L98 valve float
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: L98 valve float (GRX)
On a high mileage L98 with stock valve springs ( IE: they are worn out by now )...valve float does start at around 4000 RPM.
Of course, the others are right too...the intake/cam combo is designed for low rpm power, so it's going to roll off at about 4500-5000 RPM anyway. It's more limited by camshaft profile than by intake runner design though.
Of course, the others are right too...the intake/cam combo is designed for low rpm power, so it's going to roll off at about 4500-5000 RPM anyway. It's more limited by camshaft profile than by intake runner design though.
Le Mans Master
Joined: Jul 2001
Posts: 5,297
Likes: 0
From: Stamford VT
Re: L98 valve float (BBA)
I've never seen a V8 with springs so worn that it starts to float at 4,000 rpm. My 135k mile GTA doesn't float at 5,500 rpm. Scorp, you ever get float with your 160k mile motor?
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: L98 valve float (Jim85IROC)
What ever you say.
Here is how to tell...pull a valve cover, lean on the rocker by hand...if it pushes the valve open...the valve springs are shot.
Every L98 I ever saw, that had close to or over 100 K miles had worn out valve springs.
And yes...valve float is something 90% of the drivers can not even recognize.
Here is how to tell...pull a valve cover, lean on the rocker by hand...if it pushes the valve open...the valve springs are shot.
Every L98 I ever saw, that had close to or over 100 K miles had worn out valve springs.
And yes...valve float is something 90% of the drivers can not even recognize.
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Le Mans Master
Joined: May 2002
Posts: 5,446
Likes: 1
From: 10.70 @ 124mph, Stock Bottom End @ 3620lbs, ECS Racing Team Member. The 1st NMCA LSX Index Rumble World Champion. 2011,12,13 Champion
Re: L98 valve float (GRX)
I have 138,332 miles on my 89 and I don't have valve float. My MPH on the track is greater then my ET. I have more MPH then I should, Not by much but better, I have the original valve springs in my car. Everybody is correct with what they said. I feel that it also depends on how the car is driven. If you drive the car hard your valve springs will not last long. Do you let the engine tempature come up before driving the car? Why do I ask this you ask? I ask this because, If you drive a cold engine with cold valve springs you will shorten there life. A cold valve spring is sensitive and weak when cold. Just as a race car, You start the enginge and hold it at 1,500 to 2,000 till the engine has heat (About 160) on the temp.
