Just got done with a 454 tonight---Pics inside
07-30-2007, 01:36 AM
#21
BBC's are rougher on cams due to the greater rocker arm ratio, and the relatively small diameter of the lifter.
Don't believe all the horror stories about wiping cams on BBC's. People have been building them for years without every (or even a high percentage) flat tappet cam going flat. GM built millions of BBC's with flat tappet cams and didn't have huge issues with it.
Most engine builders agree that most of the cam failures recently can be attributed to the lower zinc levels in oil.
EOS or other zinc additive will take care of this.
I've built probably over a hundred BBC's and never had a flat tappet cam go flat (going to knock on wood now).
Any good machinist knows what to look for when machining and assembling the engine to prevent it.
Don't believe all the internet hype, just because information is more widely available on the internet, doesn't mean the problem is commonplace.
Don't believe all the horror stories about wiping cams on BBC's. People have been building them for years without every (or even a high percentage) flat tappet cam going flat. GM built millions of BBC's with flat tappet cams and didn't have huge issues with it.
Most engine builders agree that most of the cam failures recently can be attributed to the lower zinc levels in oil.
EOS or other zinc additive will take care of this.
I've built probably over a hundred BBC's and never had a flat tappet cam go flat (going to knock on wood now).
Any good machinist knows what to look for when machining and assembling the engine to prevent it.
Don't believe all the internet hype, just because information is more widely available on the internet, doesn't mean the problem is commonplace.
07-30-2007, 01:47 PM
#23
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Originally Posted by jakeshoe
Don't believe all the horror stories about wiping cams on BBC's. People have been building them for years without every (or even a high percentage) flat tappet cam going flat. GM built millions of BBC's with flat tappet cams and didn't have huge issues with it.
Most engine builders agree that most of the cam failures recently can be attributed to the lower zinc levels in oil.
EOS or other zinc additive will take care of this.
Most engine builders agree that most of the cam failures recently can be attributed to the lower zinc levels in oil.
EOS or other zinc additive will take care of this.
07-30-2007, 01:52 PM
#24
Originally Posted by 1997bird
Are you sure that it doesn't have anything to do with the lifter bore angle's?
The lower zinc levels in oil def add to the problem. Along with material issues with the lifters and/or cam cores.
GM definately built their share of flat tappet motors, no doubt. But dont think for a minute they didnt have problems with them.
The 4100 Caddys back in the early 80s were notorious for wiping lobes.
And that was FROM THE FACTORY.
And yes, I realize we're talking about BBCs not 4100s, just sayin....
07-30-2007, 03:46 PM
#25
Originally Posted by 1997bird
Are you sure that it doesn't have anything to do with the oiling system and lifter bore angle's? I've used 1.7 ratio rockers on SBC's without problem's.
OEM production engines are allowed some variation from blueprint. Core shift happens, machining errors, etc.
What we experience when we build a performance engine is pushing the envelope sometimes.
An aftermarket performance cam obviously has a faster rate of lift than a stock cam. When you lift the lifter faster on a flat tappet cam, the lobe travels closer to the edge of the lifter than a slow moving stock cam designed more for reliability.
If the lifter bores are out of alignment very slightly, and you are running a cam that is on the ragged edge of .842" diameter flat tappet capability, it is possibly you could run experience a failure because the cam lobe "digs into" the side of the lifter. That is, it goes past the safe margin designed into the cam. This safety margin is much less on a very fast ramp cam.
Most builders prefer to rebore the lifter bores to a larger size such as .875 or .904 and at the same time they can control the bore placement (blueprint it).
Combine the "edge of the envelope" cams being sold today, 30-40 yr old engine cores with unknown background, and the zinc levels, yes it can be an issue but it is simply not so prevalent as to prevent a person from building a flat tappet BBC.
I don't really subscribe to the theory of huge numbers of bad cam cores. Yes I believe a few may not be properly heat treated, and this shows up as a total failure of every lobe on the cam.
There are only 3 or 4 companies who manufacture the cam cores.
I think there may have been some lifter issues but if you are using a quality lifter, not a huge ordeal either.
How many people here have had to pry a lifter out of the bore when disassembling an engine due to carbon or mushrooming?
07-30-2007, 11:09 PM
#26
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Originally Posted by jakeshoe
The oiling system is basically the same as a Gen I SBC. The lifter bores are not angled any different than a SBC. They are at 45* from center, same as the cylinder bores.
This will be my last post in this thread, as all we are accomplishing is drama for other's to stay tuned to. If you have had luck with flat tappets great, my hats off to you. I just hope that everyone else reading this doesn't think that this is the norm with flat tappets & BBC's.
I found my specs again on most of the prostock lifter bore angle's, here are two common revisions:
45* int & 45* exh
42* int & 48* exh
I would think that you can now see were the problem lie's in wiping out the cam lobes on the intake side.
Last edited by 1997bird; 07-31-2007 at 10:54 AM. Reason: More info!
07-30-2007, 11:29 PM
#27
Originally Posted by 1997bird
That is where you are wrong, a SBC Gen 1 to Gen 2 have a 41* int & exh lifter bore angle. Where the BBC's have a 38.75* int & 45* exh common lifter bore angle. The Gen III/IV SBC's motors(LS1/LS6/LS2/L92/LS7/LS3) have a 45* lifter bore angle.
This will be my last post in this thread, as all we are accomplishing is drama for other's to stay tuned to. If you have had luck with flat tappets great, my hats off to you. I just hope that everyone else reading this doesn't think that this is the norm with flat tappets & BBC's.
This will be my last post in this thread, as all we are accomplishing is drama for other's to stay tuned to. If you have had luck with flat tappets great, my hats off to you. I just hope that everyone else reading this doesn't think that this is the norm with flat tappets & BBC's.
I believe it is the norm since there are thousands of these engine able to run flat tappets cams on a daily basis and they don't fail. Some for hundreds of thousands of miles.
You're not going to run 500 lbs of open spring pressure with a flat tappet and expect it to live long.
Rollers have their advantages and place but it doesn't mean every BBC must be built with one.
08-05-2007, 03:22 PM
#29
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Just saw this. I found out the hard way about flat tappets going flat. i have worn cams out in my Truck motor. But new motor for my project the cam went flat after break in. I have not built a BBC for a while so i wasn't familiar with no Zinc in oil. When i went to machine shop they were not surprised about cam at all and told me about using Diesel oil(rotella's for startup/break in)
08-09-2007, 12:04 PM
#31
Originally Posted by bgblockelcamino
Just saw this. I found out the hard way about flat tappets going flat. i have worn cams out in my Truck motor. But new motor for my project the cam went flat after break in. I have not built a BBC for a while so i wasn't familiar with no Zinc in oil. When i went to machine shop they were not surprised about cam at all and told me about using Diesel oil(rotella's for startup/break in)
08-10-2007, 09:17 PM
#33
Originally Posted by fergymoto
My buddy just bought a house and found out a few days later his wife is pregnant, so the truck has been on hold lately. I'll post up when he gets to it!
Hate to be the prophet of doom, but thats like the worst thing you could do. If its at all close to starting, I would spend the few hours its gonna take to get it fired, and at least try to break in the cam. If you let it sit, the longer it sits, the worse its gonna be.
but WTF do I know, I'm just one of those guys thats never built a BBC or had a cam wipe out. Anybody that tells you its not a problem hasnt built many big blocks.
BTW my experience/resume with big blocks goes back over 2 decades.
08-10-2007, 09:32 PM
#34
Listen man there's nothing I can do about it. I don't have the extra money to go buy him some fuel lines and a water pump and the other stuff he needs, or the time to put them on for free. I guess if things don't work out it's his problem. I know it isn't going to help the cam lobes any but the motor will be primed again before it is fired. On a good note lots of assembly lube was used so things shouldn't dry up.
08-10-2007, 10:01 PM
#35
Originally Posted by edcmat-l1
So you build a flat tappet motor, and let it sit for a month before firing it.
Hate to be the prophet of doom, but thats like the worst thing you could do. If its at all close to starting, I would spend the few hours its gonna take to get it fired, and at least try to break in the cam. If you let it sit, the longer it sits, the worse its gonna be.
but WTF do I know, I'm just one of those guys thats never built a BBC or had a cam wipe out. Anybody that tells you its not a problem hasnt built many big blocks.
BTW my experience/resume with big blocks goes back over 2 decades.
Hate to be the prophet of doom, but thats like the worst thing you could do. If its at all close to starting, I would spend the few hours its gonna take to get it fired, and at least try to break in the cam. If you let it sit, the longer it sits, the worse its gonna be.
but WTF do I know, I'm just one of those guys thats never built a BBC or had a cam wipe out. Anybody that tells you its not a problem hasnt built many big blocks.
BTW my experience/resume with big blocks goes back over 2 decades.
Don't let the post count here fool you, I've built a couple of engines in the last decade and a half myself. Two decades could be as little as two engines
or maybe one the way some people do things.
Last edited by jakeshoe; 08-10-2007 at 10:06 PM.
08-10-2007, 10:05 PM
#36
Originally Posted by fergymoto
Listen man there's nothing I can do about it. I don't have the extra money to go buy him some fuel lines and a water pump and the other stuff he needs, or the time to put them on for free. I guess if things don't work out it's his problem. I know it isn't going to help the cam lobes any but the motor will be primed again before it is fired. On a good note lots of assembly lube was used so things shouldn't dry up.
Dont take anything I've said personal, it definitely sounds like you did a good job, did the best you could. I just know those motors......
Last edited by edcmat-l1; 08-10-2007 at 10:19 PM.
08-10-2007, 10:17 PM
#37
Jakeshoe, nice certificates. I assume you know what my screen name means? I have been a L1 master tech since the inception of the L1 test.
While that doesnt mean either one of us know his *** from a hole in the ground, you where the one that seemed to not even know the lifter bores in a bbc were canted. Additionally, based on the fact you're unfamiliar with the bbc flat tappet situation, I suggest you keep your certs to yourself and do some more research before posting stuff that makes you look like you're talking out your ***.
See above post, were you said bbc lifter bores were the same as sbc.
And btw, the oiling system from bbc to sbc are not the same either.
The primary galley on a sbc is above the cam. On a bbc its along the pan rail on the drivers side. The aftermarket bbc blocks relocated it to where its postioned in a sbc, above the cam.
Just thought a fellow L1 master tech should know.
While that doesnt mean either one of us know his *** from a hole in the ground, you where the one that seemed to not even know the lifter bores in a bbc were canted. Additionally, based on the fact you're unfamiliar with the bbc flat tappet situation, I suggest you keep your certs to yourself and do some more research before posting stuff that makes you look like you're talking out your ***.
See above post, were you said bbc lifter bores were the same as sbc.
And btw, the oiling system from bbc to sbc are not the same either.
The primary galley on a sbc is above the cam. On a bbc its along the pan rail on the drivers side. The aftermarket bbc blocks relocated it to where its postioned in a sbc, above the cam.
Just thought a fellow L1 master tech should know.
08-10-2007, 10:37 PM
#38
Ed,
The lifter bores are canted, but the cause of lifter failures in a BBC has much more to do with the rocker ratio and modern oils than any angle.
You would have to draw a circle, then draw a line at any angle from the center of the circle, the lifter bores would need to be parallel with the line. Hard to explain online, but the lifter bore issue isn't what the factory design angle is, it is when the bores aren't to blueprint and they cause the lifter to not "sit flat" on the cam.
Having worked in machine shops I understand this, hence the Master machinist cert, Master Auto Tech and L1 doesn't mean squat as far as lifter bore angles or machining a block goes.
The location of the oil galley, which I'm aware of has no effect on the oil actually getting to the same places in the block. It's only a real issue when you are grinding for a stroker motor and don't want to break through. No problem on the later BBC's or SBC, just got to watch the coolant passages.
The BBC oiling system was modeled after the SBC when it was designed.
Almost every domestic V8 since the SBC has modeled it's oiling system very similarly to the SBC. because they work..
The BBC has better oil drainback onto the cam lobes.
The greater rocker ratio and small diameter of the OEM lifter is a weakness of the BBC design, but to say you can't build one with a flat tappet and have it live is not a good argument when GM did it for years and engien remanufacturers still do it daily.
To tell someone, Yeah the BBC is rougher on flat tappets due to the design, and I would highly recommend strictly following break-in/lube procedures, and ALWAYs using a racing oil with high zinc content and/or a zinc additive would be better advice IMO.
Ther eis no doubt that the modern oils are an issue, and it has been covered in depth on many sites.
I've always used diesel oils but it seems they aren't even to par now, and EOS may be discontinued, I'm checking on an alternate PN for that stuff.
I just received a flat tappet cam for a BBC yesterday from my grinder and their invoices now have a notice on them also.
The lifter bores are canted, but the cause of lifter failures in a BBC has much more to do with the rocker ratio and modern oils than any angle.
You would have to draw a circle, then draw a line at any angle from the center of the circle, the lifter bores would need to be parallel with the line. Hard to explain online, but the lifter bore issue isn't what the factory design angle is, it is when the bores aren't to blueprint and they cause the lifter to not "sit flat" on the cam.
Having worked in machine shops I understand this, hence the Master machinist cert, Master Auto Tech and L1 doesn't mean squat as far as lifter bore angles or machining a block goes.
The location of the oil galley, which I'm aware of has no effect on the oil actually getting to the same places in the block. It's only a real issue when you are grinding for a stroker motor and don't want to break through. No problem on the later BBC's or SBC, just got to watch the coolant passages.
The BBC oiling system was modeled after the SBC when it was designed.
Almost every domestic V8 since the SBC has modeled it's oiling system very similarly to the SBC. because they work..
The BBC has better oil drainback onto the cam lobes.
The greater rocker ratio and small diameter of the OEM lifter is a weakness of the BBC design, but to say you can't build one with a flat tappet and have it live is not a good argument when GM did it for years and engien remanufacturers still do it daily.
To tell someone, Yeah the BBC is rougher on flat tappets due to the design, and I would highly recommend strictly following break-in/lube procedures, and ALWAYs using a racing oil with high zinc content and/or a zinc additive would be better advice IMO.
Ther eis no doubt that the modern oils are an issue, and it has been covered in depth on many sites.
I've always used diesel oils but it seems they aren't even to par now, and EOS may be discontinued, I'm checking on an alternate PN for that stuff.
I just received a flat tappet cam for a BBC yesterday from my grinder and their invoices now have a notice on them also.
08-10-2007, 10:58 PM
#39
1st: you come on here posting crap thats wrong, trying to support a theory thats, well, wrong.
2nd: you tout some certs, down talking someone elses experience, touting your own as, well, superior.
3rd: I had about 3 years machine shop experience by about 1987. Theres not much if anything you're gonna tell me that I dont already know.
4th: when confronted with your incorrect posts, you back pedal.
Heres a pic of my shop. Yes, i own it. What do these cars have in common? The smallest motor is 496. what else do they have in common? I either built or tuned or made them run. This was not a photo op. These were real jobs, all in at the same time.
My shop does pretty much nothing but hi perf work, and we have a reputation for making stuff run that no one else can. I am a diagnostic specialist by trade, and have built an entire business on fixing what others cant. Including **** you cant even get wiring diagrams and diagnostic info for.
So, if you want to try and impress, do it elsewhere. Not really impressed by much here. Especially someone whos first few posts were wrong.
Wanna see more? got a long resume....
2nd: you tout some certs, down talking someone elses experience, touting your own as, well, superior.
3rd: I had about 3 years machine shop experience by about 1987. Theres not much if anything you're gonna tell me that I dont already know.
4th: when confronted with your incorrect posts, you back pedal.
Heres a pic of my shop. Yes, i own it. What do these cars have in common? The smallest motor is 496. what else do they have in common? I either built or tuned or made them run. This was not a photo op. These were real jobs, all in at the same time.
My shop does pretty much nothing but hi perf work, and we have a reputation for making stuff run that no one else can. I am a diagnostic specialist by trade, and have built an entire business on fixing what others cant. Including **** you cant even get wiring diagrams and diagnostic info for.
So, if you want to try and impress, do it elsewhere. Not really impressed by much here. Especially someone whos first few posts were wrong.
Wanna see more? got a long resume....
08-10-2007, 11:11 PM
#40
Originally Posted by jakeshoe
Ed,
Having worked in machine shops I understand this, hence the Master machinist cert, Master Auto Tech and L1 doesn't mean squat as far as lifter bore angles or machining a block goes.
Having worked in machine shops I understand this, hence the Master machinist cert, Master Auto Tech and L1 doesn't mean squat as far as lifter bore angles or machining a block goes.
To this day, when I need somethin made, and my buddy with the CNC shop is too busy to get it to me in a day, I just go over and walk in and use his machines, whatever I need.
First you post the lifter bores are the same from SB to BB
Then you post you know they are different
Then you post the oiling systems are the same
Then you post you know they are different.
See where you loose your credibility?