Valve springs

[Ziegelsteinfaust]

As I slog through my Nova build. I am trying to figure out where I want to take things.

My new engine is a 1996 4.3 L99 or baby LT1, and I threw in a Corvette cam to liven it up a bit.

I have the factory Corvette valve springs. Which have a tendency to float, but I also have some spring good to 560 lift. When the can has 460 lift.

Is there such a thing as functionally to much valve spring, and there a rough starting point.

[RustyPile]

Originally Posted by Ziegelsteinfaust

As I slog through my Nova build. I am trying to figure out where I want to take things.

My new engine is a 1996 4.3 L99 or baby LT1, and I threw in a Corvette cam to liven it up a bit.

I have the factory Corvette valve springs. Which have a tendency to float, but I also have some spring good to 560 lift. When the can has 460 lift.

Is there such a thing as functionally to much valve spring, and there a rough starting point.

Gross lift and RPM operating range are the prime considerations when selecting valve springs.. Any valve will float if pushed beyond the spring's RPM operating range. At what RPM do those Corvette springs "tend to float"?? You can add shims to those .560 springs and raise their RPM operating range.. This also increases the seat pressure and lifter load on the cam, which can increase cam wear and or lobe failure. Pay close attention to spring installed height specs when setting everything up..

[AussieinNC]

The attached link will give you heaps of info on an L99 Little motor...

https://www.onallcylinders.com/2021/...8-gets-torque/

[Ziegelsteinfaust]

Originally Posted by RustyPile

Gross lift and RPM operating range are the prime considerations when selecting valve springs.. Any valve will float if pushed beyond the spring's RPM operating range. At what RPM do those Corvette springs "tend to float"?? You can add shims to those .560 springs and raise their RPM operating range.. This also increases the seat pressure and lifter load on the cam, which can increase cam wear and or lobe failure. Pay close attention to spring installed height specs when setting everything up..

Seems like 5000-5500 on the early side if you have a issue. 6000 seems more like normal or better new springs

[RustyPile]

Originally Posted by AussieinNC

The attached link will give you heaps of info on an L99 Little motor...

https://www.onallcylinders.com/2021/...8-gets-torque/

Yep.... And nowhere during those dyno pulls of 6000 RPM and above, do they say a word about valve float...

[Ziegelsteinfaust]

Originally Posted by RustyPile

Yep.... And nowhere during those dyno pulls of 6000 RPM and above, do they say a word about valve float...

You should watch the LT1 episodes.

Also as stated I switched cams. Which can go start going into valve float with factory springs around 5500 if they want too.

[RustyPile]

Originally Posted by Ziegelsteinfaust

You should watch the LT1 episodes.

Also as stated I switched cams. Which can go start going into valve float with factory springs around 5500 if they want too.

I'll be the first to admit I know very little about the latest iteration of the LT1, but back in my racing days, I used the 1st generation LT1 as the "foundation" for my race engines.. Zyglo'd rods, heads, everything.. Super Stock got turned to around 6500 - 6800.. The more potent Super Modified engines got turned to 8K plus.. On those, I used a more aggressive cam and triple spring aftermarket valve springs..

Maybe I just don't understand the goal of this project.. But this I do know.. The more an engine is modified in order to raise it's output, the less reliable it becomes.. Instead of building a 262 cu. in. peanut pusher of say 400 HP, that depends on high RPM to get around, why not build a 400 HP 383 (same physical size and approximate weight) that will make gobs of torque at a much lower RPM, and be much more reliable????

[Ziegelsteinfaust]

Originally Posted by RustyPile

I'll be the first to admit I know very little about the latest iteration of the LT1, but back in my racing days, I used the 1st generation LT1 as the "foundation" for my race engines.. Zyglo'd rods, heads, everything.. Super Stock got turned to around 6500 - 6800.. The more potent Super Modified engines got turned to 8K plus.. On those, I used a more aggressive cam and triple spring aftermarket valve springs..

Maybe I just don't understand the goal of this project.. But this I do know.. The more an engine is modified in order to raise it's output, the less reliable it becomes.. Instead of building a 262 cu. in. peanut pusher of say 400 HP, that depends on high RPM to get around, why not build a 400 HP 383 (same physical size and approximate weight) that will make gobs of torque at a much lower RPM, and be much more reliable????

The engine family I am playing with is the mid 90's gen2 LT1.

It is a DD engine, and I have a stash of LT1 parts already. So while it's apart I just added things I wanted that do not or will likely not have another home otherwise.

It should be good for close too 270hp crank max. Which is a nice fun amount of hp.

Combined with my 3.23 geared rear end, and eventual 2000 stall converter. It will meet all my need/wants for my DD.

The Corvette cam is actually very mild, and they have no issues running 250,000 miles or more. If properly maintained. The B-body cam is really mild barely above the status of the generic flat tappets before it.

The LT1 heads are where like the later LS the HP/tq come from. My 4.3 heads technically can support 425hp like the aluminum 350 LT1 heads, but I would have to spin around 7500 to get it. Where they can get there at 5000-5500 with a mild can swap. So adding a cam/spring combo I already own. Only will cost me if I add the springs other wise I will use then on my 350 I just built like they were bought for anyways.