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Author
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Topic: cam runout & bearing destruction
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Fastback
Journeyman Posts: 28
From: Livonia,MI
Registered: Dec 2001
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posted 12-20-2001 05:28 PM
   
What is an exceptable cam runout spec? I have up to .0025 on a cam with 300 miles on it. All 5 cam bearings are destoyed within this short time and I have had an odd valetrain noise with this rebuilt engine which is why I tore the engine back down. Ford has a spec of .005 max runout but I cant believe that this could be allowed without tearing up the cam bearings. I found another spec in a engine rebuilding book I have with a .0015 max spec but it is not a Ford book. I cant find any other reason why the bearings would be destoyed in a short time unless the bearing clearance was to small.
Fastback
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Moneymaker
Administrator Posts: 25883
From: Lyons, IL, USA
Registered: May 99
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posted 12-20-2001 05:46 PM
Welcome to M&M fastback  . What engine are we talking about? A maximum of .002 run out on a flat tappet cam is all that I have ever seen. It seems as though there is a lublication problem. Possibly the cam bearings were not proporly lined up with the journal holes.  ------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link
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Tom G
Gearhead Posts: 587
From: Bethlehem, Pa USA
Registered: Nov 2001
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posted 12-20-2001 10:06 PM
Money maker seems to have a point about the cam bearings not being lined up. I wiped out a cam and afew other parts on a 66 428 that was supposedly rebuilt by NASA machinist, must have been an off day for him. Only cam that I have seen that have a major concern with thrust clearance are sb chevys. Not much interested in them though. I have also seen too high a valve spring pressure wipe out a cam on breakin if you don't put asofter set of springs to breakin the cam. This is all I can come up with as to the problem without seeing the bearings or the thrust plate wear indications.------------------
67 Mustang F/B 70 351C 4V 4 speed. Project at the moment though on the street.
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Fastback
Journeyman Posts: 28
From: Livonia,MI
Registered: Dec 2001
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posted 12-20-2001 10:59 PM
The troublesome engine is a street 351C. I am 100 percent positive that all the bearing slots were lined up in the block properly. The cam was well lubed when installed and the motor was primed before starting. I have the engine all dismantled at this point and have looked at the entire oil system and found no resrtictions at all. I also recleaned the entire block and all parts very well before it was assembled, knowing dirt will destroy an engine quickly. The cam bearings started to melt around the cam journals and I could not even pull the cam out. I had to remove the rear plug and tap the cam out with a hammer. 4 out of 5 oil hoes were restricted from melted bearing material. I dont know if the runout was on the cam when I installed it or after the bearings got destroyed. The cam is a new Crane flat hyd. Should I lable this cam as junk and call Crane? Any more ideas? I want to make sure I got this problem solved before I fire up the engine again.
Fastback
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SteveLaRiviere
Administrator Posts: 43151
From: Saco, Maine
Registered: May 99
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posted 12-21-2001 09:29 AM
Were the bearings installed in correct order? Many people don't realize the cam journals decrease in size as you go down the cam.To determine if the cam is still good, I'd go by the journals' finish, exact size, and if it's been blued and lost it's heat temper, {if it's been annealed} in addition to runout. ------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC Christmas shopping? Why not use the
M&M Bookstore?
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Just Strokin
Gearhead Posts: 754
From: Tuscaloosa, Alabama
Registered: Dec 2001
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posted 12-21-2001 01:30 PM
.0025" is not out of specs for cam runout. Even if the spec is tighter, the cam is not grooved for oil like the old FE motor, so, even if the cam walked more, it shouldn't cause a bearing problem.Did the cam rotate freely when installed with no lifters or timing chain? What do the rod and main bearings look like? What did the lifters and cam lobes look like? What was the oil pressure when the motor was running? Where did you measure this oil pressure? Front by filter or rear of manifold? Did you by chance install an oil restriction kit for the cleveland? If so, could this be your problem? Seems like it wasn't recommended for a hydraulic cam. Crane use to have an exchange program. Not sure if it covered anything but maybe high dollar roller cams. I exchanged a roller cam back in 96 for $170 for one a roller lifter broke and destroied.
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Fastback
Journeyman Posts: 28
From: Livonia,MI
Registered: Dec 2001
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posted 12-21-2001 05:28 PM
I would have to assume the bearings were in proper order. There is no numbers on the bearings but will have to assume the cam would not fit if they are out of order. I believe there is .015 difference between the bearing sizes. I have measured the journal size and it is right on. It did not seem to be a problem at the time maybe a little snug fit. The rest of the bearings look good. I used no oil restricters in the engine like a lot of guys do. My oil presure was good at 80 psi coold to 60 psi warm idle taken at the rear of the motor.
Fastback
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kid vishus
Gearhead Posts: 6098
From: middle of NC
Registered: Oct 2000
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posted 12-21-2001 08:30 PM
I would rule out an oil pressure problem. I run the restrictors, mine is 100 psi cold, and about 40 warmed up real good (taken at the rear of the block).
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Moneymaker
Administrator Posts: 25883
From: Lyons, IL, USA
Registered: May 99
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posted 12-22-2001 10:47 AM
Were there restrictors installed in the block? ------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link SANTA HIT MAN & X-MAS TREE DESTROYER
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Fastback
Journeyman Posts: 28
From: Livonia,MI
Registered: Dec 2001
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posted 12-22-2001 12:47 PM
No oil restrictors were used in the block.Fastback
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69_sportsroof
Gearhead Posts: 222
From: Camino Calif (yeah, it does snow here)
Registered: Aug 2000
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posted 12-22-2001 03:43 PM
Just saw a footnote in a ford publication (can't lay my hands on it right nowt),that the cleve cam bearings are(were)honed at the factory,also talked to a short track guy who said that they kept an old cam with slots cut into the bearing surfaces for that purpose.since I've always done windsor stuff this is new to me too. But my cleve is under construction as we speak Jay
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Fastback
Journeyman Posts: 28
From: Livonia,MI
Registered: Dec 2001
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posted 12-22-2001 10:07 PM
What does cutting slots in the journals do on an old cam?Fastback
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SteveLaRiviere
Administrator Posts: 43151
From: Saco, Maine
Registered: May 99
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posted 12-22-2001 11:10 PM
It creates a reaming tool to resize the cam bearings. ------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
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kid vishus
Gearhead Posts: 6098
From: middle of NC
Registered: Oct 2000
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posted 12-23-2001 08:47 AM
Surely new cam bearings come sized already? I ahve never had to have any of them reamed, or honed or anything and have never had any problems like that. And with all the blocks I have broke, and blown up, I have had several of them with new cam bearings installed. 
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69_sportsroof
Gearhead Posts: 222
From: Camino Calif (yeah, it does snow here)
Registered: Aug 2000
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posted 12-23-2001 05:31 PM
Kid...I hadn't heard of this either...gotta confess ive mic'd cams and bearings but never checked the bearings after installation maybe i've been luck all these years. Could be tollerance stack-up, bearings onthe small side of allowable, cam on the large side. I've never wiped out cam bearings like that(oh no i find new and creative ways to destroy engines all on my own!)not stirin' stuff just trying to be helpful......besides in northern cali it's SNOWING and i cant go play....Jay
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SteveLaRiviere
Administrator Posts: 43151
From: Saco, Maine
Registered: May 99
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posted 12-23-2001 08:44 PM
I think I only miked the first several cam bearings I changed. Now I just install them and give the cam a spin and as long as it feels right I move on. I'd be more inclined to think Fastback's problem stems from a bearing installed out of sequence.
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'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
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Fastback
Journeyman Posts: 28
From: Livonia,MI
Registered: Dec 2001
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posted 12-24-2001 11:22 AM
I gave the bearings to a guy at work who's father is a retired engineer from Federal Mogul engine bearings. He looked at the bearings and said "there is to much valve spring presure or load on the cam". He said if was an oil issue the bearings would have been destroyed all the way around. My bearings are worn on the bottoms. He also said the runout I have is not that severe. Another response I had from an old mechanic was similar "to much spring pressure or valves were to tight and using roller rockers changes the standard adjusting proceedure". I am using the matched springs and retainers for the cam. This is a mild cam with .510 lift. I here of all these guys with big cams and heavy springs to match on there Clevelands without this problem. How could my mild cam with matching springs be to much? I have adjusted many valve trains before. I have never heard that adjusting roller rockers is different then a standard rocker and I have not had any problems on other engines I have done.I set this one up with 3/4 preload after zero lash. The car ran great with no idle problems. Yes I am using roller rockers and did set the geometry so the roller tip was in the center of the valve tip and minimal movement across the valve tip. I have no bent pushrods and see no sign of the valves hitting the pistons or any mechanical interfearence. I have not checked for the valve springs binding which I guess could be a problem. I did have a strange valvetrain rattle type noise which I could not find which is why I pulled the motor back out and apart. I am not sure if the noise I heard was from the bad cam bearings or another problem that caused the bearing destruction. Any more ideas? Fastback [This message has been edited by Fastback (edited 12-24-2001).] [This message has been edited by Fastback (edited 12-24-2001).]
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