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Old 10th-January-2017, 10:47 AM   #16
kimrobertson
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Quote:
Originally Posted by sbc1320 View Post
Could be lots of things. I've seen a broken piston skirt sound just like a loose rocker.

As far as setting your valves, if you don't know how then learn/ask and don't guess. Not bashing at all, but really serious about this. Don't only learn the how, but the why also.
I really didn't know when I originally built the engine 5 years ago. That's where I think this all began. Shortly after I built engine 5 years ago I set them correctly but only after engine was running. Before starting first time I had them way too tight. I'm guessing damage was done at first start and that first trip around the block after firing it up 5 years ago.

I just installed new rockers and pushrods and set the pre-load correctly and it sounds the same as it has for 5 years only worse I let it run for 5 minutes and tried to re-adjust while running but the noise isn't rockers...But it's not the rockers-- It's deeper...I'm guessing cam and/or lifters.
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Old 10th-January-2017, 11:15 AM   #17
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Before jumping to conclusions, I would do the following:

1. Look closely at your oil pressure. What's min at idle and max? Has there been any changes over time?

2. After adjusting your rockers, look at the height of each rocker nut. Are any nuts threaded down more than others? If so, you likely have a wiped cam or lifter issue.

3. Perform a compression check. All should be around 150 psi (if it's a low compression engine) with +/- 5% variability. If you have one or more outliers, you have an issue to investigate which will likely require tear down.

4. Perform a leakdown check. If you have one or more outliers, you have an issue to investigate which will likely require tear down.

These tests will point you in the right direction....

Kev
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Old 10th-January-2017, 01:37 PM   #18
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It's also possible that you have trash in the lifters. Does it sound like a tick?
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Old 10th-January-2017, 06:45 PM   #19
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Before jumping to conclusions, I would do the following:

1. Look closely at your oil pressure. What's min at idle and max? Has there been any changes over time?

2. After adjusting your rockers, look at the height of each rocker nut. Are any nuts threaded down more than others? If so, you likely have a wiped cam or lifter issue.

3. Perform a compression check. All should be around 150 psi (if it's a low compression engine) with +/- 5% variability. If you have one or more outliers, you have an issue to investigate which will likely require tear down.

4. Perform a leakdown check. If you have one or more outliers, you have an issue to investigate which will likely require tear down.

These tests will point you in the right direction....

Kev
Thanks for the good advice Kev. The oil pressure has remained consistently about20-25 lbs warm idle and 60 lbs.cold fast idle...about 40-45 lbs warm driving.

All the rockers are 4 threads down...uniform. I still want to make sure no discernable difference in rocker arm travel... Next would be the compression check.
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Old 10th-January-2017, 06:48 PM   #20
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It's also possible that you have trash in the lifters. Does it sound like a tick?
It sounds like a tick but a little more serious than say just dirt. Should be very clean inside...will probably find out more as investigation continues.
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Old 11th-January-2017, 08:32 AM   #21
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I've had some "ticks" that ended up as rod knock...... that's why I asked the oil pressure question. I think a compression/leak down will tell you a lot.

Kev
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Old 11th-January-2017, 02:46 PM   #22
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If you've replaced the push rods and rockers and the noise is still there, IMO you need to pull the lifters and check the bottoms with a straight edge. If they're dished you found the problem. I would replace both cam and lifters. If they are good then the problem is deeper. Maybe piston slap or a bad wrist pin/ wrist pin hole. My guess would be wrist pin.
Was the engine rebuilt with all new parts? Can you pin down the noise to one cyclinder? If so, pull the plug wire and see if the loudness/strength changes. Lifter ticks won't change. Piston, wrist pin, bering noise will.
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Old 11th-January-2017, 04:15 PM   #23
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[QUOTE=novaboy009;5250777]I've had some "ticks" that ended up as rod knock...... that's why I asked the oil pressure question. I think a compression/leak down will tell you a lot.

Kev[/QU

Right---I've always watched the oil pressure for that reason...Has been consistently good. Don't think it's a rod bearing.
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Old 11th-January-2017, 04:19 PM   #24
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If you've replaced the push rods and rockers and the noise is still there, IMO you need to pull the lifters and check the bottoms with a straight edge. If they're dished you found the problem. I would replace both cam and lifters. If they are good then the problem is deeper. Maybe piston slap or a bad wrist pin/ wrist pin hole. My guess would be wrist pin.
Was the engine rebuilt with all new parts? Can you pin down the noise to one cyclinder? If so, pull the plug wire and see if the loudness/strength changes. Lifter ticks won't change. Piston, wrist pin, bering noise will.

Actually one tick turned into multiple ticks after changing the push rods & rockers...Hopefully can do more investigation Friday.

Had the pistons and connecting rods and crank checked out when I originally tore down engine...all in good shape then. At that time I needed the pistons turned around on the rods because they were put on backwards by previous owner... Everything was checked out by a reputable machine shop and sound. I'm not thinking those are where the problem is. Hopefully not anyway.
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Old 13th-January-2017, 08:14 PM   #25
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Made a little progress today. Travel for rockers is essentially the same--no measurable deviations... All rocker studs show 4 threads... Was able to get 4 of the easiest cylinders checked for compression... 1--173 2-175 4--180 8--180 May get more time tomorrow.
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Old 13th-January-2017, 09:52 PM   #26
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That all sounds promising. If the other 4 are that good I would just run it as is and live with the noise.
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Old 13th-January-2017, 11:08 PM   #27
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are you sure it isnt a header leak at the head and/or collector leaking?
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Old 14th-January-2017, 03:03 PM   #28
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Compression test completed...Had to disconnect the passenger side header but not too bad. Here are results.

1-- 180 (re-tested this one because gauge wasn't tight enough)
3-- 175
5-- 183
7-- 182

2-- 180
4-- 180
6-- 174
8-- 180

Not sure where this leaves me but hopefully indicates valves are okay...
Could these and the other tests I have done be this good and lifters also be bad?
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Old 14th-January-2017, 07:41 PM   #29
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No bent valves with that compression. With all the rockers moving the same and adjusted the same it is probably all good. The cam in my 406 had steep closing ramps I swear I could hear the valves hitting the seats. Check for exhaust leaks as mentioned before, look for soot around the gaskets on the heads and collectors.
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Old 14th-January-2017, 07:51 PM   #30
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I saw some Chinese replacement lockers make a tick because they weren't slotted enough. They worked fine on stock engines but couldn't handle any RV cam lifts.
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