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valvetrain noise ?????

M

MDSIDMAN

NAXJA Forum User
Location
OREGON
I have a 92 4.0. I just rebuilt the motor. Bored .040 over. Added a Mopar performance stage 2 cam and lifter kit. Question is... I have what sounds like mild lifter noise above 200 rpm's. I was concerned until I listened to a friends jeep with the same cam and a fresh rebuild. Sounds similar but louder than stock. Anyone else have experience with this or insight?? Is it normal or should I be more concerned?
Thanks for any input
By the way it has huge power now so if this is normal I strongly recommend the cam package!!!
 
Mild valvetrain noise isn't unusual when you install a higher lift cam, especially if you also install heavier valve springs.
Did you check the lifter preload when you assembled the engine?
 
Dr. Dyno said:
Mild valvetrain noise isn't unusual when you install a higher lift cam, especially if you also install heavier valve springs.
Did you check the lifter preload when you assembled the engine?
Click to expand...


What is the spec of lifter preload?........... .050"? how much above and below can ya get away with?


HOw much can ya shave off the head/block before this becomes a problem?



Flash.
 
The lifter preload should be between 0.040-0.060". When tightening down the rocker arm bolts, you should need 3/4 to one full turn of the bolt to go from the "zero play point" (where the pushrod can no longer be rotated easily) to the 19lbft of torque specified in the manual. If you need much more than one full turn, you'll need to shim the rocker arm bridges.
 
Dr. Dyno said:
The lifter preload should be between 0.040-0.060". When tightening down the rocker arm bolts, you should need 3/4 to one full turn of the bolt to go from the "zero play point" (where the pushrod can no longer be rotated easily) to the 19lbft of torque specified in the manual. If you need much more than one full turn, you'll need to shim the rocker arm bridges.
Click to expand...


Although i have rebuilt sever chry eng....i haven't dabbled much with the 4.0(will be a stroker when i do!)

the rocker arms are not adj...right? supported on one single shaft?

I have had to do the shaft shimming on a 360 chry, trying to get the comp. up by shaving the head.
When i first put the eng together, it wouldn't start till the rocker shaft shims where installed and then had to go to the next thickness to get the lifter chatter to go away.

that's when i got schooled on the Hyd lifter depth requirement
 
The stock rocker arms are definitely not adjustable, so the only ways to reduce excessive lifter preload are to either shim the bridges or install shorter pushrods.
 
Dr. Dyno said:
The stock rocker arms are definitely not adjustable, so the only ways to reduce excessive lifter preload are to either shim the bridges or install shorter pushrods.
Click to expand...

THANKS!

So is it one long rocker shaft or short individual on for each syl?




Flash.
 
The stock rockers are not mounted on a shaft. They are mounted in pairs on a pedestal (bridge) similar in style to the Ford 5.0 engine and there are six pairs altogether. The shims go between the bridge and the cylinder head where the rocker arm retaining bolts thread through.
 
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