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Does this sound right? (PR Length)

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Old Dec 20, 2006 | 07:21 PM
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Default Does this sound right? (PR Length)

Ok, Got a real noticable loud tapping noise on a car I recently put together. Ive thought the pushrods were a little long but they are already short. Heres some specs on the car:

Cartek 2x Heads milled .030
LS6 block Decked .010 (9.230 deck height)
Cometic .040 head gaskets
Harland Sharp 1.7 shaft mounted rockers
Comp 850-16 lifters
7.300 PR is whats there right now

Ok, Using my PR checker with the HS rockers was a bit of a task ecspecially when the motor is still hot. But I inserted the PR checker, screw it up till it hit the rock and got it finger tight, but still loose enough to turn. I ended up with 7.15 turns which times .050= .3575 ok so I add the .3575 to 6.8= 7.1575. Ok so we need a PR thats 7.1575 long at zero lash. I then added .040 for the preload and got 7.1975. Ive personlly never worked with anything this short. Could this be right? So is the 7.300 really to long and I need a 7.200?

Last edited by Z'mnypit; Dec 21, 2006 at 08:03 AM.
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Old Dec 20, 2006 | 07:32 PM
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Originally Posted by Z'mnypit
Ok, Got a real noticable loud tapping noise on a car I recently put together. Ive thought the pushrods were a little long but they are already short. Heres some specs on the car:

Cartek 2x Heads milled .030
LS6 block Decked .010 ( I think, the build sheet it MIA)
Cometic .040 head gaskets
Harland Sharp 1.7 shaft mounted rockers
Comp 850-16 lifters
7.300 PR is whats there right now

Ok, Using my PR checker with the HS rockers was a bit of a task ecspecially when the motor is still hot. But I inserted the PR checker, screw it up till it hit the rock and got it finger tight, but still loose enough to turn. I ended up with 7.15 turns which times .050= .3575 ok so I add the .3575 to 6.8= 7.1575. Ok so we need a PR thats 7.1575 long at zero lash. I then added .040 for the preload and got 7.1975. Ive personlly never worked with anything this short. Could this be right? So is the 7.300 really to long and I need a 7.200?
that sounds to short, around 7.350 looks about right to me.
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Old Dec 20, 2006 | 08:03 PM
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IDK, that is why you have the adj pushrod so you can mesure this stuff, I say the 7.200 sounds right, as long as you know for a fact that you have the lobe your check on the base circle of the cam. I got 7.100s in mine. It all has to with your cam base circle, lifters, rockers, and even you valves, thats why you got a adj pushrod, to make it right.
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Old Dec 21, 2006 | 07:38 AM
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Thanks speedy. Im going to recheck it one last time before I order them. Im positive the valve was all the way closed and the lifter was on the base circle of the cam.

Anyone else?
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Old Dec 22, 2006 | 07:25 AM
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ttt.... Any other opinions?
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