valve springs

[collinsdad]

got a quick question here; what would too stiff of valve springs do? i cannot get this motor to rev up?

 

[DARK AGE 53]

I don't think your springs are the problem, as for too stiff of a spring the only thing I can think of would be your cam lobes will wear sooner.

 

[collinsdad]

thanks for that im still looking for an answer to this problem,coil should be here today

 

[Leftythenub]

what cam are you using?

 

[collinsdad]

super dyno x cam with a 275 lift with stock geom.

 

[mmisterbungl]

and what springs?

 

[collinsdad]

26lbs

 

[mmisterbungl]

i ran that same exact cam and springs and got around 7500rpm with 5:1 gear ratio.

 

[collinsdad]

i still cannot get 4500 rpms out of this motor,any ideas why?

 

[65ShelbyClone]

got a quick question here; what would too stiff of valve springs do? i cannot get this motor to rev up?

Too much spring is far more likely to damage something in the valvetrain than negatively affect RPM. Your problem is probably related to either fuel, ignition, or some other mechanical issue.

 

[collinsdad]

do you think the coil can be weak?or do they just work or not work??

 

[65ShelbyClone]

If the spark is a strong blue color when spinning the engine, then the ignition is probably good. I don't recall off-hand what the coil testing procedure or values are. Trying a known good spare could rule it out if you have one.

 

[olajoe808]

got a quick question here; what would too stiff of valve springs do? i cannot get this motor to rev up?

Prevent the motor to rev up, break the rockers, bend the pushrods/rocker studs, wear down the cam lobes, or worse case kill the motor.

 

[collinsdad]

the springs will prevent the motor from reving? i can on get like 4500 rpms

 

[olajoe808]

if it's too light= valve float. too heavy= more work for the motor. leave everything the same and use a weaker spring.

 

[collinsdad]

they told me to use the 26lbs with the cam,

 

[65ShelbyClone]

Prevent the motor to rev up, break the rockers, bend the pushrods/rocker studs, wear down the cam lobes, or worse case kill the motor.

That would require the valvetrain to be absorbing all of the engine's output power at max RPM. :shrug: Keep in mind that the valve springs do return energy to the cam when they apply force on the trailing side of the cam lobe. Of course, they apply less and less as RPM increases because more of their stored energy is used to accelerate the valvetrain into the closed position. Even 10.8lb stock springs will take a BSP engine into the 5500RPM range and 26lb springs aren't that stiff IMO, so I really don't think the springs are a problem in this case. Just my opinion, not absolute fact.

 

[collinsdad]

so what yoy are saying is that the stiff springs would put to much pressure on the cam causing less rpm?

 

[olajoe808]

That would require the valvetrain to be absorbing all of the engine's output power at max RPM. :shrug: Keep in mind that the valve springs do return energy to the cam when they apply force on the trailing side of the cam lobe. Of course, they apply less and less as RPM increases because more of their stored energy is used to accelerate the valvetrain into the closed position. Even 10.8lb stock springs will take a BSP engine into the 5500RPM range and 26lb springs aren't that stiff IMO, so I really don't think the springs are a problem in this case. Just my opinion, not absolute fact.

I know it's not the springs. they not going to sell this guy the springs tell him it works only to set him up for failure. my post is only from my experience and to answer the original posters question. now there's questions coming out of questions. he should state exactly everything that has been done to the motor before trying to get a better trouble shooting going. the 26# springs he using is for 8000+rpms. who knows what this guys is running, a flat tire, 3.0 gearing. :shrug:

 

[collinsdad]

ok this is what i got billit flywheel,rod.010,ss valves,pushrods,flattop,010 headgasket,15cc head,26lbs springs,super dyno x cam,22mm mikuni carb(never again)fuel pump,this motor wont turn 5000 rpms what the hell is wrong???