355 LE Dyno tune this Friday...Guess my numbers
03-30-2008, 09:51 AM
#76
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Location: Lantana, TX
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Just because it's me, I would be too curious to just slap another set of springs in there. I would want to go back and install them at 1.75 and see if it really helped out the situation both in terms of the small pressure increase and also concerning clearance to solid state. There has been much debate over this for a while. Kinda like the whole single plane conversion. When someone finally did it you could see that the gains weren't there on a street motor and all it did was help distribution.
03-30-2008, 10:07 AM
#77
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Join Date: May 1999
Location: Prestonsburg, Ky
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Just because it's me, I would be too curious to just slap another set of springs in there. I would want to go back and install them at 1.75 and see if it really helped out the situation both in terms of the small pressure increase and also concerning clearance to solid state. There has been much debate over this for a while. Kinda like the whole single plane conversion. When someone finally did it you could see that the gains weren't there on a street motor and all it did was help distribution.
03-30-2008, 10:20 AM
#78
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Location: Lantana, TX
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Well that's not good, are you going to wait and see what Bill's car does with the new springs before you do it to yours or have you already got stuff ready to go?
03-30-2008, 10:40 AM
#79
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Join Date: May 1999
Location: Prestonsburg, Ky
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I am waiting on my spring to come in, they should be here Monday or tuesday, then trying to get them installed, I hope to this week, but it depends on scheduling.....I wish I could do this, but I have no ideal what to do, because I am a dumbass when it comes to this stuff, but I'm learning everyday........
03-30-2008, 10:46 AM
#80
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Well clearly my valve springs install height are out of spec by ~.030" or so to the tall side. I hope that this is the smoking gun.
And again since all the valve train would get pulled I am in favor of throwing my brand new Comp 26921 dual springs w/ titanium retainers on at the correct height and throw the pressure issue out the window for good, they are 5/70 stronger than the beehives. Plus I would feel better having dual springs in case one ever broke. This would give the motor a fighting chance at surviving.
Regarding push rods I am using Comp Hi-tech 7.00" in size. According to the sharpie sweep test when I built the motor the PR size is correct. Rocker geometry is dead on so I know its not push rods. This bit me once in the past and wore my guide plates severly. I have been watching the guide plates on this motor from day one and they dont show the slightest blemish of any wear.
And again since all the valve train would get pulled I am in favor of throwing my brand new Comp 26921 dual springs w/ titanium retainers on at the correct height and throw the pressure issue out the window for good, they are 5/70 stronger than the beehives. Plus I would feel better having dual springs in case one ever broke. This would give the motor a fighting chance at surviving.
Regarding push rods I am using Comp Hi-tech 7.00" in size. According to the sharpie sweep test when I built the motor the PR size is correct. Rocker geometry is dead on so I know its not push rods. This bit me once in the past and wore my guide plates severly. I have been watching the guide plates on this motor from day one and they dont show the slightest blemish of any wear.
David Vizard claims beehives need as much as 25% less pressure to control the same valvetrain so you are not taking as big a step up as you think you are, those titanium retainers, I bet are just as heavy as the tiny beehive steel ones too so I am doubtful of gain there.
03-30-2008, 11:04 AM
#81
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Location: Lantana, TX
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Is that 25% seat pressure? I've never understood how that works, you need a certain pressure seated and open to control a valve. I could understand less seated pressure because of the design of the spring, but that's it. Is there a link or something to an article because I would like to read it to understand more.
03-30-2008, 11:07 AM
#82
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Join Date: Oct 2001
Location: SoCal
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The guys I listen to say that installed height isn't just about load even though that is very important, but it is about how close the spring is to solid at maximum valve lift. If it is too far from solid the spring surge may not let the spring control the valve. If the 1.750 installed height gives .050 from solid height at full lift, installing them at 1.180 would give .100 from solid. This would probably have a dramatic effect on surge and valvetrain contol. The guys I get to listen to talk about distance from solid height at max valve lift in numbers closer to .050 than to .100. They build some pretty stout engines so I tend to believe what they say.
I saw some slow motion video that showed how small clearances to solid height really helped control the valves. It all started to make sense to me then. I guess if the guy who designed the cam said installed height was very important I would follow his advice. When I have done that I have not had problems. Maybe I am just lucky.
Joe Urban
I saw some slow motion video that showed how small clearances to solid height really helped control the valves. It all started to make sense to me then. I guess if the guy who designed the cam said installed height was very important I would follow his advice. When I have done that I have not had problems. Maybe I am just lucky.
Joe Urban
03-30-2008, 11:39 AM
#83
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David Vizard claims beehives need as much as 25% less pressure to control the same valvetrain so you are not taking as big a step up as you think you are, those titanium retainers, I bet are just as heavy as the tiny beehive steel ones too so I am doubtful of gain there.
This whole thing is just turning my brain into mush. What ever is happening it is like a switch that gets thrown to turn the power off at exactly 6000 RPM. Many people run beehives on faster cams with success and claim no valve float. It just seems to me that 6000 RPM is just too low for a 130# / 320# spring to not be able to control the valves.
I am going to get some run some Datamaster logs this evening to see if the drop off appears there. If it does I will have a bench line that I can compare changes too. I am going to set my lifter preload at 1/8" past zero lash first since that is rather quick and easy. If no improvement then install the 921's.
I imagine that Doug will get his done and dynoed before me.
Who here thinks my current (new GM) lifter preload at 1/4" PZL is the problem?
03-30-2008, 11:47 AM
#84
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Join Date: Mar 2002
Location: Ocala, Florida
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I am not ready to switch them out quite yet. I need a set of new keepers first. Probobly would not toch till mid week if at all this week.
I don't really care about the titanium retainers and gains. The springs are certainly much stronger than the 1218 beehives. Thats my concern now.
This whole thing is just turning my brain into mush. What ever is happening it is like a switch that gets thrown to turn the power off at exactly 6000 RPM. Many people run beehives on faster cams with success and claim no valve float. It just seems to me that 6000 RPM is just too low for a 130# / 320# spring to not be able to control the valves.
I am going to get some run some Datamaster logs this evening to see if the drop off appears there. If it does I will have a bench line that I can compare changes too. I am going to set my lifter preload at 1/8" past zero lash first since that is rather quick and easy. If no improvement then install the 921's.
I imagine that Doug will get his done and dynoed before me.
Who here thinks my current (new GM) lifter preload at 1/4" PZL is the problem?
I don't really care about the titanium retainers and gains. The springs are certainly much stronger than the 1218 beehives. Thats my concern now.
This whole thing is just turning my brain into mush. What ever is happening it is like a switch that gets thrown to turn the power off at exactly 6000 RPM. Many people run beehives on faster cams with success and claim no valve float. It just seems to me that 6000 RPM is just too low for a 130# / 320# spring to not be able to control the valves.
I am going to get some run some Datamaster logs this evening to see if the drop off appears there. If it does I will have a bench line that I can compare changes too. I am going to set my lifter preload at 1/8" past zero lash first since that is rather quick and easy. If no improvement then install the 921's.
I imagine that Doug will get his done and dynoed before me.
Who here thinks my current (new GM) lifter preload at 1/4" PZL is the problem?
Cam size has nothing to do with valve float, how aggressive the lobes are is the main cause. The lobes on your cam make the XFI stuff look like nothing.
03-30-2008, 12:48 PM
#85
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03-30-2008, 12:50 PM
#86
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I am not ready to switch them out quite yet. I need a set of new keepers first. Probobly would not toch till mid week if at all this week.
I don't really care about the titanium retainers and gains. The springs are certainly much stronger than the 1218 beehives. Thats my concern now.
This whole thing is just turning my brain into mush. What ever is happening it is like a switch that gets thrown to turn the power off at exactly 6000 RPM. Many people run beehives on faster cams with success and claim no valve float. It just seems to me that 6000 RPM is just too low for a 130# / 320# spring to not be able to control the valves.
I am going to get some run some Datamaster logs this evening to see if the drop off appears there. If it does I will have a bench line that I can compare changes too. I am going to set my lifter preload at 1/8" past zero lash first since that is rather quick and easy. If no improvement then install the 921's.
I imagine that Doug will get his done and dynoed before me.
Who here thinks my current (new GM) lifter preload at 1/4" PZL is the problem?
I don't really care about the titanium retainers and gains. The springs are certainly much stronger than the 1218 beehives. Thats my concern now.
This whole thing is just turning my brain into mush. What ever is happening it is like a switch that gets thrown to turn the power off at exactly 6000 RPM. Many people run beehives on faster cams with success and claim no valve float. It just seems to me that 6000 RPM is just too low for a 130# / 320# spring to not be able to control the valves.
I am going to get some run some Datamaster logs this evening to see if the drop off appears there. If it does I will have a bench line that I can compare changes too. I am going to set my lifter preload at 1/8" past zero lash first since that is rather quick and easy. If no improvement then install the 921's.
I imagine that Doug will get his done and dynoed before me.
Who here thinks my current (new GM) lifter preload at 1/4" PZL is the problem?
The spring has to control total valvetrain mass, the spring and retainer themselves being part of that mass and the part of the beehive that moves the most and the retainer are vastly lighter than older style stuff meaning much less mass has to be controlled so less pressure is needed.
These problems have played out repeatedly and everyone just refuses to admit the causes.
03-30-2008, 01:22 PM
#87
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The spring has to control total valvetrain mass, the spring and retainer themselves being part of that mass and the part of the beehive that moves the most and the retainer are vastly lighter than older style stuff meaning much less mass has to be controlled so less pressure is needed.
These problems have played out repeatedly and everyone just refuses to admit the causes.
These problems have played out repeatedly and everyone just refuses to admit the causes.
what would suggest we do?
03-30-2008, 01:23 PM
#88
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Join Date: Jun 2003
Location: Saginaw, Michigan
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What size rocker stud are you using?
Proper preload for stock 3/8" studs is 1/2 turn PZL and for 7/16" studs is 3/8 turn PZL. I calculated this a while back and know it to be correct for stock GM lifters. The difference is due to the thread pitch differnece between 3/8 and 7/16" studs. You propably already knew that, but thought I would throw it out there.
I have 7/16" studs with the 1.6RR Pro Mags, and they are nearly silent with no problems now after around 20k miles,
If it were me, I would shim up your springs to get the correct seat pressure, and set your lifter pleload as I describe and give that a whirl.
Dan
Proper preload for stock 3/8" studs is 1/2 turn PZL and for 7/16" studs is 3/8 turn PZL. I calculated this a while back and know it to be correct for stock GM lifters. The difference is due to the thread pitch differnece between 3/8 and 7/16" studs. You propably already knew that, but thought I would throw it out there.
I have 7/16" studs with the 1.6RR Pro Mags, and they are nearly silent with no problems now after around 20k miles,
If it were me, I would shim up your springs to get the correct seat pressure, and set your lifter pleload as I describe and give that a whirl.
Dan
Last edited by stereomandan; 03-30-2008 at 01:25 PM.
03-30-2008, 01:42 PM
#89
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