Stupid question:
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Sorry to the OP about drifting off topic from your original question. I believe it has been anwered to your satisfaction and now this has turned into mindless babbling. If you took your 1968 L88 corvette with 10,000 miles in to the chevy dealer to change out the cam do you think they would consider scuffing the bottoms of the original lifters with 600 grit sandpaper and reusing them? How about a 1976 l48 with 100,000?
No way would the dealership even consider reusing them in either case and this is pretty much both ends of the spectrum.
Why? Does their modern service publications say this is acceptable practice?
1. Because best common practice trumps information from 35 years ago.
2. Because they have to warrantee their work and it is cheaper to install new lifters than take even a remote chance that there would be an issue.
3. The cams are different. Ramps, lobe design, spring rates and design, cam core material and hardening techniques, lifter internal design.
4. We have much more information available now, much of it coming from tens if not hundreds of thousands of failed flat tappet cams in the past 10 years.
This is comparable to saying "I have a service manual from my Apple computer I bought in 1999. Can I use it to repair my Ipad"?
The way I see it this is a moot point and there is no arguement. I stand by post # 14 and think refering to a 35 year old publication for validation of what everyone here (including the guy argueing about it) knows is really bad idea is just a good way to try and start a pissing match and has zero basis in logic or sound engineering.
As to the other parts involved. Before changing a cam you should do a compression check. If your tearing it down this far why put it back together with a valve that is not seating properly. Timing gears and chains should be inspected. If it is worn, has noticable slack or the original nylon gear they should be replaced. Geometry should be checked and pushrod ends checked for noticable wear and straightness, Rocker arms and pivot ***** should be checked for wear. I would replace these also especially if using a higher lift cam because the wear pattern will change. The valve tips should be checked for wear and mushrooming, The lifter bores should be checked for excessive clearances. No one is saying the only solution is "go buy a crate engine" just use logic and sound engineering practice when replacing your cam because you want the best chance for long term success for it and your engine.
No way would the dealership even consider reusing them in either case and this is pretty much both ends of the spectrum.
Why? Does their modern service publications say this is acceptable practice?
1. Because best common practice trumps information from 35 years ago.
2. Because they have to warrantee their work and it is cheaper to install new lifters than take even a remote chance that there would be an issue.
3. The cams are different. Ramps, lobe design, spring rates and design, cam core material and hardening techniques, lifter internal design.
4. We have much more information available now, much of it coming from tens if not hundreds of thousands of failed flat tappet cams in the past 10 years.
This is comparable to saying "I have a service manual from my Apple computer I bought in 1999. Can I use it to repair my Ipad"?
The way I see it this is a moot point and there is no arguement. I stand by post # 14 and think refering to a 35 year old publication for validation of what everyone here (including the guy argueing about it) knows is really bad idea is just a good way to try and start a pissing match and has zero basis in logic or sound engineering.
As to the other parts involved. Before changing a cam you should do a compression check. If your tearing it down this far why put it back together with a valve that is not seating properly. Timing gears and chains should be inspected. If it is worn, has noticable slack or the original nylon gear they should be replaced. Geometry should be checked and pushrod ends checked for noticable wear and straightness, Rocker arms and pivot ***** should be checked for wear. I would replace these also especially if using a higher lift cam because the wear pattern will change. The valve tips should be checked for wear and mushrooming, The lifter bores should be checked for excessive clearances. No one is saying the only solution is "go buy a crate engine" just use logic and sound engineering practice when replacing your cam because you want the best chance for long term success for it and your engine.
Last edited by 63mako; Mar 13, 2012 at 11:48 AM.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
I'm not. You asked for a clarification; I posted it. But when I ask who 'they' are that you get your info from, you come up with this cockamamie IBPTBDVMT drivel.
GM, who sells replacement parts, says in their official publications that used lifters...are very satisfactory. But aftermarket cam manufacturers, who make similar parts, say unequivocally, without a doubt, to do so is folly.
So, to summarize: all things that rub up against a camshaft must be new. Except, for some reason, the mechanical fuel pump pushrod. The distributor gear can be old and worn, too. No problem there. And, seemingly, the cam bearings need not be NEW either. What's left, cam gear and chain? Naw, they bolt onto, no rubbing involved. So they need not be new either.
Only those things (used to be called tappets, now known as lifters) that physically touch a cam lobe need always be new. No matter whether high performance grind or low; no matter whether high valve spring pressure or low; no matter whether solid or hydraulic variety; no matter whether it made 10 revolutions or 10 million, once a lifter is removed from its bore, its no longer allowed to be put back into service. Unless, and here's the conundrum, it is mated to the very same cam lobe. But who in their right mind would take that kind of chance if doing so meant a chain detonation of moving valve train parts? Probably best to just buy a crate engine and be done with it.
GM, who sells replacement parts, says in their official publications that used lifters...are very satisfactory. But aftermarket cam manufacturers, who make similar parts, say unequivocally, without a doubt, to do so is folly.
So, to summarize: all things that rub up against a camshaft must be new. Except, for some reason, the mechanical fuel pump pushrod. The distributor gear can be old and worn, too. No problem there. And, seemingly, the cam bearings need not be NEW either. What's left, cam gear and chain? Naw, they bolt onto, no rubbing involved. So they need not be new either. Only those things (used to be called tappets, now known as lifters) that physically touch a cam lobe need always be new. No matter whether high performance grind or low; no matter whether high valve spring pressure or low; no matter whether solid or hydraulic variety; no matter whether it made 10 revolutions or 10 million, once a lifter is removed from its bore, its no longer allowed to be put back into service. Unless, and here's the conundrum, it is mated to the very same cam lobe. But who in their right mind would take that kind of chance if doing so meant a chain detonation of moving valve train parts? Probably best to just buy a crate engine and be done with it.
Keep the shiny side up!
Scott
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Only those things (used to be called tappets, now known as lifters) that physically touch a cam lobe need always be new. No matter whether high performance grind or low; no matter whether high valve spring pressure or low; no matter whether solid or hydraulic variety; no matter whether it made 10 revolutions or 10 million, once a lifter is removed from its bore, its no longer allowed to be put back into service. Unless, and here's the conundrum, it is mated to the very same cam lobe. But who in their right mind would take that kind of chance if doing so meant a chain detonation of moving valve train parts?
with 69 Chevy, Great post and good summary! 
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
I'm not. You asked for a clarification; I posted it. But when I ask who 'they' are that you get your info from, you come up with this cockamamie IBPTBDVMT drivel.
GM, who sells replacement parts, says in their official publications that used lifters...are very satisfactory. But aftermarket cam manufacturers, who make similar parts, say unequivocally, without a doubt, to do so is folly.
So, to summarize: all things that rub up against a camshaft must be new. Except, for some reason, the mechanical fuel pump pushrod. The distributor gear can be old and worn, too. No problem there. And, seemingly, the cam bearings need not be NEW either. What's left, cam gear and chain? Naw, they bolt onto, no rubbing involved. So they need not be new either.
Only those things (used to be called tappets, now known as lifters) that physically touch a cam lobe need always be new. No matter whether high performance grind or low; no matter whether high valve spring pressure or low; no matter whether solid or hydraulic variety; no matter whether it made 10 revolutions or 10 million, once a lifter is removed from its bore, its no longer allowed to be put back into service. Unless, and here's the conundrum, it is mated to the very same cam lobe. But who in their right mind would take that kind of chance if doing so meant a chain detonation of moving valve train parts? Probably best to just buy a crate engine and be done with it.
GM, who sells replacement parts, says in their official publications that used lifters...are very satisfactory. But aftermarket cam manufacturers, who make similar parts, say unequivocally, without a doubt, to do so is folly.
So, to summarize: all things that rub up against a camshaft must be new. Except, for some reason, the mechanical fuel pump pushrod. The distributor gear can be old and worn, too. No problem there. And, seemingly, the cam bearings need not be NEW either. What's left, cam gear and chain? Naw, they bolt onto, no rubbing involved. So they need not be new either. Only those things (used to be called tappets, now known as lifters) that physically touch a cam lobe need always be new. No matter whether high performance grind or low; no matter whether high valve spring pressure or low; no matter whether solid or hydraulic variety; no matter whether it made 10 revolutions or 10 million, once a lifter is removed from its bore, its no longer allowed to be put back into service. Unless, and here's the conundrum, it is mated to the very same cam lobe. But who in their right mind would take that kind of chance if doing so meant a chain detonation of moving valve train parts? Probably best to just buy a crate engine and be done with it.
Personally, I would never re-use a flat tappet lifter, but that's just because I don't feel like I have the experience and know-how to be able to tell if a lifter is re-usable. So, it's safer and easier for someone like me to just get new ones. For someone at my level of knowledge and experience, there are just too many unknown variables, ya know?
Keep the shiny side up!
Scott
