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Discussion Starter · #1 ·
This is going to get long.
I have a freshly rebuilt engine AMC 360. I have less that 10 hours total time on the engine. I've only driven it about 2 miles, and that went fine. I was working on a issue concerning the throttle linkage. I had put a 4 barrel dual plane Edelbrock intake and Carter AFB carb on during the rebuilt. I had to replace the stock throttle linkage to get better control. That was what I was one of things I was doing today when the knocking started. Earlier today I added a mechnical temp. guage. I didn't trust the factory gauge. Prior to this the engine appeared to be running good, especially considering this was my first rebuild. It does not sound like a rod knock. It sounds more like the upper engine. I shut down the engine as fast as I could when the noise started.
Here's what went into the engine:
A Federal Mogul Premium engine kit- this includes new lifters, pushrods, cam, pistons, oil pump gear, bearings (piston, rod and cam) and rings. I went with chromoly rings. I added a new oil pump pickup and replaced 8 of the rocker arm pivots. Those eight appeared to be worn badly.
I had the block worked over. vatted, cleaned, bored. The alignment of the crank shaft bore was checked. I had the machine shop handle the cam bearing and pressing the pistons on the rods. I also had the heads reworked.
More background: I checked all the bearing clearences and they were within specs. I was making 60 pounds of oil pressure at cold idle, 20 + pounds at hot idle. The pressure maintained fine the few times I drove it. I had not checked the oil pressure today. I had just started the engine and was letting it warm up as I watched the temp readings. I installed the temp sending unit but didn't mount the thing into the dash. I left the temp guage dail setting in the engine compartment so I could watch it, and check for any coolant leaks.
After the noise first started, I shut it down. Since the noise sounded like the upper end, I pulled the valve cover. I found one of the new rocker arm pivots had cracked. I went to the parts store and got a new rocker arm set. I checked the pushrods, they were not bent. I then installed the 2 new pivots and the rocker arm bridge. I did a compression test on that cylinder. It was reading @ 150 #'s. The valves appeared to open and close properly. The engine turned over fine, no noise. Drained the oil and replaced the oil filter. I did not see anything in the oil, nor did I appear to loose any coolant. It did not appear that I had exhaust gasses coming back into cooling system. I did not appear to have any gas in the oil.
I started the engine again and the noise was still there. I shut it down before I even took my hand off the key from when it started. I drained the oil again and dropped the oil pan. There was nothing sitting in the bottom of the pan, and the oil still looked brand new. I was looking for loose rod bolts or main bearing caps. The noise appeared to come from the front of the engine, which was were the broken pivot was. I looked at the front four rod caps, all of them looked fine. I pulled the plugs and watched the bottom of the engine as I turned it over with a breaker bar on the crankshaft. I pulled the front main cap. The bearing looked good. I thought it might have been spun. I haven't checked any of the other bearings to see if they had spun.
I stopped doing anything else because I really did not know what to do, or what to look for.
My previous engine had a bad cylinder, with 60 #'s of compression. I could hear the rod knocking in that cylinder. It was a different sound than the sound in the new engine. I lost my access to the shop that I installed and rebuilt the engine in. At least for a long while. So I need to try and diagnose the problem before pulling the engine.
What diagnostics can I do? Pull the rod caps? Pull the rest of the main caps bearings? Pull them using a use a torque wrench to see if they worked out of torque spec? If I check the compression on all of the cylinders, that would eliminate a cam lobe/lifter problem?
My speculation is that it is a loose wrist pin. I don't know how to tell if one is loose. I suspect that would mean pulling the heads to check the questionable piston.

Thanks for any suggestions-Brett
 

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Bummer... the first thin I do is to

1. Remove the plugs.
2. Put a ratchet to the crankshaft pulley.
3. Rotate the engine CW and feel for a bind, listen for a noise.
4. Rotate the engine CCW and feel for a bind or hear a noise.
 

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ARe you sure the timing chain got installed right? If it is off, the top of the piston may be hitting the valves. That would explain the broken rocker arm pivots. Also did you torque the pivots right? Rotating the engine should confirm these two, but the timing chain being off may be it and is sometimes hard to diagnos without pulling the cover.
 
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Engine sounds are a tough nut to crack, especially on a BBS. You've been checking things pretty well, but isolation is the key here. Reproduce the noise, and try shorting the ignition out, in effect "removing the load" in that particular cylinder. This is pretty effective in a single-noise-per-revolution situation; not so effective if its a multiple-noise-per-rev. After the cylinder is located, then I suggest a thorough mechanical inspection (especially a plastigauge).
A wristpin will usually be loudest in a no-load situation (i.e. park or neutral w/ revving down from a slight increase in rpm--almost rattling infrequently like bouncing ping-pong balls). Adding a load (i.e. in drive or powerbrake) will mostly lessen the noise by increasing cylinder load. Note that this is generally speaking, since it largely depends on rod, pin, and piston design.
Lastly, it always helps to have another educated ear listen in. Invite a mechanically sound buddy over (preferably a tech), feed him a beer and pick his brain...err...ear!
Good Luck
 
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My old 258 used to once a year or so make a horrendous upper end knocking noise, then if I let it sit for a day or so it would stop, did this for 10 years. I figured it was just a pumped up or sticky hydraulic lifter.
 

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I had a knock for the longest time on a rebuilt 258 .Drove me F'n- nuts.only happened above 1000 rpm after the temp reached 140 * and went from manifold to ported vac,via the CTO.I checked everything ,vacume/advance,replaced plugs ,wires ,Distributor,dropped the trans to be sure I didn't leave too much end play in the input shaft,....NADA...bought a mechanics stethascopeand isolated the noise to the pan area ...so ....Finally dropped the pan and pulled the rod caps and sure as hell that is what it was ...But the one that was knocking looked better than some of the ones that were not knocking ...so looks can be decieving...

your problem from a BBS diagnosis sounds like a wrist pin or piston .Uneducated guess.Check it with a stethascope see if you can isolate the knock top or bottom end.
Are you sure the knocking and rattling are related the rattling may be from the carb work you were doing while the knock may be piston/pin related
 

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Discussion Starter · #7 ·
Additional Diagnostics

My additional diagnostics turned up some interesting finds. I went back to the residue of the oil in the pan. After everything settled over night little a very small amount of gold/bronze flecks were in the oil. I could see maybe less than 10 pieces. There also was 1 tiny sliver of metal that was the same color.
I pulled the rest of the rocker arms on the head that had the busted pivot. Cylinder # 2 was the one that had originally had a busted pivot. Today, the # 8 cylinder had a pivot that showed a crack when I picked it up. It broke off in my hand. I then decided to pull all of the rockers on the other head, the drivers side. The #1 cylinder was fine. When I pulled the #3 rockers the spring from the valve closet to the front of the engine fell off in my hand. The valve stem was broken at the top of the valve. It doesn't look like the valve fell into the cylinder. But I choose not to play around with it. At that point in time, I knew that both heads are coming off.
Someone made the suggestion that maybe the vlave timing was not set up properly. I believe that I did get it set properly. Here is what I did when building the engine: Replaced the stock Federal Mogul Timing chain with a Car Quest doubel roller. The Double roller had keyways that allowed for 3 degree before, zero and 3 degree after timing. Since I did not know what types of issues would be involved in retarding or advanceing the valve timing, the keyways were installed for zero. I then used the pin count on the timing chain that was in my Haynes manual. I comparted the old chain with the new to ensure that there was no difference in the length between pins. Not knowing if the timing marks on the new gears were off from the stock gears, once the new gears and chain were installed, I held the old gears and chain up and ensured the the old settings matched the new. They did, all of the key ways aligned perfectly with the number of pins given in the Haynes. Hopefully the description of what I did will help someone tell me if i did it wrong. I will say that engine made great power and sounded good until the noise started. The noise didn't start until after the engine had a couple of hours running time.
Oh, when I pulled the spark plugs yesterday, they had black soot on them. It did not appear to be oil. I am familiar with the look of an oil fouled plug from old engine's no compression cylinder. I think the carb was running rich.
I can fix the heads, hopefully the pistons haven't eaten valves. I still need to understand what caused this before I try to get it running again.

Thanks for the replys- I'm hopefull someone can add more advice. I've decided that my local buddies are worthless help. I took my girlfriend's 7 year old with me today. He helped me more today than any of my other buddies. He may not have had solutions but he made a good tool getter, bolt hander and bolt taker. Which was especially helpfull once I slithered under the Jeep to reinstall the oil pan.
Brett
 
G

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Re: Additional Diagnostics

I've built a few engines over the years, and never had one with all the things wrong that you described! That is weird, something is very amiss. Generally, if something goes wrong it is one thing, that then of course may cause a chain reaction of damage, but the separate things you describe are unheard of.
 

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Look very closely at the shavings of the pivot's again... and at the intact pivots. The way you set the timing gears seems fine. You'll know soon enough when you take off the heads. The problem with the broken vavle compounds things and leads me to think the problem is #3 below,. But, again from the description, here are a few reasons for the faiure I can think of:

1. If the shavings are "blued" then the shavings have gotten too hot and failed, that would lead me to think of a lack of oil to the rockers.
2. There could be a problem with the rockers as assembled. Were they new?
3. The Rockers/pushrods were not re-installed in the same order they came off the head during the rebuild.

The fouling on the plugs is likely unburnt fuel. It looks velvety black and has a sooty feel as opposed to oil which would feel oily when rolled between the thrumb and fingertip.
 

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Discussion Starter · #11 ·
Leve,
The pushrods were new. 1/2 of the pivots were new. The previous owner had the #8 cylinder eat a valve. They had the head repaired and put the pivots on backwards. That caused the pivots to wear imporoperly on that head. So I replaced the entire set from the head. I asked questions about reassembling the heads a few months ago. I had mixed up the rocker arms and pivots. TR (I think) had answered that it should be OK. The idea was that most wear is on the pushrod pivot, and since I had new pushrods, they were going to need to wear in either way. I think the prudent course for me is going to be to get all new rockers and the replace the rest of the pivots. If the piston did eat a valve. If it eat a valve- I am not sure what can be done- can pistons be bought a single unit?
Edited comments:
Nothing that I saw looked like it has overheated. I spun the oil pump up with a drill prior to firing the engine. I made sure that it got good oil pressure from the drill. I let the drill run for a few minutes. Every rocker had oil sitting in it. I did not see anything that looked like it was oil starved. I'll go back and look in more detail for that. When assembling the rockers I tried to make sure each one was in the lifter. I pulled all of the pivots out when I inspected the rockers on Sunday. I saw no damage to any of them, no scoring and none appeared bent when rolled on a flat surface. The residue on the spark plugs was velvety.
Could this damage result from an engine overreving? I don't think that I overevved it from under the hood Saturday. But then again, I did not have a tach under the hood to watch the revs from.
 

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If the pistion did eat a valve
I'm sure you'd have know it... those things don't go quietly into that dark, good night. You'd hear that valve hammering against the piston. The piston will have some marks on the top, and perhaps metal gouged out and thrown around the cylinder. If you're lucky it expelled via the valve, if not it scored the cylinder walls. The rod for that pisiton may also be bent if it ate a valve... and that of course leads to possible cranshaft and low end bearing damage.

On the bright
side I doubt it went this far... or again, you'd know it because you'd be cussin' as you removed the engine because the lower end just destroyed itself when the pistion hammered the vavle.

Oh, and you should be able to get a single pistion or rod if needed.
 

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If you do need to replace all your rockers, summit has some rollor tip and pivot rockers for about $160. They are the same as one of the SBC rockers. I don't remember which of the two sizes though.
 

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Discussion Starter · #14 ·
i did just find that a single piston from Sealed Power (their the Federal Mogul brand I used) is available for @ 25.00 dollars. I am not sure that the sound I heard was the valve hammering the piston. On the other hand- there just wasn't that much metal in the oil. So far I am looking at another 220.00 for gaskets (head, intake and exhaust) and rocker arms. Plus the cost of having the heads reworked. Which is much much better than having had the rod go through the side of the block. That's about the brightest spin I can put on this.
 

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Discussion Starter · #15 ·
American performance sells the stock ones for 8 each. The sealed power 2 pivots and a bridge kit is 2.29. The Sealed Power 2 rockers and pivots with a bridge price is 16.50. Would'nt the Summit kit require a roller cam?
 

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I guess the price has gone up in the last 6 months or so. They are now $190. Here is the part number: CRN-11746-16 (They are Crane brand.)

They work with a regular hydraulic camshaft.
 

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Discussion Starter · #19 ·
Next Round of Diagnostics & Disassembly

I was able to remove loosen the intake & exhaust manifolds tonight. Thinks went well until the very end. As I loosened one head bolt my elbow smashed into the corner of the grill. 3 hours later and my elbow is still smarting. As I removed the lifted the intake manifold I realized the trickling sound wasn't the rain. It was the rest of the coolant draining from the head and into my cylinders. I was able to remove the haed with the bad valve. The valve did not drop into the cylinder. It did make 4 different stampings of itself in the valve. The cylinder walls looked great. There were no pieces of metal in the combustion chamber. The inside of the combustion chambers and valves was the same condition as the spark plugs. There was velvety film on everything but the piston walls. I was unable to remove the piston at this time because the ground was to wet from a recent rain storm.
My plan is to drop the head off, have it checked, rebuilt, what ever the new machine shop suggests. Replace the piston and have the rod checked for damage.
The rings have at the most 10 hours on them. They are chromoly rings. The rod bearings have the same time. I'll plastigage the bearings, but should I put all bearings and rings into the engine? I had previously checked the front main bearing and it looked great. I have found only minimal traces of metal in the oil. Traces of metal that I believe were generated by the normal break in wear and tear. Any suggestions on this?
 

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Discussion Starter · #20 ·
The verdict is in on the cause

I have found 3 (possibly 4) different torque values for the rocker arm bolts. At this point in time, I'm not sure which one I used. But I bet it was a value that was higher than the actual value.
 
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