Login  /  Register  
  Home  -  Forum  -  Classifieds  -  Photos  -  Links     

  << Previous Topic | Next Topic >>Return to Index  

What are the symptoms of a wiped out cam lobe??

April 30 2010 at 4:35 AM

  (Login my68gt)
Members

With all the information floating around regarding ZDDP levels (in particular decreasing amounts in newer oils), I hear warnings against wiping out a cam lobe. How do you know if a lobe is starting to wipe out? What are the symptoms??

 
 Respond to this message   
AuthorReply

Dave Walters
(Login blueoval67)
Members

If I remeber correctly...

April 30 2010, 4:57 AM 

from my days of working in a general repair shop and replacing many camshafts in small block chevies...yuk, you would get a backfire under accelleration. Not like a carb backfire where usually its just one "pop" initially, a bad camshaft will have a repetative backfire every time that worn lobe comes under fire. It pretty obvious.

One more thing, it also will feel down on power.

Dave Walters
http://www.427galaxieregistry.com


    
This message has been edited by blueoval67 on Apr 30, 2010 4:58 AM


 
 Respond to this message   

(Login sandmanf250)
Members

i agree

April 30 2010, 4:12 PM 

good advice

 
 Respond to this message   


(Login MT63AFX)
Members

During break-in, if a lobe even starts going away it's too late to abort and save the.....

April 30 2010, 4:57 AM 

..........cam. Once the engine is in the 2,000 to 2,500rpm range and you notice a change in the 'music', it's too late. Loading your break-in oil with high concentrations of ZDDP lubricants is key, JMO, Rod.

Mickey Thompson's 63 1/2 #997 S/S Hi-Rise 427 Lgt/Wgt Galaxie,
1957 C-600 Cab-over carhauler w/390-4V, 2-speed rear-end
FGCofA member #4908
MCGC member #75

"There will ALWAYS be an FE in my LiFE"

 
 Respond to this message   


(Login qikbbstang)
Members

You just wonder how NASCAR running Flat Tappets "loaded to the max" and super thin oils

April 30 2010, 7:15 AM 

ever make it 500-600+ Miles. I know they run special metals and surface hardening but just the same the crap those cams endure makes a conventional break-in look like Rhomper Room.

 
 Respond to this message   


(Login TorinoBP88)
Members

they dont use lifter. they are a bit 'higher dollar' like $2500 a set n/m

April 30 2010, 11:54 AM 

,

************************************


1968 GT/CS Mustang. 289/c4 (416/4sp TL going in soon.)

Oh and a Bicycle - daily driver to save gas for the 'F'un 'E'xcursions.

 
 Respond to this message   

(Login sandmanf250)
Members

factory stuff man

April 30 2010, 4:17 PM 

a long time ago when i raced snow mobiles , i got into the factory big rig, wow icould never compete with the stuff i found on in that rig.

 
 Respond to this message   


(Login corbins)
Members

missing

April 30 2010, 5:06 AM 

In my cougar with a comp 270 -it developed a minor miss that I chased with wires, dizzy,plugs , carb adjustements etc. Could get it better , but would always break down at higher rpms, could never get it to pull hard above 4600 rpms. Friend actually noticed a rocker arm not moving one day when the breather was off. Hole through the bottom of #6 intake lifter...

 
 Respond to this message   


(Login 66Bird)
Members

Mine was farting

April 30 2010, 6:28 AM 

When I lost #3 exhaust, it started farting through the carb. Not a back fire, but more of a fart sound. Was much worse under load. Happened after about 4-5 hours of run time.
Second time, I was adjusting rockers after break in run. Noticed #4 intake was loose, and not rotating. Engine still ran good, but as others stated, the damage was done.

 
 Respond to this message   
Gary B
(Login Garyford)
Members

No running symptoms

April 30 2010, 7:28 AM 

My son bought a used motor with several completely flat lobes. We didn't know it and the thing ran good below 3000 rpm. Under heavy load or above 3000rpm it would pop. Because it ran so well it was difficult to diagnose. Seeing the cam, it is surprising it ran at all.

I believe he finally diagnosed it by measuring travel at the rocker arms.

Gary B

 
 Respond to this message   
e. philpott
(Login pooreric)
Members

it depends if its a intake or exhaust lobe

April 30 2010, 9:00 AM 

intake lobe is a weak or dead cylinder .... exhaust lobe will pop out the carb

 
 Respond to this message   

Pete
(Login tort1325)
Members

Can you wipe out

April 30 2010, 1:18 PM 

a cam lobe with hydraulic lifters and non-adjustable rockers?

 
 Respond to this message   


(Login d_ford)
Members

Re: it depends if its a intake or exhaust lobe

April 30 2010, 6:14 PM 

I experienced a popping type of backfire in my tunnel port. Found one lobe wiped so I had my engine builder install a new camshaft. It ran great for several miles and then started doing the same thing again. We are assuming it wiped another lobe on the new cam. He hasn't been able to get it back in the shop yet to know for sure but we're wondering if possibly the valve springs are too stiff to break in a new cam? We added the ZDDP additive and did the break-in correctly. Hope to get it back in the shop soon so we'll know what it is.

 
 Respond to this message   


(Login jimmystang)
Members

I reckon cam break-in is a load of crap.

May 1 2010, 2:47 AM 

I just think this whole thing about cam break-in is just B/S.
I was a diesel mechanic for many years and there is no such break-in procedure with diesels in my day. They were all flat tappet camshaft engines. Is there any more pressure at the lifter/cam lobe at idle than at 2000 rpm? It would be negligable if any.

Sure with higher lift cams there may be slightly more pressure but really, how much more?
I think some other problems may be more of a factor like lifter clearance which stops the lifter turning that is detrimental.
There are many myths in the automotive world and I believe this is one of them.

I think it is a "cop out" clause by camshaft manufactures because they can't or won't make materials to handle these applications.

Here in OZ in 1981 we had a 6 cyl Ford crossflow engine that wore cams & lifters fast. There was a grind that fixed that and Ford endorsed it. This was a std engine with a std cam & lifters and this new grind fixed the problem. There was no run in procedure.

Tell me if I'm wrong.........

 
 Respond to this message   

Rod C
(Login MT63AFX)
Members

The issue is that ZDDP has been removed/reduced in oil for cars. Diesels...........

May 1 2010, 4:08 AM 

...........have had large amounts of the ZDDP to this day. I believe the Rotella that people now recommend is made for diesels, JMO, Rod.

Mickey Thompson's 63 1/2 #997 S/S Hi-Rise 427 Lgt/Wgt Galaxie,
1957 C-600 Cab-over carhauler w/390-4V, 2-speed rear-end
FGCofA member #4908
MCGC member #75

"There will ALWAYS be an FE in my LiFE"

 
 Respond to this message   


(Login Mario428)
Members

Diesels have no spring pressure

May 1 2010, 11:08 AM 

They onlt have to rev to 2700 max, takes no valve spring to do that. Plus as someone else said they use high ZDDP in their oil.
Cams having issues is not BS, it is a real problem now that the oil changed. Happening way too often to be BS.

 
 Respond to this message   


(Login jimmystang)
Members

Your right Mario

May 1 2010, 6:09 PM 

Slower revving diesels do have lesser spring pressure but Cummins 12 litre engines (back in the eighties)use an injector cam lobe to actuate each injector. Now that is real pressure on a cam lobe. They do use roller lifters though.
I enquired here in Australia about the ZZDP levels. Austrailan oil companys can still keep this stuff in their oils.
He told me in the US they had to remove it but it was replaced with other lubricants that will still do the same job & meet their emmission targets.

 
 Respond to this message   
Current Topic - What are the symptoms of a wiped out cam lobe??
  << Previous Topic | Next Topic >>Return to Index