Stiffer Valve Springs?

[mk3supreme]

Is it really neccesary to use stiffer heavy duty valve springs? I am trying to make around 400-500hp. But I hear you don't need them and the same for extra light valves, Someone help please cause I need to get my head redone because of my rebuild and I want every thing done right the first time around.

 

[MDCmotorsports]

IMO they aren't needed untill you go over 400hp.

If you do decide to go with them, buy Ferrea.

 

[mkIIIman089]

I don't quite understand the benefit to having stiffer valve springs at higher HP levels. Essentially are they needed simply to make sure that the valves seal properly under the much higher stresses at hundreds of HP over stock?

 

[IJ.]

Colin: Usually to get more HP you'd turn the motor faster so stiffer springs are needed to keep the valves under control but in our case we turn the boost up.

This in turn acts on the back of the Intake and tries to unseat the valve add to this the stock springs have very little seat pressure even when new and you can run into problems.

At stock boost levels no probs!

 

[mkIIIman089]

Okay, that's what I was thinking. I knew about it for higher RPM applications but I don't actually hear about many people doing it to motors with stock rev limiters. Got it now though! Thanks IJ!

BTW, with going up to a harder spring is it a good idea to get better retainers and such as well. As not to stress the stockers too much with more then they were designed for?

 

[siman]

Out of the blue some people found out that Comp Cams has a valve spring kit for the chevy v8 that fits our 7m heads.

http://www.powerandperformancenews.com/store/merchant.mvc?Screen=CTGY&Store_Code=CC&Category_Code=SPRNGSI

Part # 975 ( the - dash then the number means how many in the package)

so 975-1 is ONE spring, where 975-12 is TWELVE SPRINGS in a package.

I am ordering mine this week. The seat pressure is 60 lbs vs. the stock valve springs of 32lbs ( correct me if I am wrong guys).

This in turn keeps the valve from floating, or when the motor ( as IJ noted ) is accelerating faster than the valve spring can keep up...the valve "floats".

Not a good thing....though our motors are NON-interference, so even if the timing belt breaks or you float some valves...the probablitiy of your valves slamming into the pistons is far less if not any.

All in all, the comp cams valve sprnigs are an insanely cheap upgrade for the money and can save you a pain! But more often than not will keep your motor from winding out those 100+K mile springs that you have in there.....

Remember, the older the spring, the less the seat pressure is....they SAG....

-Jonathan

 

[IJ.]

Colin: The stock retainers and locks are pretty storng parts and should be fine even with upgraded springs.

I changed mine out for lighter components so I can rev it harder than stock redline.

Jon: Good post!

 

[siman]

Thanks IJ. I took the day off from work to induldge in reading about building up heads and what to do and the what NOTS do to LOL.

I did not know until yesterday evening that Ferrera had a CHEAPER but just as good valve spring retainer kit for our motors. HPF ( horse power freaks) has it. They are Al/Mag ( aluminum and magnesium ) retainers and they also sell stronger locketts (sp?) as well!

Its about $212 for the Mag/Al retainers and another $110 for the lockets.....thats not THAT bad.

-Jonathan

 

[figgie]

i have looked into this indepth.

valve and retainer won't gain you much maybe a 1gram or 2 gram weigh reduction tops which in the scheme of things is NOT that much. If there was a way to reduce the VALVE weight itself, then saving another gram or two WOULD be beneficial, but on stock or SS valves it is a waste of time. Perhaps if someone was running hollow sodium filled valves or some Titanium valves then I can see it.

 

[siman]

Figgie, we see your point! If we were lightweight N/A motors.....yes we would go that route, but if I may quote IJ again.....all we have to do is turn up the boost!

.....well hoping your motor can handle that extra boost

-Jonathan

 

[figgie]

nope,

even under boosted application the retainer and lockets will not do anything weight wise.

IJ is partly right but one thing he forgot and that I will address

when you run a compression test on the motor what are the readings?

140 psi.. triple the pressure on the bottom of the valve that is helping keep the pressure inside the cylinder vs. what. 40 psi tops on the fuel injector side? And this is without adding gasoline to the equation

140 psi > 40 psi (and i have yet to see a 7m handle that but for the sake of this argument lets believe it can). Valve will stay closed Only time this will actually not happen is when the valve is floating thanks to crappy springs then all that gas will backtrack out the intake and when it lights.. you have a top fuel dragster type explosion

 

[Clifton]

Manifold pressure and rev are what work against the spring. Stronger springs are not needed for more power in general. There are alot of people over 500rwhp with stock springs.The spring doesn't know how much power the engine is making. To say it will need to be spun higher too do it is completely different.

 

[IJ.]

Figgie: I went for the Shimless buckets and Ti retainers as it all adds up

I'm not saying you have to do it this way for high RPM but it makes life on all of the components a little easier if you can pull the weight out.

Boost will act on the backside of the Intake valve reducing the seat pressure until the Valve begins to open.

 

[siman]

Figgie: I went for the Shimless buckets and Ti retainers as it all adds up

I'm not saying you have to do it this way for high RPM but it makes life on all of the components a little easier if you can pull the weight out.

Boost will act on the backside of the Intake valve reducing the seat pressure until the Valve begins to open.

Exactly IJ!
Not saying ANYONE is wrong...but more so elaborating on the subject since this is not talked about alot ( not near as much as BHG or spun bearingswned: )

I would think ( as I stated earlier) and older "stock" spring will sag somewhat and lose its tension! If not the tension ( lb's ) of the cam pushing DOWN on the spring...but the RECOIL of the spring to close the valve in TIME.

The more hp you put on the motor, the more stress period. You might not rev as fast....

You cannot stray from the fact that the motor constantly is working AGAINST friction ( tires ). The harder you push the motor....the more stress..

The valve springs are not a BIG stressee, but can help the motor be more accurate in terms of making sure the valves close on time....and the more recoil pressure there is, the better your luck that the valves will SEAT faster and tighter in the valve bowl.



-Jonathan Mann

 

[siman]

Figgie: I went for the Shimless buckets and Ti retainers as it all adds up

I'm not saying you have to do it this way for high RPM but it makes life on all of the components a little easier if you can pull the weight out.

Boost will act on the backside of the Intake valve reducing the seat pressure until the Valve begins to open.

Yeah! I have all the retainers and locketts in one zip lock bag.....its about a pound!

and the valves are really heavy!! Stiffer valves springs will recoil the valves quicker though....the more tension the more weight the valve springs can handle....and the more power they can handle!

I think thats right?:icon_conf :biglaugh:

 

[lowbudgettarga]

i've got those comp valve springs and ferrea valves in my new engine, I can't say I notice a difference from them specifically, but they sure do make me feel good.