Shaved heads and valves wont shut
09-12-2010, 10:52 AM
#21
You are not on the base circle. See bold below. You have the exhaust valve fully open, in one video the spring in compressed more than the other so the cam moved.
If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.
If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.
09-12-2010, 11:45 AM
#22
Thank you for the quick response. I did it again, I turned the crank clockwise until the exh valve just started to open and did the whole thing again. Still came up to 1/4 turn. I stuck in a stock pushrod I had here and did it again, came up to 1/4 turn.
Also I didnt turn the motor between the 2 videos, but i guess something could have moved. Maybe different camera angles?
Also I didnt turn the motor between the 2 videos, but i guess something could have moved. Maybe different camera angles?
09-12-2010, 12:18 PM
#23
Here is another video showing what i was just explaining. This was with a stock 7.400 ls1 push rod. It goes 1/4 turn past "zero lash" which means that I need a longer pushrod... which is impossible. Just for fun, I checked compression on that cyl. It was 85psi. I loosened the rocker bolts (I/E) 1 1/2 turns and it now has 215psi, so I dont think I need a longer pushrod. I know I'm doing something dumb here, I just dont know what.
http://s12.photobucket.com/albums/a2...t=JULY2010.mp4
http://s12.photobucket.com/albums/a2...t=JULY2010.mp4
09-12-2010, 12:57 PM
#25
yes, the stand is all one peice and it is def under the rockers.
Here is another video of me tightening the rockers down on one cyl. You'll notice that when i tighten them, both springs compress and both valves open. Base circle or not, both valves should not open that much at the same time.
http://s12.photobucket.com/albums/a2...Y2010001-1.mp4
Here is another video of me tightening the rockers down on one cyl. You'll notice that when i tighten them, both springs compress and both valves open. Base circle or not, both valves should not open that much at the same time.
http://s12.photobucket.com/albums/a2...Y2010001-1.mp4
09-12-2010, 01:38 PM
#28
One suggestion based on watching your video. Rather then wiggling the rocker side to side, gently lift the tip and so the rocker makes a "tick" "tick" sound on the valve stem, tighten until the "tick" "tick" just goes away and use that as zero lash and try again. Personally, I always found the side to side or rotation of the pushrod to end up with the setup actually deeper then zero lash, especially with several static adjustments where the oil made have been bled from the lifter.
09-12-2010, 04:25 PM
#29
Here is another video showing what i was just explaining. This was with a stock 7.400 ls1 push rod. It goes 1/4 turn past "zero lash" which means that I need a longer pushrod... which is impossible. Just for fun, I checked compression on that cyl. It was 85psi. I loosened the rocker bolts (I/E) 1 1/2 turns and it now has 215psi, so I dont think I need a longer pushrod. I know I'm doing something dumb here, I just dont know what.
http://s12.photobucket.com/albums/a2...t=JULY2010.mp4
http://s12.photobucket.com/albums/a2...t=JULY2010.mp4
as crazy as this soundstry this.... dump a qt of Rislone oil teatment in the engine and drive it a few miles. If its dirt clogging the lifters it work its way out. good Luck
09-12-2010, 05:07 PM
#30
I think your lifters have oil on them!! can you move the rockers up and down?? tighten all the rocker bolts down crank the engine 3-5 times and it will push out the oil from the lifters and then start checking again I have .025 milled heads and 7.375 pushrods I did used the Pushrod Checking Tool and that is what it call for!! fallow this procedure that vettenuts posted on another thread
09-13-2010, 05:50 AM
#34
yes, the stand is all one peice and it is def under the rockers.
Here is another video of me tightening the rockers down on one cyl. You'll notice that when i tighten them, both springs compress and both valves open. Base circle or not, both valves should not open that much at the same time.
http://s12.photobucket.com/albums/a2...Y2010001-1.mp4
Here is another video of me tightening the rockers down on one cyl. You'll notice that when i tighten them, both springs compress and both valves open. Base circle or not, both valves should not open that much at the same time.
http://s12.photobucket.com/albums/a2...Y2010001-1.mp4
Put 7.4 pushrods in #1 if you have them, torque to 22 lb ft., rotate the engine by hand until the intake valve is closed and the exhaust valve just begins to move, loosen the intake rocker, hand tighten to zero lash, torque to 22 lb ft and count the turns.
09-13-2010, 06:58 AM
#35
I worked on a engine that ALL the lifters had this exact same issue. when i pulled it apart every lifter had small amounts of dirt in them.
09-13-2010, 02:23 PM
#36
First off you are working in #3 in that video not #1. You are obviously not on the base circle if both moving.
Put 7.4 pushrods in #1 if you have them, torque to 22 lb ft., rotate the engine by hand until the intake valve is closed and the exhaust valve just begins to move, loosen the intake rocker, hand tighten to zero lash, torque to 22 lb ft and count the turns.
Put 7.4 pushrods in #1 if you have them, torque to 22 lb ft., rotate the engine by hand until the intake valve is closed and the exhaust valve just begins to move, loosen the intake rocker, hand tighten to zero lash, torque to 22 lb ft and count the turns.
09-13-2010, 04:29 PM
#38
How much do you trust the machine shop?
Where they milled to much?
If seats and valve faces both were ground excessively would make the the valve stem higher, that will lead to pushrod length issues.
Just some stuff to think about. Do you have access to a set of stock heads so you can do some measurements?
Where they milled to much?
If seats and valve faces both were ground excessively would make the the valve stem higher, that will lead to pushrod length issues.
Just some stuff to think about. Do you have access to a set of stock heads so you can do some measurements?
09-13-2010, 05:50 PM
#39
I have done this, and i have re-evailuated my opinion of zero lash, but i still get between 1 and 1.5 turns to torque which means these pushrods are the right length. But when I go to crank it over and do a compression check I have about 75-110psi. I can go around and loosen all the rockers 2 turns and I have 225psi.
09-13-2010, 05:51 PM
#40
Its tough to say, I've had them do work for me before, i assume its right, but who knows. I do have some spare stuff around, a complete ls1(still together) and 5.3l heads. I am buying an adjustable pushrod tomorrow(or weds), so hopefully I can start seeing some light here.