Big Block Hydraulic Lifter Adjustment
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1967 Pedal Car Champion
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From: US-PNW
Big Block Hydraulic Lifter Adjustment
I've been working on my 427/390hp and wanted to double check the hydraulic lifter adjustment. Last time I did this was decades ago, using the hot & running method which I always had difficulty identifying when the lifter first became quiet before the preload. I've read a number of threads and watched videos about doing it with the engine off but everyone seems to approach the job with the intake off and can easily grasp the push rods. How in the world does one fit their fingers between the head casting and the pushrod guide plates for #3 and 6 when the intake is installed? Actually most of the intake pushrods are pretty difficult to get a decent hold on. Are there any tricks to this?
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you can get a mechanics stethoscope and put it on the stud and litsen then tighten it and listen again. YOu can loosen it a quarter turn at a time, listen then tighten. you should be able to get it done. You can get the clips that keep the oil from slinging all over the place or use an old valve cover with the center cut out to keep the mess down as well.
Thread Starter
1967 Pedal Car Champion
Joined: Mar 2020
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From: US-PNW
Do you have any tips or tricks on knowing when the intake lashes, on a big block, are set to -0- before the preload – especially for #3 and #6?
Thread Starter
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,137
Likes: 4,248
From: US-PNW
you can get a mechanics stethoscope and put it on the stud and litsen then tighten it and listen again. YOu can loosen it a quarter turn at a time, listen then tighten. you should be able to get it done. You can get the clips that keep the oil from slinging all over the place or use an old valve cover with the center cut out to keep the mess down as well.
Dr. Detroit
Joined: Mar 2012
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From: New Braunfels Texas
Just wiggle the rocker for zero lash.....up and down.....then 1/2 turn.....you really don't have to touch the pushrod.....
I use the firing order method.......with poly-locs in ALL cases.....you never even have to wiggle the rocker even if you have poly-locs.
Don't over think it......zero lash is zero lash.....
Jebby
I use the firing order method.......with poly-locs in ALL cases.....you never even have to wiggle the rocker even if you have poly-locs.
Don't over think it......zero lash is zero lash.....
Jebby
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If they were adjusted correctly before the only thing that would change is a lifter bleeding down or a cam going flat.
It was common years ago if your lifters got loud to run a quart of atf through your engine to clean them up. But I'd make sure your lol has adaquate zinc in it.
It was common years ago if your lifters got loud to run a quart of atf through your engine to clean them up. But I'd make sure your lol has adaquate zinc in it.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
If they were adjusted correctly before the only thing that would change is a lifter bleeding down or a cam going flat.
It was common years ago if your lifters got loud to run a quart of atf through your engine to clean them up. But I'd make sure your lol has adaquate zinc in it.
It was common years ago if your lifters got loud to run a quart of atf through your engine to clean them up. But I'd make sure your lol has adaquate zinc in it.
Jebby
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Thread Starter
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,137
Likes: 4,248
From: US-PNW
If they were adjusted correctly before the only thing that would change is a lifter bleeding down or a cam going flat.
It was common years ago if your lifters got loud to run a quart of atf through your engine to clean them up. But I'd make sure your lol has adaquate zinc in it.
It was common years ago if your lifters got loud to run a quart of atf through your engine to clean them up. But I'd make sure your lol has adaquate zinc in it.
With hydraulics, what effect does a 1/2 turn preload vs. a full-turn have on valve lift or cam/lifter wear? The reason I ask is that the recommendation here seems to be 1/2 to 3/4 turn whereas the GM Service Manual states 1-full turn.
Dr. Detroit
Joined: Mar 2012
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From: New Braunfels Texas
The ONLY reason you go 1/2 turn vs. more is so the lifter plunger is as high as possible in the lifter body….this keeps the lifter fuller and there is less chance for lifter pump up at high rpm…..
1/2 turn is about .025 plunge….
1/4 turn makes noise in most applications but is required on some setups…like offshore boats so they don’t stall when the throttle is slammed shut…1/2 turn will hold the valves open a smidge….and it will barf and stall….
I have lashed one half turn since the 80’s and you should too….
Jebby
Thread Starter
1967 Pedal Car Champion
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From: US-PNW
None. No change.
The ONLY reason you go 1/2 turn vs. more is so the lifter plunger is as high as possible in the lifter body….this keeps the lifter fuller and there is less chance for lifter pump up at high rpm…..
1/2 turn is about .025 plunge….
1/4 turn makes noise in most applications but is required on some setups…like offshore boats so they don’t stall when the throttle is slammed shut…1/2 turn will hold the valves open a smidge….and it will barf and stall….
I have lashed one half turn since the 80’s and you should too….
Jebby
The ONLY reason you go 1/2 turn vs. more is so the lifter plunger is as high as possible in the lifter body….this keeps the lifter fuller and there is less chance for lifter pump up at high rpm…..
1/2 turn is about .025 plunge….
1/4 turn makes noise in most applications but is required on some setups…like offshore boats so they don’t stall when the throttle is slammed shut…1/2 turn will hold the valves open a smidge….and it will barf and stall….
I have lashed one half turn since the 80’s and you should too….
Jebby