lifter preload/pushrod ?
04-13-2009, 06:23 PM
#1
Staging Lane
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lifter preload/pushrod ? I installed a new cam and lifters a few months back and the car makes the sewing machine/tick sound. I double checked pushrod length today with a comp/cams checker 6.80 closed.. I had 9.75 turns to close @..05 per turn i came up with 7.28@ zero lash how much preload should i run with the ls7 lifters.. I was running 7.4 pushrods and i think i was bottoming out the lifter what size pushrod should i use? still using stock rockers
Last edited by y2kc5; 04-13-2009 at 06:47 PM.
04-13-2009, 06:39 PM
#2
may be this will help
Gotcha This is from the link above from Katech on lifter preload:
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.
Vinci recommends two full turns when using Crane adjustable rockers, which equates to approximately .084". This is what I am using
Gotcha This is from the link above from Katech on lifter preload:
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.
Vinci recommends two full turns when using Crane adjustable rockers, which equates to approximately .084". This is what I am using
