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Define Valve Lash Please.... #1289314
08/21/12 08:17 PM
08/21/12 08:17 PM
Joined: Jan 2003
Posts: 2,530
Nunya CA
CR8CRSHR Offline OP
master
CR8CRSHR  Offline OP
master

Joined: Jan 2003
Posts: 2,530
Nunya CA
Define Valve Lashing...
OK....I am having the most difficult time getting my roller rockers to quiet down on a newly re-built 383. Just some quick particulars...

1965 383 block with stock crank, rods, 516 heads,etc. Pistons are HP slugs and the cam is a mild 2328 from Hughes. I am also using their MOPAR specific roller rockers and push rods with Comp Cams valve springs rated for a max lift of .525. The cam has a max lift @ 1.5 rocker ratio of .518. New valve guides, hardened seats, shims to get the springs equal, keepers and guides. Now before I get hammered for using them, I am running the CAT roller rockers. They are the same ones as on my last 383 build which is exactly the same as this one. I have had no issues with them what so ever.

Any way...I am still getting noise out of the left and right valve covers after lashing the rockers on 3 previous occasions. This time I backed them out fully and then using Don Taylor's Big Block Book which is my build bible, I re-lashed them again. Motor fired right up but I am still getting chatter. Now here is the question????

When lashing the valves/rockers what is the acceptable and most common way of determining the "resistance" when setting the lash. Is it when the rocker adjuster ball is seated in the push rod cup and no longer will move up or down but still turn or rotate while in position?????? And then adding say a 1/2 turn additional to fully set them or...

Using the same above technique, obtain resistance up and down along with the no rotation of the push rod and then a 1/2 turn to set them?

The key word here is "Resistance". I have had them too tight and no engine fire up so that is not the issue now. Just cannot get them to quiet down and it is really getting annoying trying to get them to quit. Other than that, the motor is running and no leaks...unless you leave the valve covers loose on the head and you wind up with an oil spill underneath and smoke in the shop from the oil burning on the exhaust...

Re: Define Valve Lash Please.... [Re: CR8CRSHR] #1289315
08/21/12 08:43 PM
08/21/12 08:43 PM
Joined: Mar 2003
Posts: 4,848
Memphis
HemiRick Offline
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HemiRick  Offline
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Joined: Mar 2003
Posts: 4,848
Memphis
Assuming you're running a hyd. flat tappet cam. You want to find the zero lash point to start, this is the point where there is no freeplay, and no preload. If you just loosened this same rocker a minute ago, wait a while for it to fully pump back up 1st....They have little springs in them. Then once you find zero lash, you want to tighten them an additional amount to set the preload. I like to use 1.5 turns.


Take care,
Rick
68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451
Re: Define Valve Lash Please.... [Re: CR8CRSHR] #1289316
08/21/12 09:18 PM
08/21/12 09:18 PM
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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RapidRobert Offline
Circle Track
RapidRobert  Offline
Circle Track
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
get the up & down movement of the pushrod just to zero then further add in the correct amt of preload


live every 24 hour block of time like it's your last day on earth
Re: Define Valve Lash Please.... [Re: HemiRick] #1289317
08/21/12 09:45 PM
08/21/12 09:45 PM
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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MoparforLife Offline
Too Many Posts
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
Quote:

Assuming you're running a hyd. flat tappet cam. You want to find the zero lash point to start, this is the point where there is no freeplay, and no preload. If you just loosened this same rocker a minute ago, wait a while for it to fully pump back up 1st....They have little springs in them. Then once you find zero lash, you want to tighten them an additional amount to set the preload. I like to use 1.5 turns.


This is true only if you have the lifter on the base circle of the cam (lowest point)







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