Valve lash question....

-
carls72dart

carls72dart

Well-Known Member
Joined
Dec 31, 2008
Messages
368
Reaction score
28
Location
massachusetts
Hi Fabo, I'm in need of your help once again....I have a 1972 340 engine with a crane hydraulic cam & lifters. I also have 273 adjustable rocker arms.

My question is this: can someone explain in words or maybe a video, what "resistance" means, while spinning the pushrod???

Is it from very loose to feeling just a slight resistance or right before I can no longer spin the pushrod?

Any and all help is greatly appreciated.....Thank you in advance :)
 
hydros need preload which is the opposite of lash. Usually .020-.060 of compression of the lifter is about right. Adjust the rocker onto the pushrod while turning the pushrod in your fingers. when you feel it just start to bind (slightest resistance), your on it. Now turn adjuster 3/4 turn more so your compressing the lifter. You should be OK after that. They say 1/2 to 1 turn so split the difference.
 
Yes sir! Hydraulic lifter preload is pretty forgiving. you can feel the play in the rocker arm as well when you are less than zero lash. You can also wiggle the pushrod up and down until the play is gone then adjust a half to a full turn.


pishta said:
hydros need preload which is the opposite of lash. Usually .020-.060 of compression of the lifter is about right. Adjust the rocker onto the pushrod while turning the pushrod in your fingers. when you feel it just start to bind (slightest resistance), your on it. Now turn adjuster 3/4 turn more so your compressing the lifter. You should be OK after that. They say 1/2 to 1 turn so split the difference.
Click to expand...
 
Pishta, when you say .20-.60 thousands clearance, is that measured from the top of the pushrod cup and bottom of the rocker?

I tried both methods and still getting a lot of chatter....guess I didn't preload them enough...I'll try again in the morning..
 
Is it a new cam/ and or new lifters? If so adjust them loose and readjust after you get things broke in. The lifters will pump up and then you can get a accurate feel for the zero lash. I hate to say it but hydraulic cams really don't need adjustable rockers. They are just a pain. and they take different pushrods than solids or non adjustable hydraulics.
 
toolmanmike said:
Is it a new cam/ and or new lifters? If so adjust them loose and readjust after you get things broke in. The lifters will pump up and then you can get a accurate feel for the zero lash. I hate to say it but hydraulic cams really don't need adjustable rockers. They are just a pain. and they take different pushrods than solids or non adjustable hydraulics.
Click to expand...

Mike, thanks for getting back to me. I bought the engine from a fellow fabo member. It was rebuilt with 300 miles on it. When I installed it in my Dart, I heard a little tapping. Figured I'd adjust the valve train...now I have more tapping. Trying to figure it out on my own, without having to tow it somewhere....
 
69_340_GTS said:
Do you know what kind of lifters they are? Some of them always 'tick', Rhoads for example.
Click to expand...
It's a crane cam and crane lifters...was just a slight tick before I tried adjusting them. Now alot of ticking. I know my adjustment is off, just trying to get.it right and get my car on the road....
 
carls72dart said:
It's a crane cam and crane lifters...was just a slight tick before I tried adjusting them. Now alot of ticking. I know my adjustment is off, just trying to get.it right and get my car on the road....
Click to expand...
Carl, it makes a mess and it's pretty tricky to do but I have adjusted them with the engine running. Back them off till they clatter and tighten them a half to full turn. The hard part is fighting with the adjusters as they are moving. even worse with the Crane replacement rockers as they have lock nuts. You can fight with those too it's just tough and as I said earlier it makes a oily mess. Heck, the Chevy guys have been adjusting rockers that way for years except their hold down nuts don't move because they are on the pivot and not on the valve end of the rocker. tmm
 
toolmanmike said:
Carl, it makes a mess and it's pretty tricky to do but I have adjusted them with the engine running. Back them off till they clatter and tighten them a half to full turn. The hard part is fighting with the adjusters as they are moving. even worse with the Crane replacement rockers as they have lock nuts. You can fight with those too it's just tough and as I said earlier it makes a oily mess. Heck, the Chevy guys have been adjusting rockers that way for years except their hold down nuts don't move because they are on the pivot and not on the valve end of the rocker. tmm
Click to expand...

Mike, thank you. I'm going to try again in the morning. I'm still working on figuring out, how hard the pushrod will be to spin, before I add the 1/2 turn of preload....
 
Are you following the correct sequence for adjusting?
312P4452989.jpg
 
You mentioned clearance. there is NO clearance unless you can wire mic the plunger depth on the lifter itself! Tighten the rocker until you can feel the pushrod drag a little , or just jiggle it and tighten until you cant jiggle anymore, then tighter MORE for 1/2 to 1 turn. Opposite of a solid lifter where you do the exact opposite (tighten until you get lash to 0 then LOOSEN .012 or whatever) Some lifters tick by design (high bleed style) but most pump to (maintain) 0 lash and stay there making the valvetrain 'silent'. Your preloading a flimsy spring in an empty lifter, but the law of hydraulics state that a fluid cannot compress, and once the fluid (oil) is pumped into the lifter, the check ball stops the fluid from escaping on the lift cycle, making it a solid uncompressable lifter that can expand to take up valvetrain differences and thermal expansion. Not a bad system at all.
 
I don't spin the pushrod. To me, that's too vague. I move the pushrod up and down between the rocker and lifter until all the movement is taken up. I call that zero. Then, I adjust the rocker adjuster 1/2 to 1 turn down.
 
pishta said:
You mentioned clearance. there is NO clearance unless you can wire mic the plunger depth on the lifter itself! Tighten the rocker until you can feel the pushrod drag a little , or just jiggle it and tighten until you cant jiggle anymore, then tighter MORE for 1/2 to 1 turn. Opposite of a solid lifter where you do the exact opposite (tighten until you get lash to 0 then LOOSEN .012 or whatever) Some lifters tick by design (high bleed style) but most pump to (maintain) 0 lash and stay there making the valvetrain 'silent'. Your preloading a flimsy spring in an empty lifter, but the law of hydraulics state that a fluid cannot compress, and once the fluid (oil) is pumped into the lifter, the check ball stops the fluid from escaping on the lift cycle, making it a solid uncompressable lifter that can expand to take up valvetrain differences and thermal expansion. Not a bad system at all.
Click to expand...
Just want to thank you for explaining it like that.
 
RustyRatRod said:
I don't spin the pushrod. To me, that's too vague. I move the pushrod up and down between the rocker and lifter until all the movement is taken up. I call that zero. Then, I adjust the rocker adjuster 1/2 to 1 turn down.
Click to expand...
Not that it matters from me but I agree. The pushrod can still be spun even when the lifter is preloaded, so just take your time and do like rusty said.
 
Just a follow up to today's adjustment. I moved the pushrod up/down, until no more play. I went a full turn today and still have a lot of clatter....

Am I better off pulling the hydraulic cam and installing a solid flat tappet cam and lifters?
 
Maybe a couple lifters collapsed or not pumping up ? In my valiant I have a comp 260 cam (hydraulic flat tappet) and 273 rockers and its quite as a mouse. The 360 that Bob Lambeck built for my barracuda
has a custom grind hydraulic roller cam with johnson roller lifters and comp ductile iron rockers. It sounds like a sewing machine ( but hauls serious *** ) Have you tried pushing down on the pushrod side of the rocker after its warmed up to check for lifters that aren't pumping up ? Call Crane and ask how much preload they the want for the lifters. Johnson wants .035 plus or minus .010
 
Pull the valve covers back off and rotate the engine by hand. Look at the relationship between the top of the pushrod cup and the bottom of the rocker arm and make sure there is no contact. You bought a used
engine . Id be checking to make sure the pushrods are the correct length for the preload that crane wants for their lifters
 
iw378 said:
Pull the valve covers back off and rotate the engine by hand. Look at the relationship between the top of the pushrod cup and the bottom of the rocker arm and make sure there is no contact. You bought a used
engine . Id be checking to make sure the pushrods are the correct length for the preload that crane wants for their lifters
Click to expand...
I agree, there is a chance something has interference. There could be a problem if the push rods are so long that the adjustment screw is un-screwed out so much as to cause the ball end to be too close to the bottom of the rocker arm. The adjustment here should be with about 1-3 threads showing through the bottom of the rocker arm body when the preload/lash is set correctly. You don't ever want the push rod hitting the rocker arm itself.
 
malfunctioning hydro lifters can rattle. main cause is the small check ball cannot seat due to metal shaving or debris on the bottom of the lifter. This will manifest itself in a 'spongy' lifter after they are supposed to be pumped solid. some check with a soft mallet on the rockers. atypical hydraulic lifter will hold pressure from anywhere between 12 and 60 seconds after pumping up with engine oil pressure and a few cycles. If they bounce immediantly after shutdown, they are not holding oil, and are clattering because the piston is bottoming in the rocker against the spring only, not the uncompressible oil. You can remove them: pull the circlip , withdraw the piston and spring and remove the small cap under the piston where the tiny spring and check ball is. clean everything and flush bottom of lifter body out with solvent, lots of crap ends up down there. snap everything back together and you should be OK.
 
iw378 said:
Maybe a couple lifters collapsed or not pumping up ? In my valiant I have a comp 260 cam (hydraulic flat tappet) and 273 rockers and its quite as a mouse. The 360 that Bob Lambeck built for my barracuda
has a custom grind hydraulic roller cam with johnson roller lifters and comp ductile iron rockers. It sounds like a sewing machine ( but hauls serious *** ) Have you tried pushing down on the pushrod side of the rocker after its warmed up to check for lifters that aren't pumping up ? Call Crane and ask how much preload they the want for the lifters. Johnson wants .035 plus or minus .010
Click to expand...
I was afraid to run the engine longer than a minute. Wasn't sure if I would do damage to the valves or piston. I'll contact crane today and see what they say. Thank you!
 
AJ/FormS said:
Have you considered that the clatter may something other than valve lash?
Click to expand...
When I first installed the engine and fired it, there was a very faint tapping...once I made an adjustment, it has been off since then.

I did notice last night, after letting the engine sit for 24 hours. The number 7 cylinder, the lifters did not bleed off...all others bled down after sitting 24 hours....
 
You must log in or register to reply here.
-

Back
Top