Direct Lube Lifters?
04-18-2018, 08:43 PM
#1
Team Owner
Thread Starter
Member Since: Apr 2008
Location: Coloring within the lines
Posts: 27,345
Received 1,920 Likes
on
1,333 Posts
Direct Lube Lifters?
Call me uninformed and behind the times, but I don't think I had ever heard of these (direct lube lifters).
The question is this:
I'm going to run with a solid old-style lifter cam (most likely an LT1) in my 327, and while pre-shopping came across direct lube lifters. Apparently these have a tiny hole drilled through the face that provides a pressurized oil supply to the lifter/cam interface.
Seems like if done right, this would provide better lubrication assurance than splash lubrication for the lifter/cam interface.
School me, please.
The question is this:
I'm going to run with a solid old-style lifter cam (most likely an LT1) in my 327, and while pre-shopping came across direct lube lifters. Apparently these have a tiny hole drilled through the face that provides a pressurized oil supply to the lifter/cam interface.
Seems like if done right, this would provide better lubrication assurance than splash lubrication for the lifter/cam interface.
School me, please.
04-18-2018, 08:56 PM
#2
Race Director
You might be right......................but
There are probably 50 million older cars on the road with conventional lifters and many millions before that that have run reliability with the current hydraulic/solid lifter and cam design. I am in this category with having owned over a dozen such cars and not had issues.
If it ain't broke.............
I would like to see the company testing results compared to the "standard design" and see how they are better.
FWIW.........maybe nothing.
Larry
EDIT: It appears that Howards Cams is the source of these, correct. https://www.summitracing.com/parts/hrs-91118 The hydraulic lifters use a slight flat in the lifter barrel to accomplish the same lifter/cam lubrication. I would still like to see test results comparison. I guess if I was having repeated trouble with my cam and lifters failing and did not want to run rollers, I might be tempted to try. But for many of us with stock valve trains and factory cams that run well, why change??
Now I do like the "anti-pump-up" lifters for cars with hydraulic cams that run at elevated RPMs. I used these back in the day and they did help some.
There are probably 50 million older cars on the road with conventional lifters and many millions before that that have run reliability with the current hydraulic/solid lifter and cam design. I am in this category with having owned over a dozen such cars and not had issues.
If it ain't broke.............
I would like to see the company testing results compared to the "standard design" and see how they are better.
FWIW.........maybe nothing.
Larry
EDIT: It appears that Howards Cams is the source of these, correct. https://www.summitracing.com/parts/hrs-91118 The hydraulic lifters use a slight flat in the lifter barrel to accomplish the same lifter/cam lubrication. I would still like to see test results comparison. I guess if I was having repeated trouble with my cam and lifters failing and did not want to run rollers, I might be tempted to try. But for many of us with stock valve trains and factory cams that run well, why change??
Now I do like the "anti-pump-up" lifters for cars with hydraulic cams that run at elevated RPMs. I used these back in the day and they did help some.
Last edited by Powershift; 04-18-2018 at 09:18 PM.
04-18-2018, 09:31 PM
#3
Safety Car
Member Since: Jan 2000
Location: Poway CA
Posts: 4,845
Received 1,295 Likes
on
560 Posts
2023 C1 of the Year Finalist - Unmodified
2022 C1 of the Year Finalist - Unmodified
2021 C1 of the Year Finalist - Unmodified
2019 C1 of Year Finalist (stock)
2016 C1 of Year Finalist
The LT-1 used 'edge orifice lifters'
One of the features of edge orifice lifters is that they flow LESS oil to the push rod. The concern in the LT-1 was that too much oil would be on the top of the motor at high RPM, letting the pan starve.
EDIT: The LT-1 also had a high volume oil pump..
One of the features of edge orifice lifters is that they flow LESS oil to the push rod. The concern in the LT-1 was that too much oil would be on the top of the motor at high RPM, letting the pan starve.
EDIT: The LT-1 also had a high volume oil pump..
Last edited by SDVette; 04-19-2018 at 11:57 AM.
04-18-2018, 09:57 PM
#4
Team Owner
Actually direct lube of the lifters I have done to my Small Block engine that turns 8200rpms, and that is drilling to the block to spray at the lifter foot to cam lobe face direct. But then some of the lifter manufacturers now call some of their hydraulic units by this name (direct lube) and I think they are drilling a hole in the foot.
I think one of the Smokey Yunick articles covers the old block race modification method. I have seen some articles on the new way of doing it all with the lifter, but haven't read!
What is happening is a constant pressured spray to the cam and lifter, that is just not reliant on splash.
The solids have two holes in two differing locations! The normal volume units have the hole in the void of the body, and the edge orifice ones in the side to limit oil to the upper for when you run like roller rockers. I still at higher rpm capable engines like the rocker dripper valve covers to drip oil down for the sake of the valve springs and retainers, and not just what gets sent up the push rod. For a while I had some real special hole drilled valve springs retainers (Scalloped ICD style Manley units) that allowed oil to drip thru to the springs direct, but those were experiencing deformation and heading toward failure (lucky they were titanium). PS I don't like titanium either, but it is cheaper. I run Inconel Exhaust valves now, and get by with the necked down stainless ones on the intake (cooler side).
Not many turn their street engines to 8200 rpms. Until you turn lets say 6800, I won't worry about any of this fancy stuff.
I think one of the Smokey Yunick articles covers the old block race modification method. I have seen some articles on the new way of doing it all with the lifter, but haven't read!
What is happening is a constant pressured spray to the cam and lifter, that is just not reliant on splash.
The solids have two holes in two differing locations! The normal volume units have the hole in the void of the body, and the edge orifice ones in the side to limit oil to the upper for when you run like roller rockers. I still at higher rpm capable engines like the rocker dripper valve covers to drip oil down for the sake of the valve springs and retainers, and not just what gets sent up the push rod. For a while I had some real special hole drilled valve springs retainers (Scalloped ICD style Manley units) that allowed oil to drip thru to the springs direct, but those were experiencing deformation and heading toward failure (lucky they were titanium). PS I don't like titanium either, but it is cheaper. I run Inconel Exhaust valves now, and get by with the necked down stainless ones on the intake (cooler side).
Not many turn their street engines to 8200 rpms. Until you turn lets say 6800, I won't worry about any of this fancy stuff.
Last edited by TCracingCA; 04-19-2018 at 01:12 PM.
04-19-2018, 12:43 AM
#5
Le Mans Master
GM had a lifter with an oiling slot on the side of the lifter. I think they were standard on the 2.8L GM V6, early 90's I think. I knew some racers that used them to replace the 817 lifter. I have never seen the direct drill or oiling hole in a lifter but I have been mostly out of that business for 10 years now.
04-19-2018, 01:49 AM
#6
Team Owner
I just wonder because of cheap Chinese steel, if these came into being based on failures!
04-19-2018, 01:50 AM
#7
Team Owner
GM had a lifter with an oiling slot on the side of the lifter. I think they were standard on the 2.8L GM V6, early 90's I think. I knew some racers that used them to replace the 817 lifter. I have never seen the direct drill or oiling hole in a lifter but I have been mostly out of that business for 10 years now.
Last edited by TCracingCA; 04-19-2018 at 01:51 AM.
04-19-2018, 08:56 AM
#8
Team Owner
Thread Starter
Member Since: Apr 2008
Location: Coloring within the lines
Posts: 27,345
Received 1,920 Likes
on
1,333 Posts
You all make great points, thanks.
While I recognize that avoiding junk parts is the first priority, given the problem with ZDDP in oil problems, I’ll probably try to find some good direct lube lifters.
While I recognize that avoiding junk parts is the first priority, given the problem with ZDDP in oil problems, I’ll probably try to find some good direct lube lifters.
04-19-2018, 09:47 AM
#9
Drifting
Member Since: Apr 2014
Location: montague michigan
Posts: 1,744
Received 77 Likes
on
61 Posts
C2 of Year Finalist (stock) 2019
Call me uninformed and behind the times, but I don't think I had ever heard of these (direct lube lifters).
The question is this:
I'm going to run with a solid old-style lifter cam (most likely an LT1) in my 327, and while pre-shopping came across direct lube lifters. Apparently these have a tiny hole drilled through the face that provides a pressurized oil supply to the lifter/cam interface.
Seems like if done right, this would provide better lubrication assurance than splash lubrication for the lifter/cam interface.
School me, please.
The question is this:
I'm going to run with a solid old-style lifter cam (most likely an LT1) in my 327, and while pre-shopping came across direct lube lifters. Apparently these have a tiny hole drilled through the face that provides a pressurized oil supply to the lifter/cam interface.
Seems like if done right, this would provide better lubrication assurance than splash lubrication for the lifter/cam interface.
School me, please.
easy rhino,let me explain how and why i use these lifter.
i was a heavy class drag racer for alot of years. belonging too NHRA and NMCA. finishing in the top ten in points in the country. i worked at one of the biggest engine builders of the FASTEST STREET CARS in the country. the class we ran required the use of stock appearing parts in the beginning, and eventually we were allowed too use a little more exotic stuff, performance lifters, springs and rockers..any way, we started using the "EDM" lifters as we called them because of the big spring pressures we had too run too make the power. the EDM hole allowed a film of oil too be pressurized against the cam lobe too keep the metal too metal contact down.which allowed bigger psi springs. we then started installing them in our solid lifter motors for street use with great results. no premature failures of cam lobes any more. i have personally used these in all my restorations of factory HP motors. including my crossram 302 8500 rpm 69 Z28, my l78 65 corvette, and several other 302 chevys i have built over the years along with several big horse 327, 350, 396, 427 motors. and none of them had one lifter or cam lobe failure!
so the old saying of "if it aint broke dont fix it" is way off with this. this is a definite PLUS in my book for durability and piece of mind. this of course is my humble opinion...troy
The following 4 users liked this post by 20round:
04-19-2018, 10:14 AM
#10
Race Director
easy rhino,let me explain how and why i use these lifter.
i was a heavy class drag racer for alot of years. belonging too NHRA and NMCA. finishing in the top ten in points in the country. i worked at one of the biggest engine builders of the FASTEST STREET CARS in the country. the class we ran required the use of stock appearing parts in the beginning, and eventually we were allowed too use a little more exotic stuff, performance lifters, springs and rockers..any way, we started using the "EDM" lifters as we called them because of the big spring pressures we had too run too make the power. the EDM hole allowed a film of oil too be pressurized against the cam lobe too keep the metal too metal contact down.which allowed bigger psi springs. we then started installing them in our solid lifter motors for street use with great results. no premature failures of cam lobes any more. i have personally used these in all my restorations of factory HP motors. including my crossram 302 8500 rpm 69 Z28, my l78 65 corvette, and several other 302 chevys i have built over the years along with several big horse 327, 350, 396, 427 motors. and none of them had one lifter or cam lobe failure!
so the old saying of "if it aint broke dont fix it" is way off with this. this is a definite PLUS in my book for durability and piece of mind. this of course is my humble opinion...troy
i was a heavy class drag racer for alot of years. belonging too NHRA and NMCA. finishing in the top ten in points in the country. i worked at one of the biggest engine builders of the FASTEST STREET CARS in the country. the class we ran required the use of stock appearing parts in the beginning, and eventually we were allowed too use a little more exotic stuff, performance lifters, springs and rockers..any way, we started using the "EDM" lifters as we called them because of the big spring pressures we had too run too make the power. the EDM hole allowed a film of oil too be pressurized against the cam lobe too keep the metal too metal contact down.which allowed bigger psi springs. we then started installing them in our solid lifter motors for street use with great results. no premature failures of cam lobes any more. i have personally used these in all my restorations of factory HP motors. including my crossram 302 8500 rpm 69 Z28, my l78 65 corvette, and several other 302 chevys i have built over the years along with several big horse 327, 350, 396, 427 motors. and none of them had one lifter or cam lobe failure!
so the old saying of "if it aint broke dont fix it" is way off with this. this is a definite PLUS in my book for durability and piece of mind. this of course is my humble opinion...troy
Larry
04-19-2018, 10:16 AM
#11
Melting Slicks
easy rhino,let me explain how and why i use these lifter.
i was a heavy class drag racer for alot of years. belonging too NHRA and NMCA. finishing in the top ten in points in the country. i worked at one of the biggest engine builders of the FASTEST STREET CARS in the country. the class we ran required the use of stock appearing parts in the beginning, and eventually we were allowed too use a little more exotic stuff, performance lifters, springs and rockers..any way, we started using the "EDM" lifters as we called them because of the big spring pressures we had too run too make the power. the EDM hole allowed a film of oil too be pressurized against the cam lobe too keep the metal too metal contact down.which allowed bigger psi springs. we then started installing them in our solid lifter motors for street use with great results. no premature failures of cam lobes any more. i have personally used these in all my restorations of factory HP motors. including my crossram 302 8500 rpm 69 Z28, my l78 65 corvette, and several other 302 chevys i have built over the years along with several big horse 327, 350, 396, 427 motors. and none of them had one lifter or cam lobe failure!
so the old saying of "if it aint broke dont fix it" is way off with this. this is a definite PLUS in my book for durability and piece of mind. this of course is my humble opinion...troy
i was a heavy class drag racer for alot of years. belonging too NHRA and NMCA. finishing in the top ten in points in the country. i worked at one of the biggest engine builders of the FASTEST STREET CARS in the country. the class we ran required the use of stock appearing parts in the beginning, and eventually we were allowed too use a little more exotic stuff, performance lifters, springs and rockers..any way, we started using the "EDM" lifters as we called them because of the big spring pressures we had too run too make the power. the EDM hole allowed a film of oil too be pressurized against the cam lobe too keep the metal too metal contact down.which allowed bigger psi springs. we then started installing them in our solid lifter motors for street use with great results. no premature failures of cam lobes any more. i have personally used these in all my restorations of factory HP motors. including my crossram 302 8500 rpm 69 Z28, my l78 65 corvette, and several other 302 chevys i have built over the years along with several big horse 327, 350, 396, 427 motors. and none of them had one lifter or cam lobe failure!
so the old saying of "if it aint broke dont fix it" is way off with this. this is a definite PLUS in my book for durability and piece of mind. this of course is my humble opinion...troy
04-19-2018, 11:23 AM
#12
Race Director
Member Since: May 2000
Location: Redondo Beach USA
Posts: 12,487
Received 1,974 Likes
on
1,188 Posts
The small block valve train is very reliable (other than lobe wear on some later C3 era cams due to process changes that reduced durability).
With proper OE equivalent valve spring setup, the LT-l cam valve train limiting speed is about 7200, but the engine won't make usable power this high unless the OE heads are massaged or it has better than OE flowing aftermarket heads.
It's your engine, but why experiment with something that works?
Duke
The following users liked this post:
Easy Rhino (07-15-2018)
04-19-2018, 11:59 AM
#13
Safety Car
https://www.speedwaymotors.com/COMP-...Hole,9234.html
The following users liked this post:
Easy Rhino (04-19-2018)
04-19-2018, 08:04 PM
#14
Drifting
Member Since: Apr 2014
Location: montague michigan
Posts: 1,744
Received 77 Likes
on
61 Posts
C2 of Year Finalist (stock) 2019
These lifters are well worth the money. Used em consistently in big blocks for the last 15 years. You still need to use engine oil with ZDDP additive.
https://www.speedwaymotors.com/COMP-...Hole,9234.html
https://www.speedwaymotors.com/COMP-...Hole,9234.html
with the ZDDP oil. i for got too mention that in my original post here. we use nothing but brad penn oils in all our engines..troy
04-20-2018, 01:29 PM
#15
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
Posts: 7,098
Received 373 Likes
on
356 Posts
Well that's a fairly new innovation to lifters and I need to keep an open mind until I can be convinced. But isn't a solid flat tappet at an advantage over a hydraulic lifter? I'm referring to the lash adjustment which in turn allows the lifter to slap the lobe a little bit each cycle/revolution until the engine warms and then some. I would expect this would induce some amount of lifter rotation. Smokey Yunick (RIP) described flat tappet break-in procedures using lighter valve springs but didn't mention any difference between solid or hydraulic lifters for this.
Anyone found there is an advantage to breaking in solid lifters?
Anyone found there is an advantage to breaking in solid lifters?
04-21-2018, 02:21 AM
#16
Team Owner
Member Since: Nov 2005
Location: Beach & High Desert Southern California
Posts: 25,501
Received 2,346 Likes
on
891 Posts
Well that's a fairly new innovation to lifters and I need to keep an open mind until I can be convinced. But isn't a solid flat tappet at an advantage over a hydraulic lifter? I'm referring to the lash adjustment which in turn allows the lifter to slap the lobe a little bit each cycle/revolution until the engine warms and then some. I would expect this would induce some amount of lifter rotation. Smokey Yunick (RIP) described flat tappet break-in procedures using lighter valve springs but didn't mention any difference between solid or hydraulic lifters for this.
Anyone found there is an advantage to breaking in solid lifters?
Anyone found there is an advantage to breaking in solid lifters?
The interface misalignment between the cam and lifter that promotes the lifter to spin is ground into the cam lobe. The cam lobe for a round flat tappet is slightly crowned with the high point off center to promote the lifter spin. The new lifter face is perfectly flat. The lifter spin is from unequal friction from the cam lobe crown across the lifter face. The spin promotes a sliding face contact that collects and squeezes the oil film ahead of the contact interface, resulting in a sliding friction coefficient that is close to the friction of a rolling face contact. The physics of the face oil film movement is also why the oil hole is off center in the lifter face, to locate the oil where the closest contact occurs.
This offset cam lobe crown is why well used lifters have a noticeable concave face, from the wear point of the lobe crown contact. It is also why used lifters should only be reused on the same cam lobe. A mismatch of the new lobe and used lifter concave wear can prevent the lifter spin, and flatten the new cam lobe.
A new flat lifter face endures break in from the off center crowned lobe of a used cam just like with a new cam, and spins. The risk of prior lifter wear altering the used cam lobe crown is low, but something to consider during an engine rebuild.
The cam lobe for a roller lifter or fixed cam follower does not need the crown, because there is no need to spin the lifter, and the cam lobe is ground square for full roller or follower width contact. The full width contact area reduces surface fatigue on the lifter and cam, enhancing the service life of a roller lifter assembly, even with higher rate valve springs and quicker lift acceleration rates compared to a round lifter.
If you use a roller cam with flat lifters, the lifters do not spin, and the lobes wear quickly (faster than the cam material difference contribution alone).
Its not the lash adjustment that promotes the lifter to spin, so there is no wear rate advantage to a lashed solid lifter over the continuous sliding face contact of a spinning hydraulic lifter. In fact, the solid lifter face wear is greater from surface fatigue induced by the impact as the lash is consumed, and why people concerned about valve train wear and noise are obsessed with setting lash at the clearance ramps of the lobe design (even if the lash does not make the best power for the engine assembly).
.
The following users liked this post:
tuxnharley (04-22-2018)
04-21-2018, 11:28 AM
#17
Race Director
Member Since: May 2000
Location: Redondo Beach USA
Posts: 12,487
Received 1,974 Likes
on
1,188 Posts
In fact, the solid lifter face wear is greater from surface fatigue induced by the impact as the lash is consumed, and why people concerned about valve train wear and noise are obsessed with setting lash at the clearance ramps of the lobe design (even if the lash does not make the best power for the engine assembly).
Valve train noise is all those little "hammers" (lobes) whacking all those little "anvils" (lifters) at greater than clearance ramp velocity. If the clearance is set to take up lash at no more than clearance ramp velocity it may even be tough to tell that the cam is mechanical rather than hydraulic lifter.
Duke
Last edited by SWCDuke; 04-21-2018 at 11:35 AM.
04-21-2018, 01:13 PM
#18
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
Posts: 7,098
Received 373 Likes
on
356 Posts
I think I should have emphasized in my post (#15) a solid lifter would have an advantage for lifter break-in.. I can see now how my post could read like I was talking about lobe or cam life. I really was asking about an advantage for lifter break-in when starting lifter rotation is crucial.
I tend to look at solid lifter having to move with respect to the lobe each cam rotation whether it wants to or not. More of cheap substitute for a roller cam for those of us that want to avoid wiping cam lobes on breaking in a new cam. Well somewhat cheaper as solid lifters are not as cheap as hydraulic lifters - at least when I last shopped for solid lifters.
I tend to look at solid lifter having to move with respect to the lobe each cam rotation whether it wants to or not. More of cheap substitute for a roller cam for those of us that want to avoid wiping cam lobes on breaking in a new cam. Well somewhat cheaper as solid lifters are not as cheap as hydraulic lifters - at least when I last shopped for solid lifters.
04-21-2018, 05:42 PM
#19
Team Owner
Member Since: Jan 2007
Location: Southern Cal Ca
Posts: 50,467
Received 762 Likes
on
613 Posts
St. Jude Donor '22
The lifters with the electric discharge oil hole have been around since before the oil additive change, and they work as designed. The lifter face oil hole is off center as part of the design. They result in benefits to reduce wear and noise.
The interface misalignment between the cam and lifter that promotes the lifter to spin is ground into the cam lobe. The cam lobe for a round flat tappet is slightly crowned with the high point off center to promote the lifter spin. The new lifter face is perfectly flat. The lifter spin is from unequal friction from the cam lobe crown across the lifter face. The spin promotes a sliding face contact that collects and squeezes the oil film ahead of the contact interface, resulting in a sliding friction coefficient that is close to the friction of a rolling face contact. The physics of the face oil film movement is also why the oil hole is off center in the lifter face, to locate the oil where the closest contact occurs.
This offset cam lobe crown is why well used lifters have a noticeable concave face, from the wear point of the lobe crown contact. It is also why used lifters should only be reused on the same cam lobe. A mismatch of the new lobe and used lifter concave wear can prevent the lifter spin, and flatten the new cam lobe.
A new flat lifter face endures break in from the off center crowned lobe of a used cam just like with a new cam, and spins. The risk of prior lifter wear altering the used cam lobe crown is low, but something to consider during an engine rebuild.
The cam lobe for a roller lifter or fixed cam follower does not need the crown, because there is no need to spin the lifter, and the cam lobe is ground square for full roller or follower width contact. The full width contact area reduces surface fatigue on the lifter and cam, enhancing the service life of a roller lifter assembly, even with higher rate valve springs and quicker lift acceleration rates compared to a round lifter.
If you use a roller cam with flat lifters, the lifters do not spin, and the lobes wear quickly (faster than the cam material difference contribution alone).
Its not the lash adjustment that promotes the lifter to spin, so there is no wear rate advantage to a lashed solid lifter over the continuous sliding face contact of a spinning hydraulic lifter. In fact, the solid lifter face wear is greater from surface fatigue induced by the impact as the lash is consumed, and why people concerned about valve train wear and noise are obsessed with setting lash at the clearance ramps of the lobe design (even if the lash does not make the best power for the engine assembly).
.
The interface misalignment between the cam and lifter that promotes the lifter to spin is ground into the cam lobe. The cam lobe for a round flat tappet is slightly crowned with the high point off center to promote the lifter spin. The new lifter face is perfectly flat. The lifter spin is from unequal friction from the cam lobe crown across the lifter face. The spin promotes a sliding face contact that collects and squeezes the oil film ahead of the contact interface, resulting in a sliding friction coefficient that is close to the friction of a rolling face contact. The physics of the face oil film movement is also why the oil hole is off center in the lifter face, to locate the oil where the closest contact occurs.
This offset cam lobe crown is why well used lifters have a noticeable concave face, from the wear point of the lobe crown contact. It is also why used lifters should only be reused on the same cam lobe. A mismatch of the new lobe and used lifter concave wear can prevent the lifter spin, and flatten the new cam lobe.
A new flat lifter face endures break in from the off center crowned lobe of a used cam just like with a new cam, and spins. The risk of prior lifter wear altering the used cam lobe crown is low, but something to consider during an engine rebuild.
The cam lobe for a roller lifter or fixed cam follower does not need the crown, because there is no need to spin the lifter, and the cam lobe is ground square for full roller or follower width contact. The full width contact area reduces surface fatigue on the lifter and cam, enhancing the service life of a roller lifter assembly, even with higher rate valve springs and quicker lift acceleration rates compared to a round lifter.
If you use a roller cam with flat lifters, the lifters do not spin, and the lobes wear quickly (faster than the cam material difference contribution alone).
Its not the lash adjustment that promotes the lifter to spin, so there is no wear rate advantage to a lashed solid lifter over the continuous sliding face contact of a spinning hydraulic lifter. In fact, the solid lifter face wear is greater from surface fatigue induced by the impact as the lash is consumed, and why people concerned about valve train wear and noise are obsessed with setting lash at the clearance ramps of the lobe design (even if the lash does not make the best power for the engine assembly).
.
04-21-2018, 06:30 PM
#20
The lifters with the electric discharge oil hole have been around since before the oil additive change, and they work as designed. The lifter face oil hole is off center as part of the design. They result in benefits to reduce wear and noise.
The interface misalignment between the cam and lifter that promotes the lifter to spin is ground into the cam lobe. The cam lobe for a round flat tappet is slightly crowned with the high point off center to promote the lifter spin. The new lifter face is perfectly flat. The lifter spin is from unequal friction from the cam lobe crown across the lifter face. The spin promotes a sliding face contact that collects and squeezes the oil film ahead of the contact interface, resulting in a sliding friction coefficient that is close to the friction of a rolling face contact. The physics of the face oil film movement is also why the oil hole is off center in the lifter face, to locate the oil where the closest contact occurs.
This offset cam lobe crown is why well used lifters have a noticeable concave face, from the wear point of the lobe crown contact. It is also why used lifters should only be reused on the same cam lobe. A mismatch of the new lobe and used lifter concave wear can prevent the lifter spin, and flatten the new cam lobe.
A new flat lifter face endures break in from the off center crowned lobe of a used cam just like with a new cam, and spins. The risk of prior lifter wear altering the used cam lobe crown is low, but something to consider during an engine rebuild.
The cam lobe for a roller lifter or fixed cam follower does not need the crown, because there is no need to spin the lifter, and the cam lobe is ground square for full roller or follower width contact. The full width contact area reduces surface fatigue on the lifter and cam, enhancing the service life of a roller lifter assembly, even with higher rate valve springs and quicker lift acceleration rates compared to a round lifter.
If you use a roller cam with flat lifters, the lifters do not spin, and the lobes wear quickly (faster than the cam material difference contribution alone).
Its not the lash adjustment that promotes the lifter to spin, so there is no wear rate advantage to a lashed solid lifter over the continuous sliding face contact of a spinning hydraulic lifter. In fact, the solid lifter face wear is greater from surface fatigue induced by the impact as the lash is consumed, and why people concerned about valve train wear and noise are obsessed with setting lash at the clearance ramps of the lobe design (even if the lash does not make the best power for the engine assembly).
.
The interface misalignment between the cam and lifter that promotes the lifter to spin is ground into the cam lobe. The cam lobe for a round flat tappet is slightly crowned with the high point off center to promote the lifter spin. The new lifter face is perfectly flat. The lifter spin is from unequal friction from the cam lobe crown across the lifter face. The spin promotes a sliding face contact that collects and squeezes the oil film ahead of the contact interface, resulting in a sliding friction coefficient that is close to the friction of a rolling face contact. The physics of the face oil film movement is also why the oil hole is off center in the lifter face, to locate the oil where the closest contact occurs.
This offset cam lobe crown is why well used lifters have a noticeable concave face, from the wear point of the lobe crown contact. It is also why used lifters should only be reused on the same cam lobe. A mismatch of the new lobe and used lifter concave wear can prevent the lifter spin, and flatten the new cam lobe.
A new flat lifter face endures break in from the off center crowned lobe of a used cam just like with a new cam, and spins. The risk of prior lifter wear altering the used cam lobe crown is low, but something to consider during an engine rebuild.
The cam lobe for a roller lifter or fixed cam follower does not need the crown, because there is no need to spin the lifter, and the cam lobe is ground square for full roller or follower width contact. The full width contact area reduces surface fatigue on the lifter and cam, enhancing the service life of a roller lifter assembly, even with higher rate valve springs and quicker lift acceleration rates compared to a round lifter.
If you use a roller cam with flat lifters, the lifters do not spin, and the lobes wear quickly (faster than the cam material difference contribution alone).
Its not the lash adjustment that promotes the lifter to spin, so there is no wear rate advantage to a lashed solid lifter over the continuous sliding face contact of a spinning hydraulic lifter. In fact, the solid lifter face wear is greater from surface fatigue induced by the impact as the lash is consumed, and why people concerned about valve train wear and noise are obsessed with setting lash at the clearance ramps of the lobe design (even if the lash does not make the best power for the engine assembly).
.