for better racing?


Easier to tech should be far down the list.
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Every time theres a rule change, price goes up. Never seen a rule change where it lowered the cost to a racer.
 
95 shaw said:
I interpret the rule to be both must be less than the specified weight number at a specific height.

Doesn't say they have to both be exactly at the maximum.

The litmus test for any rule change is,

Will this bring cost to the racer down?

Will this bring more racers?

Will this make for better racing?


Easier to tech should be far down the list.
Click to expand...
All of those are the reason I asked the question. Easier to tech has nothing to do with it. Disqualifying engines from money races over a check that MAY not be necessary is my question. SO, I am hoping that someone who understands cams can give me an honest answer as to if dropping the 10.8 check will cause problems. If the 18 check is in place and the wire diameter is in place, and the coil spacing is in place how can removing the 10.8 be a problem? Just asking guys, just asking!!
 
From the flathead days.

The difference between the various plate engines and unrestricted is the pressure of the valve spring exerted at the seat. This changed the rpm that the valves bounced on the seat. Of course, it also lofted the valve at a lower rpm, which is where the power came from on these engines.
Those cams biggest feature was the ramp profile which set the valve gently on the seat, making lofting the valve a viable possibility.

Right now, clone engines are rpm limited by those valve springs. Not from lofting the valve, but from controlling valve bounce at the seat, particularly the intake valve, which is heavier.
If there is more pressure at the seat, the cam profile can be more aggressive on the closing side, adding duration where the flow and velocity of the intake charge is the highest.

A search of coil spring construction will tell the factors which change the rate of a spring.
Wire diameter, number of coils, spring diameter, and free height are all factors.

The 10.8 check at the minimum installed height is, in fact, a check of maximum seat pressure. Removing this check opens a world of possibilities.

Opening this up will redouble the cries for billet rods as that will become the limiting factor for rpm.
 
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Right now, the only way to crank rpm higher is by lightening valvetrain components, or increasing spring seat pressure.

Lighter valves, lighter lifters, lightened retainers, pushrods, etc are a means of effectively increasing seat pressure by reducing the load being controlled by the spring.

The cam profile may already exist, just needs more valve control to raise rpm limit.
 
I say keep the 10.8 and make the cheaters correct there spring problem. There not grinding enough off the spring and if there so called growing with time then swap springs. All there trying to do is increase the rpm on these engines to there advantage this will just be another way for the top dogs to make a rules suit there needs just my opinion.
 
Just another reason I'd like to see BOTH the 10.8 and 18# checks done away with. Go back to spring dimensional checks like the flathead had -- You've already got most of them in place, including number of coils and spacing to help. Builders are using springs that barely meet the specs (or are slightly out of range) just hoping that they'll be within spec by the end of the race. With them growing after a heat cycle, a new concern has arisen, with not meeting the 10.8 rule. Seems you can heat, shrink, grind these things over and over, but they keep changing in length - and when you start with something that's on the edge to begin with, big surprise, it fails tech occasionally. That's a risk that many builders (including some big named ones) are willing to take. Then consider than many builders don't size their springs at all -- they trust their spring supplier and don't question how they may have manipulated those springs to get them to meet the rules PRIOR to selling them. It's my thought that using weights to tech the springs is what has caused all of this disparity and evolution of springs. Put strict measurement techs on them that are easy to enforce simplifies the situation. No rpm gained and no more expensive tech tools to purchase. Problem addressed without much fall-out to racers or builders.


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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
34 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
CarlsonMotorsports said:
Just another reason I'd like to see BOTH the 10.8 and 18# checks done away with. Go back to spring dimensional checks like the flathead had -- You've already got most of them in place, including number of coils and spacing to help. Builders are using springs that barely meet the specs (or are slightly out of range) just hoping that they'll be within spec by the end of the race. With them growing after a heat cycle, a new concern has arisen, with not meeting the 10.8 rule. Seems you can heat, shrink, grind these things over and over, but they keep changing in length - and when you start with something that's on the edge to begin with, big surprise, it fails tech occasionally. That's a risk that many builders (including some big named ones) are willing to take. Then consider than many builders don't size their springs at all -- they trust their spring supplier and don't question how they may have manipulated those springs to get them to meet the rules PRIOR to selling them. It's my thought that using weights to tech the springs is what has caused all of this disparity and evolution of springs. Put strict measurement techs on them that are easy to enforce simplifies the situation. No rpm gained and no more expensive tech tools to purchase. Problem addressed without much fall-out to racers or builders.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
34 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
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You might find this hard to believe but what I am about to tell you is the truth. A while back I was asked by AKRA to see if I can come up with an uninstalled heights that would be suitable to eliminate the weight check. Every time I would find a spring that was within the dimensions of 18 pounds it was only a short time longer until another one come along that was too tall to meet the spec that I had come up with. And still be within the 18 pounds. I actually gave up after two years of trying to find that magic number.
 
Dump the spring pound checks and go with minimum installed hieght as is .850 then use the already specified checks for the rest .
Apparently a rule change is coming down the pike anyway .
After two years of not finding the perfect spring/ pound combination
Too meet current rules , just eliminate the problem.
The mfg will produce whatever's needed .
 
No rule change is coming down the pike. Just a simple question was ask. If I could get a conformation as to my original question then you might see one but it doesn’t look good so far.
 
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A simple question with a complicated answer .
------Right now, clone engines are rpm limited by those valve springs. Not from lofting the valve, but from controlling valve bounce at the seat, particularly the intake valve, which is heavier.
If there is more pressure at the seat, the cam profile can be more aggressive on the closing side, adding duration where the flow and velocity of the intake charge is the highest.------
Post3&6 imho cover it .
answer yes . There would be an advantage
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If it meets at 10.8 and fails at 18 and vica versa . Why not change one of those parameters .
Answer they will then push the limits with a different spring .
 
DynoDon said:
You might find this hard to believe but what I am about to tell you is the truth. A while back I was asked by AKRA to see if I can come up with an uninstalled heights that would be suitable to eliminate the weight check. Every time I would find a spring that was within the dimensions of 18 pounds it was only a short time longer until another one come along that was too tall to meet the spec that I had come up with. And still be within the 18 pounds. I actually gave up after two years of trying to find that magic number.
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But see, Don, this is going about it backwards. Take a given spring (call it known stock sample or whatever wording you choose) and spec it. Then force the manufacturers/distributors/dealers/builders/racers to comply with the rules....not the other way around. Of course the springs will keep changing if the manufacturers know that the rules will change to accommodate them.
 
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