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#1
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May Have Found My Clacker
While adjusting my valves this evening I noted a discrepancy in a single lifter on the #2 exhaust lobe.
If you take a look at my attached photo you can see that the set screw on this lifter is sunken in the adjusting nut about 3-4 turns more than the rest of the set screws. This is true of every rocker on the engine which all adjusted identically. I’ve verified the adjuster nut is sitting properly in its seat. I’ve Rolled the engine over several times and set that valve multiple times. I also swapped adjusting nuts and set screw to see if the problem followed. This lifter is also noticeably softer than the others. You can quite easily depress the plunger when it’s on the heel of the cam. Thoughts? I’m wondering if while I have the valley pan off if it doesn’t make sense to purchase a replacement.
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-Jason 1969 Pontiac Firebird |
#2
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At least pull that lifter out and look at the bottom--and the cam lobe. Might be worth pulling that lifter apart to look for debris or other evil.
Last time I had a soft, noisy lifter, the thing had no check ball at the bottom. |
The Following User Says Thank You to Schurkey For This Useful Post: | ||
#3
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Set screw bottoms on rocker stud and if the stud is the same length as others, the Allen screw has to be the same height. If the rocker stud is same length, then the polylock is sitting higher than the others which makes the Allen screw appear farther down. Is the rocker arm shaft sitting with the flat at the top? Just can't tell from the photo if that might be the problem. Now while this would alter the polylock position the final adjustment would still put the centerline of the rocker shaft the same as others and in itself not make noise.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
#4
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The tops of the lifter bores in the blocks are cast at a pretty darn even height, so if you compare that lifters height on the base circle of the Cam to another one sitting on its base circle and this other one sits higher , well you have a worn Cam lobe, lifter or both.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#5
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Quote:
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'71 GTO, 406 CID, 60916, 1.65 HS, '69 #46 Heads 230CFM, 800CFM Q-jet, TH400, 12 Bolt 3.55 '72 Lemans, Lucerne Blue, WU2, T41, L78, M22, G80 |
#6
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Soory, I read thru this too fast and missed that it was higher, that being said this different adjustment needed unfortunately may be due to the Exh valve pounding into the seat or the seat when the head was made and the valve job done was not pressed in all the way and now from the motor running some it has.
If the installed height on the valve is taller overall then that would be the smoking Gun!
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
The Following User Says Thank You to steve25 For This Useful Post: | ||
#7
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I didn't move the entire rocker assembly and pushrod, just adjuster nut and set screw, so I'll give that a try.
I've had the lifter out and a visual inspection doesn't show anything amiss. I don't currently have the tools to properly take one of these things apart, but I can get them. The cam lobe is in good condition, no scuffing, no ridges etc. I do recall when I took this apart that this set screw was down further than the others, so it's likely been this way for a while. It's been about 4 years since I've had the valve covers off this thing.
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-Jason 1969 Pontiac Firebird |
#8
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Double check that the rocker shaft isn’t upside down.
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The Following User Says Thank You to grandam1979 For This Useful Post: | ||
#9
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X2 with Mick
On check the trunion for flat side UP. That's happened on here before. Clay |
#10
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Yeah I've triple checked that. That's what I meant in my original post about verifying the adjusting nut is sitting properly in it's seat. the HS lifters have a machined flat on the trunion that the adjust slips inside of and rests on.
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-Jason 1969 Pontiac Firebird |
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