Need advice on possible lifter noise
08-04-2001, 09:41 AM
#1
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Need advice on possible lifter noise
I just had my heads rebuilt and have put about 400 miles on them and I noticed a tapping noise.
The odd part is that it taps a few times and stops,taps a few times and stops in a rythm. When I accelerate it accelerates. I am use to lifts that tap continuously but not noise with rythm.
Any advice would be helpful.
FYI I did put the vacuum gauge on and the needle stayed steady even when tapping.
The odd part is that it taps a few times and stops,taps a few times and stops in a rythm. When I accelerate it accelerates. I am use to lifts that tap continuously but not noise with rythm.
Any advice would be helpful.
FYI I did put the vacuum gauge on and the needle stayed steady even when tapping.
08-04-2001, 05:35 PM
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Re: Need advice on possible lifter noise (BLT-71)
Hydraulic lifters or mechanical lifters? A hydraulic lifter that is "out of adjustment" will make loud, hollow rapping noise; when it's bad, you will swear that a rod is knocking.
If you have hydraulic lifters, be sure you have the lifters adjusted with one-turn of preload to put the plunger in the center of its travel. You may have lifters that are right on the ragged edge of being out of their normal adjustment range.
If you don't have a service manual, follow this procedure:
Set the number one cylinder at TDC. Neither valve should be moving as the damper timing mark approaches the "0" timing indicator. If either valve is moving, make another full rotation of the crankshaft before lining up the damper mark and the timing indicator at "0".
Adjust the lifters by rotating the push rod with your fingers while tightening the valve adjustment. When the push rod just stops rotating with your fingers, tighten the valve adjustment another full turn. In this crankshaft position, you can adjust the following valves: Exhaust-Cyl 1, 3, 4, 8 Intake-Cyl 1, 2, 5, 7.
Once you have adjusted the valves above, turn the crankshaft another full turn, and line up the damper timing mark with "0" on the timing indicator. You can now adjust the following valves: Exhaust-Cyl 2, 5, 6, 7 Intake-Cyl 3, 4, 6, 8 using the same method as above.
A quicker, easier, but messier way, to accomplish this adjustment is to do it while the engine is idling. With the valve cover off, the oiling action of the rocker arms gets oil everywhere. You can get clips to put on the rocker arms to reduce the mess, but you will still have a mess.
In this procedure, you simply back off on the rocker arm adjustment with the engine idling until the rocker just begins to clatter (I never observed this in practice, my 66 went directly to the "knock" without clatter), then tighten the rocker adjustment until the rocker clatter (or "knock") JUST stops...Then, tighten the rocker adjustment nut another additional turn, BUT do it in quarter turn increments allowing ten seconds between each quarter turn. You can go right down the cylinder bank until you are finished, then do the same to the other side.
If you have hydraulic lifters, be sure you have the lifters adjusted with one-turn of preload to put the plunger in the center of its travel. You may have lifters that are right on the ragged edge of being out of their normal adjustment range.
If you don't have a service manual, follow this procedure:
Set the number one cylinder at TDC. Neither valve should be moving as the damper timing mark approaches the "0" timing indicator. If either valve is moving, make another full rotation of the crankshaft before lining up the damper mark and the timing indicator at "0".
Adjust the lifters by rotating the push rod with your fingers while tightening the valve adjustment. When the push rod just stops rotating with your fingers, tighten the valve adjustment another full turn. In this crankshaft position, you can adjust the following valves: Exhaust-Cyl 1, 3, 4, 8 Intake-Cyl 1, 2, 5, 7.
Once you have adjusted the valves above, turn the crankshaft another full turn, and line up the damper timing mark with "0" on the timing indicator. You can now adjust the following valves: Exhaust-Cyl 2, 5, 6, 7 Intake-Cyl 3, 4, 6, 8 using the same method as above.
A quicker, easier, but messier way, to accomplish this adjustment is to do it while the engine is idling. With the valve cover off, the oiling action of the rocker arms gets oil everywhere. You can get clips to put on the rocker arms to reduce the mess, but you will still have a mess.
In this procedure, you simply back off on the rocker arm adjustment with the engine idling until the rocker just begins to clatter (I never observed this in practice, my 66 went directly to the "knock" without clatter), then tighten the rocker adjustment until the rocker clatter (or "knock") JUST stops...Then, tighten the rocker adjustment nut another additional turn, BUT do it in quarter turn increments allowing ten seconds between each quarter turn. You can go right down the cylinder bank until you are finished, then do the same to the other side.
08-04-2001, 09:33 PM
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Re: Need advice on possible lifter noise (BLT-71)
Oops. Sorry BLT, good advice, but wrong lifters. I just noticed you have an LT-1 (Duh). Sorry, I have no experience with mechanical lifters.
08-04-2001, 09:59 PM
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Re: Need advice on possible lifter noise (Chuck Sangerhausen)
Chuck I am suprized you have not been chastised by some of the members of this forum for suggesting that you can set the valves in a static manner.
08-05-2001, 12:45 AM
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Re: Need advice on possible lifter noise (a smith)
A, I was surprised members of this forum didn't draw and quarter me for not knowing that LT-1s have mechanical lifters, but these are pretty nice guys or else no one is interested in valve lifters. :D :D :D
Actually, A, you CAN set HYDRAULIC valve lifters statically; that procedure is straight out of the chassis service manual. The reason this is possible with hydraulic lifters is that you are only trying to get the plunger in the center of its travel. They have far more tolerance that mechanical lifters which must be adjusted accurately within thousandths of an inch.
Thanks for keeping me on my toes; I thought I had completely gotten away with a faux pas. :lol:
[Modified by Chuck Sangerhausen, 9:46 PM 8/4/2001]
Actually, A, you CAN set HYDRAULIC valve lifters statically; that procedure is straight out of the chassis service manual. The reason this is possible with hydraulic lifters is that you are only trying to get the plunger in the center of its travel. They have far more tolerance that mechanical lifters which must be adjusted accurately within thousandths of an inch.
Thanks for keeping me on my toes; I thought I had completely gotten away with a faux pas. :lol:
[Modified by Chuck Sangerhausen, 9:46 PM 8/4/2001]