how much boost can stock valvesprings hold

[TBurow]

how much boost can they hold before they begin to float or blow open?

 

["Mad Max"]

Not positive, but I think 50 psi is the magic number. After that o-rings and studs are also a good idea. Heavier exhaust valve springs (60 lb) are also recommended for installing exhaust brakes.

- M2

 

[CSchafer]

I don't believe you have to change them for running high boost just high rpm. I know 45 doesnt blow em open

 

[tkerrigan]

If anything high boost should keep the valves closed tighter.

 

[rlyons]

Boost will not affect the valve springs much because the open valves will allow for relief of pressure. You would have to have a lot of boost to blow open a valve.

 

[OKish]

i think he is talking about the intake side valves blowing open, like during an exhaust stroke.

 

[cerberusiam]

Boost will not affect the valve springs much because the open valves will allow for relief of pressure. You would have to have a lot of boost to blow open a valve.

You would be surprised at how easy it is to have both exhaust and intake hanging at high boost and/or rpm with stock springs. The 5. 9 is an inteference engine. Valves open at the wrong time and they do a little dance on the tops of the pistons.



I always figured when one starts hitting 50 psi boost and or 3200 rpm's on the 12V's it was time for updated springs.



The CR engines are runnign into the same problem at about 50 psi and 3500 rpm's though a lot will depend on how well flowing the exhaust system is.



If you think 12 is bad how about 24 valves tap dancing on the pistons? :-laf

 

[TWorline]

Years ago I had a 71 Challenger with a 318, the lifters would float at 5800. When we pulled the heads off after I dropped a built 360 in it, there were "eyebrows" on every piston. Never did bend a valve though.

 

[TBurow]

it was the intake valves i was worried about, i have the 3200 spring and am pretty close to 50 psi and dont want 6 new holes in the piston or a head full of crushed valves. maybe i should just turn it down a bit, nah, its too much fun driving it sideways when it takes off. time for some springs.

 

[dpuckett]

That or just do like I do, dont use all you got. 2 mo later, and I STILL have yet to floor it.



Daniel

 

[TWorline]

That or just do like I do, dont use all you got. 2 mo later, and I STILL have yet to floor it.



Daniel

You are a disciplined man Daniel!

 

[dpuckett]

Disciplined?

No, I am just too broke at this time to replace what would break if I used what I have available. :-laf



DP

 

[TWorline]

Been there done that! Actualy I'm probably still there

 

[PToombs]

I'm thinking like Daniel lately. I know my truck will keep pulling, I just back off at 3500. I don't want to see MY valves stuck in the pistons! I never did a no load test to see what it would turn, for the same reason. The next mod I do is all the valve springs!