Thrill of victory and the Agony of Defeat – Cam bearings destroyed. (NOT the lobes) - Page 5 - Vintage Mustang Forums
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post #61 of 87 (permalink) Old 07-27-2019, 09:21 PM
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I have a seasoned 302 block in the garage and looked at the front cam bearing out of curiosity. It has a groove for the oil in the bearing starting down at the six and going up to about the three o'clock position.
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post #62 of 87 (permalink) Old 07-27-2019, 09:28 PM
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I MIGHT have found the smoking gun though. More to follow shortly
I'm going to use my one time VMF flagrant foul flag...I've been on pins and needles waiting to hear what you found

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post #63 of 87 (permalink) Old 07-28-2019, 11:30 PM Thread Starter
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I'm going to use my one time VMF flagrant foul flag...I've been on pins and needles waiting to hear what you found

Allen
Sorry! We have been travelling and are now "across the pond". Post coming now
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post #64 of 87 (permalink) Old 07-28-2019, 11:31 PM Thread Starter
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I have a seasoned 302 block in the garage and looked at the front cam bearing out of curiosity. It has a groove for the oil in the bearing starting down at the six and going up to about the three o'clock position.
#1 has that groove but 2 oil holes. All the rest have a single hole and no grooves

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post #65 of 87 (permalink) Old 07-28-2019, 11:39 PM Thread Starter
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Some suggestions and questions for you. Do you have access to a surface plate? You can roll the cam on it to determine if the journals are in line. Did you measure the cam bearing ID after installing them? It seems like too little clearance if you eliminate lack of oil at all bearings as the root cause. Did the timing chain feel tight? What's your cam bearing clearance?
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Tallguy,
Was the timing chain very tight? I had one that was and took out four sets of cam bearings ( two engine builders before me) and I installed the fifth set but the timing chain was SO tight that it would not fit onto the cam stub with"screwing" it on with the cam bolt. I ended up going with a used chain that had "some" play and 7 years later the engine is still running flawlessly.
Randy

Smoking Gun?? I think I have figured out the problem (well, YOU all figured it out). It is the timing chain being too tight. When I reported earlier that the timing chain went on without much effort, that was relative to what effort is to me. Meaning I did not have to hit it with too big of a hammer and once I got it started I was able to walk both sprockets back into place. Chain was tight but given no take up, I thought nothing more of it (now I see I’m darn lucky to not have popped out the rear cam plug last time)

Fast forward to today…. A lot has been suggested and I have done a ton of research and ruled out a lot of suspects. So finally I got everything clean (AGAIN!!) and also extensively measured/mic’d to assess clearances. Started re-assembling the short block, cam bearing in, cam in, crank in. All feel and rotate good. Now I get to the timing chain, one of the prime suspects. I can’t get it to go on by hand. Fiddle with it and not going to happen. Did not want to pound it on like last time, so I pulled up on it with a ratcheting strap from the ceiling to the cam sprocket. Started ratcheting and eventually got it to slide on the cam shaft. I had enough force to get the front of the engine hoist off the ground. Once on I was able to slide the sprockets back without tools. The chain is tight, too tight. See pic. I have 3/32” deflection, and now that I am really thinking about what is happening, there is absolutely too much down force and the weakest links are the babbit cam bearings.

Again really thinking about it, you want no/minimal tension between cam and crank, just enough force to give a good chain tension. I never even rotated the motor this time, as I think it might damage the cam bearings.

Note that the #5 cam bearing last time was not nearly as damaged as the first four so these seems more plausible
So I have to figure out what to buy now. This is a Comp Cams timing set (CCA-2120) of course so maybe it’s defective like all my other Comp parts. Or is my crank/cam centerline off for some other reason. Block was align honed but that should make it looser if anything?

Confidence is way up now bit I am still being vigilant every step of the way. Can’t work on the motor for a couple weeks so it sits bagged, but I’ll report back.

Timing Chain wide1.JPG

Timing chain measureed.JPG

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post #66 of 87 (permalink) Old 07-29-2019, 12:00 AM
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So, time to try another timing set? Assuming that the block has been line honed at some point in its life the chain should be even more slack...

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post #67 of 87 (permalink) Old 07-29-2019, 12:35 AM
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Is it possible that you have the .005 shorter chain that is advertised for align bored and honed blocks? My block was also align bored and honed but it was only to make a foreign set of main caps work. I asked and the shop said a standard timing set should work fine. I decided to try the standard length Cloyes double roller set(I've always run Cloyes) and my chain play is well within the spec. I typically use the index finger caliper gauge, LOL. The .005 shorter chain wasn't required. I've never had to do anything more than just push the gears up on there by hand.


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post #68 of 87 (permalink) Old 07-29-2019, 02:08 AM Thread Starter
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So, time to try another timing set? Assuming that the block has been line honed at some point in its life the chain should be even more slack...
Yes, just researching what might work. Yes it was align honed my my machinist so very strange that my chain is too tight.

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Is it possible that you have the .005 shorter chain that is advertised for align bored and honed blocks? My block was also align bored and honed but it was only to make a foreign set of main caps work. I asked and the shop said a standard timing set should work fine. I decided to try the standard length Cloyes double roller set(I've always run Cloyes) and my chain play is well within the spec. I typically use the index finger caliper gauge, LOL. The .005 shorter chain wasn't required. I've never had to do anything more than just push the gears up on there by hand.
Yes, I do see a Comp Cam -.010 chain offered. Wondering if they screwed up and gave me that. My machinist never mentioned needing a shorter chain. Definitely agree that "by hand" install is a must otherwise you risk being too tight.

Probably going to pick up a Cloyes as I am done with Comp Cams for life due to all the other problems I've had and zero response from them from my complaints.

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post #69 of 87 (permalink) Old 07-29-2019, 02:29 AM
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Ahh.. Another reason why I will NEVER buy a Comp Cams product- no quality control whatsoever. Not the first time I've seen a garbage timing chain from them.

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post #70 of 87 (permalink) Old 07-29-2019, 07:33 AM
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Upon further review, there was no foul on the play.

I certainly hope that solves the issue...so many specs to check it's easy to get complacent with one like the timing chain deflection, especially IF you get the wrong part in what appears to be the correct part numbered box!

Good luck moving forward!!

Allen
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post #71 of 87 (permalink) Old 07-29-2019, 12:48 PM
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Tallguy,
BINGO! What you are showing is too little deflection for sure . 1/4-3/8ths is FINE. The problem with the Cobra engine I did was the chain itself. I substituted the top gears one at a time with others I had and it was still tight. So on went the "experienced" chain and no more problem. The one in your picture looks like a "speed set" that doesn't have "rollers" on the pins in the chain. That style has 100,000 mile durability and was what Ford used on 5.0s in Mustangs and Explorers. There is no need to go to a VERY expensive billet chain set up or the roller thrust plate. Simply having the "play" will end you bearing problems for once and all.
Thanks for listening to my suggestion, it's all about helping others benefit from previous bad experiences.
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post #72 of 87 (permalink) Old 07-30-2019, 01:27 PM
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Ooo apol;ogies and explanations

Tall, please forgive the incorrect clocking comment, I like Randy's idea, and I think you look like you're on the right track. If you're an old FE guy like myself, you're used to cam registers that have a circumferential groove all the way around. In the FE, an SBC and many other engines that have the groove, you wamt the oil outlets at 3 or 4 oclock. But the baby Windsors don't have this groove, and you can't do the 3 or 4 position unless you have grooved brgs. In doing the cam brgs on a 302, I like to have the oil feed in the block lined up with the very edge of the bearing slot so that the oil has a place to come out before straight down 6:00. Some brands of bearings have longer slots than others, but it sounds like you have it figured out. Our Durabonds have about a half inch of slot, the OE Ford brgs in my block in the barn has just a 1/4 round hole, no slot. You guys ARE reminding me why I frequently choose OTHER than Comp when I'm choosing pieces. Glad you have it figured out. LSG
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post #73 of 87 (permalink) Old 08-01-2019, 12:05 AM
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I hope that is the problem (chain), but I have my doubts. So please check the top end closely, particularly the rocker arm slot clearance with the rocker arm stud or other places where a bind might occur. I have only dealt with "silent" chains (not rollers) and can say that every chain I have ever installed goes on tight with each sprocket alternately moved a little at a time until in position. There is essentially no deflection of the chain initially, but it quickly loosens up on a running engine. Why I don't like the chain theory is that the wear into the bearings is extreme and happened in a short period of time. Also, all bearings were damaged. The chain pulling down on the front bearing would tend to pull up on the aft bearing (fulcrum effect over the front bearing). This would have loaded the aft bearing less than it would normally be even with the valve train pushing down on the cam. Damage pattern suggests overload forces from above all along the cam's length. As I said, hope I am wrong. But, keep looking at other possible areas.
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post #74 of 87 (permalink) Old 08-01-2019, 12:42 AM
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The chain pulling down on the front bearing would tend to pull up on the aft bearing (fulcrum effect over the front bearing). This would have loaded the aft bearing less than it would normally be even with the valve train pushing down on the cam. Damage pattern suggests overload forces from above all along the cam's length. As I said, hope I am wrong. But, keep looking at other possible areas.
Bind in the valvetrain would limit lift, not push down harder on the camshaft. And the fulcrum effect would be far less pronounced due to having to overcome spring pressure distributed equally along the entire length of the camshaft in my non-professional humble opinion. But I agree he should continue to inspect and investigate every aspect.

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post #75 of 87 (permalink) Old 08-01-2019, 08:57 PM
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A bind in the valve train (i.e. rocker slots) would absolutely influence pressure exerted on the cam bearings. It would have to be minimal interference being there were no bent pushrods but nonetheless. Think about it. If a rocker slot is even .010" short of full swing the bind is transferred to the cam via pushrod/lifter. Valve spring pressure isn't even a factor. The rocker slot binds before valve reaches full lift. I agree with Bob that a tight chain (most likely) isn't or wasn't the problem. My first thought was dirt/machining debris that was missed on a block clean but being the damage is done, hard to verify. LSG. FE's are one of the few engines that have a radial groove in the block itself for cam oiling. SB Chevs do not. Nor do most all GM's. Rule of thumb with the full grooved cam bearing registers in FE's is position the feed about 2 o'clock. It's the point at which there is little if any pressure between cam journal and bearing allowing good oil flow INTO the tighter clearances. Reason for 2 o'clock vs 10 is rotation so don't ask...…. To the OP. I'd scrutinize ALL of the valve train/oiling looking for telltale sign before dismissing the fault to a tight chain. JMHO.
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