Valve float is fun...
07-11-2003, 12:15 PM
#1
Registered User
Thread Starter
Join Date: Nov 2000
Location: Grandville/ Grand Rapids, Michigan
Posts: 1,003
Valve float is fun...
Yeah, My car experiences valve float at about 5600 rpm or so... The nice part about that is that the Stealth Ram manifold I have installed wants to rev to about 6500 rpm. Simple math tells you that when the powerband starts at 4500 and you have to shift out at 5500... you aren't gonna pull off too many great track times.
Ohh, and I never had my heads machined for bigger spring seats. So... looks like I'll be runnin 13's again this year.
Ohh, and I never had my heads machined for bigger spring seats. So... looks like I'll be runnin 13's again this year.
07-11-2003, 12:20 PM
#2
Registered User
Join Date: Oct 1999
Location: Battle Creek, MI
Posts: 3,532
will a hydra rev kit work in your situation? What about double or triple dampened coils? Is there enough seat space for them? Seems like you could find a spring with a higher seat pressure and same base diameter
07-11-2003, 12:59 PM
#3
Registered User
Thread Starter
Join Date: Nov 2000
Location: Grandville/ Grand Rapids, Michigan
Posts: 1,003
Mike, For some stupid reason GM made the spring seat 1.250"..... 
There are NO springs that fit in that seat except the Comp Cams Conical ones which are a single spring.
About the Hydra Rev kit... I don't know if that will help. I'm gonna have to call on that. Maybe Q knows.
There are NO springs that fit in that seat except the Comp Cams Conical ones which are a single spring. About the Hydra Rev kit... I don't know if that will help. I'm gonna have to call on that. Maybe Q knows.
07-11-2003, 01:17 PM
#4
Registered User
Join Date: Sep 2002
Location: Kalamazoo, MI
Posts: 472
I don't think a rev kit would help. 
When the valves float, they bounce off their seats when they close. The only way to fix that is with more seat pressure.
Brad, are you sure they're only 1.250" and not a teeny bit bigger? K-Motion makes a couple of springs that might help you out:
K-700: 1.265" single silicon spring, 115# seat, 350# open, $42.99
K-750: 1.265" single H-11 spring, 130# seat, 380# open, $129.99
Click here.
When the valves float, they bounce off their seats when they close. The only way to fix that is with more seat pressure.Brad, are you sure they're only 1.250" and not a teeny bit bigger? K-Motion makes a couple of springs that might help you out:
K-700: 1.265" single silicon spring, 115# seat, 350# open, $42.99
K-750: 1.265" single H-11 spring, 130# seat, 380# open, $129.99
Click here.
Last edited by TheNovaMan; 07-11-2003 at 01:19 PM.
07-11-2003, 01:25 PM
#5
Registered User
Thread Starter
Join Date: Nov 2000
Location: Grandville/ Grand Rapids, Michigan
Posts: 1,003
Pete, Check this out.
CLICK ME
Says there that the 982 Kit has an installed height of 1.750 and that means a 100# seat pressure. And 299# open (max lift.)
I was talking to a guy yesterday and he said that 138# may be on the high side... (referring to the springs we were looking at.)
I'll look into it.
CLICK ME
Says there that the 982 Kit has an installed height of 1.750 and that means a 100# seat pressure. And 299# open (max lift.)
I was talking to a guy yesterday and he said that 138# may be on the high side... (referring to the springs we were looking at.)
I'll look into it.
07-11-2003, 01:42 PM
#6
Registered User
Join Date: Sep 2002
Location: Kalamazoo, MI
Posts: 472
I agree that 130# is alot for a hydraulic cam, but I think 100 is a bit low if you're going to the trouble of upgrading anyway. The K700 silicon springs have a seat pressure of 115#, which sounds just about right to me... and they're pretty economical too. 
(BTW, I have the same problem. It sucks! 
)
(BTW, I have the same problem. It sucks! )
07-11-2003, 05:57 PM
#11
Registered User
Thread Starter
Join Date: Nov 2000
Location: Grandville/ Grand Rapids, Michigan
Posts: 1,003
Yeah, its horrible. Dude, If I had the $$$ and time right now I would be doing the springs... Can you say winding out to 6500 RPM? 
Maybe not that high but I need to be able to spin to 6000 RPM. If I shift at 6000 I will drop to roughly 3-400 rpm before the **** hits the fan and she really starts haulin. Powerband the whole way down the track would be sweet! Hell 6200 RPM would rock.
Maybe not that high but I need to be able to spin to 6000 RPM. If I shift at 6000 I will drop to roughly 3-400 rpm before the **** hits the fan and she really starts haulin. Powerband the whole way down the track would be sweet! Hell 6200 RPM would rock.
07-12-2003, 12:08 AM
#12
Registered User
Join Date: Jun 2001
Location: waterford, MI - USA
Posts: 3,738
solid cam/economical typical springs, 7500 rpm and no float. ofcourse, my eng. dont make power that high, so I dont shift that high now, more like 6500 rpm.
why doesnt everyone use solid cams for there hot rods?
good luck finding springs to help your problem. my big block did that back in the day, that sucked. till I put a solid cam in it.
why doesnt everyone use solid cams for there hot rods?
good luck finding springs to help your problem. my big block did that back in the day, that sucked. till I put a solid cam in it.
07-13-2003, 12:46 AM
#14
Registered User
Join Date: Feb 2003
Posts: 9
I saw your post over on TGO also.
100# at 1.75 seat and 281# at 1.25 (.500 lift) - which is a 362# spring rate per inch - should be able to control the valves better than what you're experiencing,,, but once you start "floating" the valves, the springs get weaker and weaker after each episode. Do you know the brand springs? Those specs are close to the 981 comp that's rated 110# at 1.700 seat, setting that spring to 1.750 seat drops the pressure to 82#.
As a stop gap until you can replace the springs, back off the adjustment on the lifters to 1/8 of a turn. Doing this only allows the lifter to pump up about .008" if it unloads,,, compared to .030" at 1/2 turn. You should see a difference,, unless you've already totally killed the springs.
As far as being concerned about 130# seat pressure,,, don't. The same flat tappet hydraulic lifter is used for the SBC and the BBC and most BBC hydraulic springs run in the 125# - 130# seat range. What you have to watch for is the spring rate - unless you have a REAL aggressive lobe profile, you want a spring rate that will give you around 300# (no more than 320#) at max cam lift.
I've set a number of heads to the specs that I'm running - 110# at seat and 310# at max lift (Comp 983s) and I shift at 6400. I've taken the car as high as 6600 rpm on the dyno (once to 7000 at the track) and I'm not experiencing any problems (and neither has anyone else).
As far as the K-700 K-motions, they were the springs that gave the G1 TFS heads such a bad rep back around 1994 and we sold 5 sets from my old speed shop in 1998 --- after the K-Motion rep assured me the newer springs were giving them no problems --- 4 out of the 5 set we sold had inner dampner breakage and 2 of those sets had spring breakage. I tried to get them replaced and they claimed installation / application error. I sold the guy the springs, I sold the guy the cam, and I checked the spring height when he brought the heads in and threw them on the counter demanding a refund on the springs and the cost of the gaskets - there was NO application error on this - or the others. I later found out through a contact at TFS that K-Motion never admitted to there being a problem with K-700 back in 1994 even after about 1/3 of the heads TFS sold with those springs experienced a problem,, sorry about the rant,, but they suck as a product and as a company (at least from 1994 - 1998). Novaman, I hope if you're running them they've REALLY made some changes since 98.
100# at 1.75 seat and 281# at 1.25 (.500 lift) - which is a 362# spring rate per inch - should be able to control the valves better than what you're experiencing,,, but once you start "floating" the valves, the springs get weaker and weaker after each episode. Do you know the brand springs? Those specs are close to the 981 comp that's rated 110# at 1.700 seat, setting that spring to 1.750 seat drops the pressure to 82#.
As a stop gap until you can replace the springs, back off the adjustment on the lifters to 1/8 of a turn. Doing this only allows the lifter to pump up about .008" if it unloads,,, compared to .030" at 1/2 turn. You should see a difference,, unless you've already totally killed the springs.
As far as being concerned about 130# seat pressure,,, don't. The same flat tappet hydraulic lifter is used for the SBC and the BBC and most BBC hydraulic springs run in the 125# - 130# seat range. What you have to watch for is the spring rate - unless you have a REAL aggressive lobe profile, you want a spring rate that will give you around 300# (no more than 320#) at max cam lift.
I've set a number of heads to the specs that I'm running - 110# at seat and 310# at max lift (Comp 983s) and I shift at 6400. I've taken the car as high as 6600 rpm on the dyno (once to 7000 at the track) and I'm not experiencing any problems (and neither has anyone else).
As far as the K-700 K-motions, they were the springs that gave the G1 TFS heads such a bad rep back around 1994 and we sold 5 sets from my old speed shop in 1998 --- after the K-Motion rep assured me the newer springs were giving them no problems --- 4 out of the 5 set we sold had inner dampner breakage and 2 of those sets had spring breakage. I tried to get them replaced and they claimed installation / application error. I sold the guy the springs, I sold the guy the cam, and I checked the spring height when he brought the heads in and threw them on the counter demanding a refund on the springs and the cost of the gaskets - there was NO application error on this - or the others. I later found out through a contact at TFS that K-Motion never admitted to there being a problem with K-700 back in 1994 even after about 1/3 of the heads TFS sold with those springs experienced a problem,, sorry about the rant,, but they suck as a product and as a company (at least from 1994 - 1998). Novaman, I hope if you're running them they've REALLY made some changes since 98.
Last edited by BadRocZ; 07-13-2003 at 12:51 AM.
07-13-2003, 01:40 AM
#15
Registered User
Join Date: Sep 2002
Location: Kalamazoo, MI
Posts: 472
I'm not running them as of now, but I'm going to buy a set of K-700s from a friend at the CZ28.com Nationals. I realize they have had problems, but they must be good overall if Warren Johnson (and so many other Pro teams) uses them. I'll definitely give them a call before I use them to make sure they are "correct" for my application. Thanks for the heads-up.