|
|
|
|
| Author |
|
|
Dog-faced pony soldier
|
Valve Float
I was reading about a post the other day about someone that redlined their tach and was afraid they might have "floated" the valves. What does this mean exactly? I'm unfamiliar with the term. Thanks!
__________________
A car, a 911, a motorbike and a few surfboards Black Cars Matter |
||
03-12-2004, 04:23 PM
|
|
|
Registered
Join Date: Dec 2001
Location: Cordova, TN
Posts: 1,222
|
The cam is turning so fast that the valve springs are not allowed to fully close the valves.
__________________
Roger Hall 81 924 N/A Some people are like Slinkies. Not really good for anything, but you still can't help but smile when you see one tumble down the stairs. |
||
|
03-12-2004, 05:00 PM
|
|
|
meister member
|
If the springs don't close the valves don't worry the pistons will!
__________________
1983 944 guards red with 16" Fuchs, Host of Wisconsin area timing/ balance shaft belt tensioning party 1987 944S Purchased from Legion. Corvette LT-1 V-8 conversion with Mega Squirt II Check on progress ---> www.porschehybrids.com/gallery/speedracing944 Favorite Road = www.tailofthedragon.com 318 turns in 11 miles (11 min 20 sec best run) |
||
|
03-12-2004, 06:33 PM
|
|
|
Dog-faced pony soldier
|
Thanks, makes sense. . . what would be the best prevention for that (besides running the engine at a lower rpm) - stronger return springs?
__________________
A car, a 911, a motorbike and a few surfboards Black Cars Matter |
||
|
03-12-2004, 07:01 PM
|
|
|
Registered
Join Date: Nov 2003
Location: Calgary, AB
Posts: 1,883
|
Both stronger return springs, and solid lifters.
Not a good upgrade for the average racer. The heads and manifolds don't flow well enough to warrant revving past 7000, which is where the valves will start floating. You would see more power by upshifting than letting it rev up.
__________________
2010 Hyundai Elantra Touring, GLS 5 speed, Indigo Blue Metallic. 2.0L of Korean fury! Buy my parts! |
||
|
03-12-2004, 07:57 PM
|
|
|
Registered
Join Date: Dec 2001
Location: Cordova, TN
Posts: 1,222
|
Typically valve float will not cause you to bend a valve. It can happen but that usually requires more than just redlining the engine. If you reach the RPM's necessary to blow the motor it probably wont matter wich parts exploded.
Alot of people will upgrade springs when rebuilding the head or installing a cam. The power band on your car is below 7000 RPS's though. So the best thing to do is to shift inside the power band.
__________________
Roger Hall 81 924 N/A Some people are like Slinkies. Not really good for anything, but you still can't help but smile when you see one tumble down the stairs. Last edited by Roger Hall; 03-12-2004 at 08:49 PM.. |
||
|
03-12-2004, 08:39 PM
|
|
|
|
Registered
Join Date: Jul 2001
Location: Edmonton, Alberta, Canada
Posts: 4,530
|
The only problem with stronger springs is that the stock hydraulic lifter were not designed for them so then you can have another problem which would cause the lifter to collapse......
Now you see why porsche left the red-line where it is.
__________________
Alex - PCA Polar Region - Boxster Muncher 86' 944 Turbo - Megasquirt - 326 rwhp/340lbft @ 18 psi SOLD www.edmontonhomelife.com www.edmontonrealestate.ws |
||
|
03-12-2004, 09:59 PM
|
|
|
Custom User Title
Join Date: Oct 2002
Location: Miami
Posts: 4,294
|
oops.
|
||
|
03-12-2004, 10:19 PM
|
|
|
least common denominator
Join Date: Aug 2001
Location: San Pedro,CA
Posts: 22,506
|
Quote:
Shift in the power band? Now where is the fun in that!
__________________
Gary Fisher 29er 2019 Kia Stinger 2.0t gone  1995 Miata Sold 1984 944 Sold I am not lost for I know where I am, however where I am is lost. - Winnie the poo. |
||
|
03-13-2004, 08:19 AM
|
|
|
Burn the fire.
|
Just keep it under 7 grand and you can have all the fun in the world.
__________________
[x] Working | [_] Broken: 2017 Victory Octane [x] Working | [_] Broken: 2005 Ram 1500 SLT w/5.7L Hemi "Drive it like you stole it." |
||
|
03-13-2004, 10:44 AM
|
|
|
Registered
Join Date: Jul 2003
Location: Cincinnati, OH
Posts: 1,025
|
hehe rx7 doesnt have valve float....
__________________
Special Edition 924S 1988 <- SOLD! Asking if you should replace that timing belt is like asking if you should re-use a condom that may have in hole in it with a hooker. |
||
|
03-13-2004, 12:37 PM
|
|
|
least common denominator
Join Date: Aug 2001
Location: San Pedro,CA
Posts: 22,506
|
Re: Valve Float
Quote:
Sorry couldn't resist.
__________________
Gary Fisher 29er 2019 Kia Stinger 2.0t gone 1995 Miata Sold 1984 944 Sold I am not lost for I know where I am, however where I am is lost. - Winnie the poo. |
||
|
03-13-2004, 03:21 PM
|
|
|
2017 Victory Octane
2005 Dodge Ram 1500 SLT
