More serious lifter problem: pump up or bleed down
12-15-2008, 07:06 PM
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More serious lifter problem: pump up or bleed down Alright fellas, I've searched and searched and I'm about to go crazy trying to setup the valvetrain on my heads/cam build. Specifically I can't figure out what preload my caddy racing lifters need. Before anyone says anything, I know people have had problems with these, but I'm already overbudget and can't afford Morels, that's why I'm trippin. I'm using milled PRC 2.5s with their dual springs, a VRX5 (comp xer 236/238) cam, and yella terras shimmed for good valve wipe (thx vettenuts). According to my comp pushrod checker, 7.31" puts me at zero lash (10.25 turns out). So I need 7.37" for .060" preload, which is what SDPC recommends... So far so good right? Well in my searching, I found a guy who says .060 is a typo, and it really should be double that. Says he gained ~20hp to prove it. But there was another guy who had great luck running just .040". Countless others are running .060-.100. See where I'm going with this??
Basically I'm at the point now where I'd like to know what the tendencies are of these lifters (pump up or bleed down) with PRC springs, German Castrol Syntec oil, and 7000rpm, and which way I should err on pushrod length to prevent said problem. I talked to a few vendors and didn't really get a straight answer.
I'm about to lose it. Thanks
Basically I'm at the point now where I'd like to know what the tendencies are of these lifters (pump up or bleed down) with PRC springs, German Castrol Syntec oil, and 7000rpm, and which way I should err on pushrod length to prevent said problem. I talked to a few vendors and didn't really get a straight answer.
I'm about to lose it. Thanks
12-15-2008, 07:58 PM
#3
Here's a bunch of information I've gathered concerning lifter preload and the LSx engine. Note I'm currently running stock LS7 replacement lifters with .084" preload and have no issues.
From Crane Cams:
LS1/LS6 Engines: Lifter Preload And Its Affect On Valve Spring Life!
Chevrolet's LS1/LS6 engine family has gained wide usage in most all 2000 to present GM light duty trucks, as well as the Corvettes and Camaro/Firebirds. Some aftermarket manufacturers are recommending setting the hydraulic valve lifter preload at .004" -.010" (hot) for maximum performance applications. Many tuners and enthusiasts are not paying attention to the (hot) requirement of this lifter preload specification. This little bit of negligence is wreaking havoc with all LS1/LS6 valve springs. Two problems exist; first, trying to set preload on a street driven LS1/LS6 with the engine hot is next to impossible. The engine will cool down before you can get the coil packs and the valve covers off. Second, these engines feature an aluminum block and heads; the trucks features an iron block with aluminum heads. The aluminum engine castings expand more than twice as fast as the steel valve train components. If a tuner or enthusiast sets the lifter preload at .004" -.010" with a cool engine there will actually be .002" -.008" of valve lash by the time the engine comes up to operating temperature. The hydraulic roller valvetrain has no clearance ramp to take up this lash and, as a result, the lash causes a hammering action to take place in the valvetrain. This has a devastating affect on spring life and strength. In addition, it creates a great deal of noise that causes the knock sensor to retard timing (unless the knock sensor is disabled), resulting in a loss of power and higher than normal engine temperatures.
Lifter preload settings of .004" -.010" (hot) have been recommended for years (by many aftermarket cam companies including Crane) for maximum effort applications with flat tappet hydraulic valvetrains, but extensive testing at Crane Cams R&D Department has proven conclusively that hydraulic roller lifter valvetrains operate best with .050" -.080" of lifter preload. These is no sacrifice of low-end power and the power holds on beyond the power peak much more noticeably. We have expressed this in previous newsletters and several magazine editors and independent tuners have corroborated our findings. It is our opinion that improper (inadequate) lifter preload is one of the major causes of valve spring failure (regardless of manufacturer and spring design) on LS1 engines (especially because of the significant thermal expansion properties of the aluminum engine castings).
From Katech:
1) The only way to properly check (and know where you are in the travel) is to use a special checking lifter or completely compress a stock lifter.
a) Checking lifter consists of a lifter that has been disassembled to install shims that lock the plunger at the top of travel in the lifter body. If using this method you would add length to the checking pushrod to put the final pushrods into the middle of travel of the plunger.
b) Using a stock lifter, you must make certain that you have pumped all the oil out of the lifter. To do this leave it at valve full open (highest spring load) for a while with an indicator on the pushrod side of the rocker. Watch to see when the indicator stops moving (when the plunger is fully compressed in the lifter body). Once you have compressed the lifter rotate the engine to close the valve, extend your checking pushrod to full length. Using this method you will subtract length from your checking pushrod to put the final pushrods into the middle of travel of the plunger.
2) Typical plunger travel on Gen 3/4 lifters is 0.150" - 0.200" depending on the manufacturer, year, etc. We recommend 0.075" -0.100" from the bottom of travel (using method 'b' described above) or 0.075 from the top of travel (using method 'a' described above). That will generally put you close to the middle of travel. While there are many different strategies for where to put the plunger, for street use we strongly suggest that near the middle of travel is the safest for durability.
3) The more precise method of checking is 'a' because you are not guessing that you got all the oil out.
From Vinci High Performance:
LS1 Lifter Preload - Some other manufacturers are recommending a very small amount of preload for the Hydraulic Roller Lifters (.010” or less). This might work on flat faced hydraulic lifters but will not work or help you in getting any more power or RPM out of a hydraulic roller. If anything, it will only hurt your performance and upper RPM capabilities. These small amounts of preload can cause an excessive amount of valvetrain instability and cause excessive amounts of wear and damage to your parts since you would actually be getting a lash setting when the aluminum block and heads reach operating temperature! The hydraulic roller lifter needs a larger amount of preload. On the LS1 engine we recommend .050” - .080” of preload, which actually helps in gaining power at the drop off point of the engine’s power range and increasing your RPM band past your engine’s normal operating range.
From an unknown member posting about the caddy lifters:
I mounted my magnetic base dial indicator and put it on the oil hole in the rocker arm and began to slowly back off of the bolt that holds the rocker down, watching the dial. When loosening the nut, I saw a sweep of .180" from bottomed out lifter to fully extended lifter. I confirmed that reading by repeating the procedure, only tightening the nut this time. Again, .180". I had heard that .060" was the norm for LS1 lifters; however, I also heard on hydraulic roller lifters to set preload in the middle, which in this case would be .090". I am currently using a pushrod that gives .060" preload with no issues, sewing machine noise is very faint. Hope this info helps out.
HTH,
From Crane Cams:
LS1/LS6 Engines: Lifter Preload And Its Affect On Valve Spring Life!
Chevrolet's LS1/LS6 engine family has gained wide usage in most all 2000 to present GM light duty trucks, as well as the Corvettes and Camaro/Firebirds. Some aftermarket manufacturers are recommending setting the hydraulic valve lifter preload at .004" -.010" (hot) for maximum performance applications. Many tuners and enthusiasts are not paying attention to the (hot) requirement of this lifter preload specification. This little bit of negligence is wreaking havoc with all LS1/LS6 valve springs. Two problems exist; first, trying to set preload on a street driven LS1/LS6 with the engine hot is next to impossible. The engine will cool down before you can get the coil packs and the valve covers off. Second, these engines feature an aluminum block and heads; the trucks features an iron block with aluminum heads. The aluminum engine castings expand more than twice as fast as the steel valve train components. If a tuner or enthusiast sets the lifter preload at .004" -.010" with a cool engine there will actually be .002" -.008" of valve lash by the time the engine comes up to operating temperature. The hydraulic roller valvetrain has no clearance ramp to take up this lash and, as a result, the lash causes a hammering action to take place in the valvetrain. This has a devastating affect on spring life and strength. In addition, it creates a great deal of noise that causes the knock sensor to retard timing (unless the knock sensor is disabled), resulting in a loss of power and higher than normal engine temperatures.
Lifter preload settings of .004" -.010" (hot) have been recommended for years (by many aftermarket cam companies including Crane) for maximum effort applications with flat tappet hydraulic valvetrains, but extensive testing at Crane Cams R&D Department has proven conclusively that hydraulic roller lifter valvetrains operate best with .050" -.080" of lifter preload. These is no sacrifice of low-end power and the power holds on beyond the power peak much more noticeably. We have expressed this in previous newsletters and several magazine editors and independent tuners have corroborated our findings. It is our opinion that improper (inadequate) lifter preload is one of the major causes of valve spring failure (regardless of manufacturer and spring design) on LS1 engines (especially because of the significant thermal expansion properties of the aluminum engine castings).
From Katech:
1) The only way to properly check (and know where you are in the travel) is to use a special checking lifter or completely compress a stock lifter.
a) Checking lifter consists of a lifter that has been disassembled to install shims that lock the plunger at the top of travel in the lifter body. If using this method you would add length to the checking pushrod to put the final pushrods into the middle of travel of the plunger.
b) Using a stock lifter, you must make certain that you have pumped all the oil out of the lifter. To do this leave it at valve full open (highest spring load) for a while with an indicator on the pushrod side of the rocker. Watch to see when the indicator stops moving (when the plunger is fully compressed in the lifter body). Once you have compressed the lifter rotate the engine to close the valve, extend your checking pushrod to full length. Using this method you will subtract length from your checking pushrod to put the final pushrods into the middle of travel of the plunger.
2) Typical plunger travel on Gen 3/4 lifters is 0.150" - 0.200" depending on the manufacturer, year, etc. We recommend 0.075" -0.100" from the bottom of travel (using method 'b' described above) or 0.075 from the top of travel (using method 'a' described above). That will generally put you close to the middle of travel. While there are many different strategies for where to put the plunger, for street use we strongly suggest that near the middle of travel is the safest for durability.
3) The more precise method of checking is 'a' because you are not guessing that you got all the oil out.
From Vinci High Performance:
LS1 Lifter Preload - Some other manufacturers are recommending a very small amount of preload for the Hydraulic Roller Lifters (.010” or less). This might work on flat faced hydraulic lifters but will not work or help you in getting any more power or RPM out of a hydraulic roller. If anything, it will only hurt your performance and upper RPM capabilities. These small amounts of preload can cause an excessive amount of valvetrain instability and cause excessive amounts of wear and damage to your parts since you would actually be getting a lash setting when the aluminum block and heads reach operating temperature! The hydraulic roller lifter needs a larger amount of preload. On the LS1 engine we recommend .050” - .080” of preload, which actually helps in gaining power at the drop off point of the engine’s power range and increasing your RPM band past your engine’s normal operating range.
From an unknown member posting about the caddy lifters:
I mounted my magnetic base dial indicator and put it on the oil hole in the rocker arm and began to slowly back off of the bolt that holds the rocker down, watching the dial. When loosening the nut, I saw a sweep of .180" from bottomed out lifter to fully extended lifter. I confirmed that reading by repeating the procedure, only tightening the nut this time. Again, .180". I had heard that .060" was the norm for LS1 lifters; however, I also heard on hydraulic roller lifters to set preload in the middle, which in this case would be .090". I am currently using a pushrod that gives .060" preload with no issues, sewing machine noise is very faint. Hope this info helps out.
HTH,
Last edited by 405HP_Z06; 12-15-2008 at 09:09 PM.
03-01-2009, 12:54 AM
#4
I just measured my pushrod length using my comp 7702 tester. after setting the wipe on the yella terras I find zero lash to be at exactly 7.4" (12 full turns out on the 6.8" checker, each turn being .050") My trickflows came with 7.5PR this seems to be a tad more then the recommended .050-.080" preload. would .100 still be safe?
Im using the supplied .048" shims on the rockers and wipe is very good. I was going to run it like that and never look back but I considering the amount of preload my 7.5 pushrods will give me, I could stand to add a little more shim to make wipe even better. where can i find more shims?
03-01-2009, 09:32 AM
#6
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You need to read the directions that came with the rockers. My friend just installed YT's and he told me there was supposed to be only 1/2 to no more than 1 turn from zero lash to 25lb/ft.1 turn equals .040"
FWIW my friend had to use 2 shims to get the best wipe. He also had to notch his AFR heads so the PR side of the rocker would clear. Also, he had to buy 1/2" spacers for the valve covers so the YT's would clear the baffles.
FWIW my friend had to use 2 shims to get the best wipe. He also had to notch his AFR heads so the PR side of the rocker would clear. Also, he had to buy 1/2" spacers for the valve covers so the YT's would clear the baffles.
03-01-2009, 11:13 AM
#7
The directions that come with YT rockers SUCK! If your using non-adjustable bolt down rockers, pushrod length is the only way to adjust lifter preload.
Hopefully Vettenuts will join the conversation, he has a great write-up about setting wipe and pushrod length with these rockers.
Hopefully Vettenuts will join the conversation, he has a great write-up about setting wipe and pushrod length with these rockers.
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03-01-2009, 02:34 PM
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I agree the YT directions suck, and so does YT customer service. My buddy tried unsucessfully for a couple of weeks to contact YT in Australia via email and their only US rep in Mississippi to no avail. Never a response. It may be a good product but they won't get a sale from me!
Gotta say .100 preload is nuts. My HS rebuilds at 1 1/4 turns, .050, is the limit.
Gotta say .100 preload is nuts. My HS rebuilds at 1 1/4 turns, .050, is the limit.
03-01-2009, 04:54 PM
#9
The directions that come with YT rockers SUCK! If your using non-adjustable bolt down rockers, pushrod length is the only way to adjust lifter preload.
Hopefully Vettenuts will join the conversation, he has a great write-up about setting wipe and pushrod length with these rockers.
Hopefully Vettenuts will join the conversation, he has a great write-up about setting wipe and pushrod length with these rockers.
the thing is i dont know where to get additional shims to further adjust wipe. I realize there basicly just washers but i dont have a way to measure that Im using all the same sized shims.
04-23-2013, 06:30 AM
#10
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I just have 2.5 miles on a 6.0 with 5.7 heads ported and polished.springs say 1.8 from machine shop.have a pretty detonate noise in intake area.lifter not pumping up.or has already bent a pushrod? If it is not pumping up can it go away.seems to get quiet after it idle for a few. But hear it when I put in gear.help?
04-23-2013, 07:22 AM
#11
A suggestion... I just have 2.5 miles on a 6.0 with 5.7 heads ported and polished.springs say 1.8 from machine shop.have a pretty detonate noise in intake area.lifter not pumping up.or has already bent a pushrod? If it is not pumping up can it go away.seems to get quiet after it idle for a few. But hear it when I put in gear.help?
