Top end oiling
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by tracdogg2
Yes it would.
Mike
Mike
How easily could that happen during a simple cam change? I know they are hard to move, but I wonder if while installing the cam, one of the cam bearings could have been spun or moved off of it's oil feed hole.
Instructor
Joined: Feb 2006
Posts: 144
Likes: 0
A cam bearing wont just spin unless something is very wrong, most important when installing cam bearings is to center them correct so that the groove is matching the oilinghole. just changing the cam cannot move the cam bearings out of positioning.
most likely you have a problem with your lifters did you go from hydraulic to mechanical cam?
most likely you have a problem with your lifters did you go from hydraulic to mechanical cam?
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
Block is a 74 454. Was oiling fine before I wiped a new cam earlier last summer. Just got around to installing a new one this weekend. I have 65 psi on the guage but little oil to the top. Using all new Comp cams stuff (including pushrods). Any ideas.
Also, using the new roller tip rockers (they don't require a special push rod do they)?
Also, using the new roller tip rockers (they don't require a special push rod do they)?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by Hvymtlc5
Also, using the new roller tip rockers (they don't require a special push rod do they)?
Are the roller lifters designed for that engine and cam? If they are taller than the stock lifters, the oil feed hole will rise up above the lifter bore, and you will lose pressure above the lifters.
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Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
I'm not using a roller cam. I am using Comp lifters, my cam is a COMP XE274. The roller tips were also comp Cams 1.7s. I don't see any reason for problem here, or am I missing something?
Last edited by Hvymtlc5; Nov 20, 2006 at 11:37 AM.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by Hvymtlc5
Maybe you can answer the question for me, because now we're in an area that I'm not to sure on.
Cam was a COMP XE274. The roller tips were also comp Cams 1.7s
Cam was a COMP XE274. The roller tips were also comp Cams 1.7s
I'm not familiar with Comp cams or rollers. When you bought them, was it a kit you saw online and ordered, or did you get it from Comp based on what engine you had? A call to Comp would not be a a bad idea. Tell them what engine you have, when cam and lifters you have, and the symptoms you have. They may have some product info that can help. It's just a long shot that they don't match your oil bores height...but I have seen it before.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by mailbox1024
Oil flows through the push rods, you may want to check for blockage in them. Check for trueness and then clean and blow them out.
That would mean that ALL the push rods have blockage though right? One or two I could understand...but all? Hmm..I guess stranger things have happened.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
I'm NOT a BBC expert.
I understand there's quite a difference between early & later BBC regarding the rear cam bearing / rear cam journal.
I seem to recall this issue & similar thread(s) came up previously w/ Hvymtlc5 ... and that myself/others suggested problem may have roots in the early-late cam bearing/journal area. I realize the difference is documented to occur prior to MY1974. But again ... I suggest there may be a mismatch between this particular block / rear cam bearing / rear cam journal.
I dunno ... early journal/late bearing ... or vsv ... check it out? Heck maybe block is very early but restamped to emulate a later one ... I dunno ... get out the fine toothed comb & exhaust this possibility?
BTW ... maybe it was NOT oiling fine when it wiped a cam earlier last summer.
I understand there's quite a difference between early & later BBC regarding the rear cam bearing / rear cam journal.
I seem to recall this issue & similar thread(s) came up previously w/ Hvymtlc5 ... and that myself/others suggested problem may have roots in the early-late cam bearing/journal area. I realize the difference is documented to occur prior to MY1974. But again ... I suggest there may be a mismatch between this particular block / rear cam bearing / rear cam journal.
I dunno ... early journal/late bearing ... or vsv ... check it out? Heck maybe block is very early but restamped to emulate a later one ... I dunno ... get out the fine toothed comb & exhaust this possibility?
BTW ... maybe it was NOT oiling fine when it wiped a cam earlier last summer.
Last edited by jackson; Nov 21, 2006 at 11:04 AM.
Le Mans Master
Joined: Apr 2005
Posts: 6,339
Likes: 416
From: Seattle Area WA
I beleive that the required groove in the cam's #5 journal surface was a requirement only up to through the '65 big blocks. With that said, did they accidently send you a cam with a groove in your rear #5 cam journal for your newer motor?
I know some big block guys add an oil distribution dripper tube the length of the cam which requires tapping into the back of the block. They do this due to inadequate top end oiling often found in the big blocks. It's probably not a practical suggestion at this point in time but maybe a thought for later. This is additional oiling tube is relatively common in some European hi performance overhead cam engines such as the BMW 5.0 V12 for example.
I know some big block guys add an oil distribution dripper tube the length of the cam which requires tapping into the back of the block. They do this due to inadequate top end oiling often found in the big blocks. It's probably not a practical suggestion at this point in time but maybe a thought for later. This is additional oiling tube is relatively common in some European hi performance overhead cam engines such as the BMW 5.0 V12 for example.
Pro
Joined: Aug 2003
Posts: 530
Likes: 0
From: Victoria Texas
Big blocks with Hydraulic cams are bad about having a air pocket in the oil galley going to the lifters.
The factory fix was to drill a small bleed hole in the two front oil galley pipe plugs behind the timing gear.
I have had this problem before also, and drill all the plugs on BBC that I build now.
I just freshened a 454 from a 78 1-ton truck and the plugs were drilled on it from the factory.
I hope you do not have to pull it back down, but it may save the cam.
There was a tech. bulliten out from GM about this, it was the fix for cams going flat from loss of oil to the top end and the lifters beating the cam lobe to death on start up.
A lot of machine shops do not know this and put solid plugs in the block when they clean them, A friend of mine ownes a shop and I asked him one day about it, he said he drills the plugs on all the BBC that he does, he has been doing it for 25 years with no problems.
The holes are only like .020-.030 just to let the air trapped in there out.
Mark G
The factory fix was to drill a small bleed hole in the two front oil galley pipe plugs behind the timing gear.
I have had this problem before also, and drill all the plugs on BBC that I build now.
I just freshened a 454 from a 78 1-ton truck and the plugs were drilled on it from the factory.
I hope you do not have to pull it back down, but it may save the cam.
There was a tech. bulliten out from GM about this, it was the fix for cams going flat from loss of oil to the top end and the lifters beating the cam lobe to death on start up.
A lot of machine shops do not know this and put solid plugs in the block when they clean them, A friend of mine ownes a shop and I asked him one day about it, he said he drills the plugs on all the BBC that he does, he has been doing it for 25 years with no problems.
The holes are only like .020-.030 just to let the air trapped in there out.
Mark G
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by Skid*MARK
Big blocks with Hydraulic cams are bad about having a air pocket in the oil galley going to the lifters.
The factory fix was to drill a small bleed hole in the two front oil galley pipe plugs behind the timing gear.
I have had this problem before also, and drill all the plugs on BBC that I build now.
I just freshened a 454 from a 78 1-ton truck and the plugs were drilled on it from the factory.
I hope you do not have to pull it back down, but it may save the cam.
There was a tech. bulliten out from GM about this, it was the fix for cams going flat from loss of oil to the top end and the lifters beating the cam lobe to death on start up.
A lot of machine shops do not know this and put solid plugs in the block when they clean them, A friend of mine ownes a shop and I asked him one day about it, he said he drills the plugs on all the BBC that he does, he has been doing it for 25 years with no problems.
The holes are only like .020-.030 just to let the air trapped in there out.
Mark G
The factory fix was to drill a small bleed hole in the two front oil galley pipe plugs behind the timing gear.
I have had this problem before also, and drill all the plugs on BBC that I build now.
I just freshened a 454 from a 78 1-ton truck and the plugs were drilled on it from the factory.
I hope you do not have to pull it back down, but it may save the cam.
There was a tech. bulliten out from GM about this, it was the fix for cams going flat from loss of oil to the top end and the lifters beating the cam lobe to death on start up.
A lot of machine shops do not know this and put solid plugs in the block when they clean them, A friend of mine ownes a shop and I asked him one day about it, he said he drills the plugs on all the BBC that he does, he has been doing it for 25 years with no problems.
The holes are only like .020-.030 just to let the air trapped in there out.
Mark G
Don't suppose you have ever take a pic of this have you? It'd really clear things up to see it.
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
Good info...but engine oiled fine before with original cam (before the wiped one and this new one). I'm going to run it with the covers off tonight to see how bad it really is....may put the stock rockers back in.
