My Javelin developed noisy tappets after 7k miles. Inspection showed some of the tappets had ceased spinning and showed heavy patterns of a straight swipe across the bottom. As a precaution, a second motor with close to the same mileage was inspected and had two tappets just beginning to fail.
The tappet at the left shows it was rotating; the other two have failed to rotate and show wear across the bottom.
Pretty certain the cams were properly broken in and that high zinc oils were always used, so the failures could be caused by several issues. Did the cam wear down or did the tappet fail? Did the bore in the case somehow stop rotation?
First thing was to check how the cam lobes aligned with the tappets. An old tappet was ground to a point.
It was placed in each tappet bore and the camshaft turned, pressing the cam against the face of the case.
The trace can be seen on each lobe as a fine line offset to one side of the lobe.
Note that the scribe lines are on opposite sides of the lobes in sort of a mirror image. This means that the tappets rotate in opposite directions.
Easier to see in this picture.
Note that the amount of offset varies greatly.
Camshaft and tappet failures
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Camshaft and tappet failures
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Keith Clements
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Re: Camshaft and tappet failures
Well that answers one of the questions we had from our extensive email exchange.
It is unlikely the shape of the cam lobe or the curvature of the follower would affect the force encouraging the tappet to rotate.
I suspect the cause is oil feed or muck in the follower cylinder. As I said I have noticed many tight followers.
It could possibly be the push rod stopping the rotation as sometimes there is so much stiction in the balls on the ends that turning is difficult. The tappets too could close up and prevent rotation. So does rotation only occur when there is a tappet gap and valves are closed?
It is unlikely the shape of the cam lobe or the curvature of the follower would affect the force encouraging the tappet to rotate.
I suspect the cause is oil feed or muck in the follower cylinder. As I said I have noticed many tight followers.
It could possibly be the push rod stopping the rotation as sometimes there is so much stiction in the balls on the ends that turning is difficult. The tappets too could close up and prevent rotation. So does rotation only occur when there is a tappet gap and valves are closed?
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OIL
https://www.rlengines.com/Web_Pages/Tech.html
Has some good articles so I have saved this edited one here just in case it goes walkies from that site.
You may also like this light hearted one on WD40
https://www.rlengines.com/Web_Pages/WD40.html
Or this one on engine balancing.
https://www.rlengines.com/Web_Pages/Cra ... ncing.html
From which I remember this.
https://www.rlengines.com/Web_Pages/pistonrings.html
BY DAVE HAGEN, MIKE CARUSO,and STEVE FOX
AERA is providing you with this information just in case you have not heard about problems with flat tappet
camshaft failures caused by gasoline engine oils. The problem started years ago when oi l companies reduced the anri-scuffing additive packages in gasoline engine oils. When reduced, we all started to have flat tappet camshaft and lifter failures.
Everyone was quick to blame camshaft or lifter hardness, however that was not the case at all.
Flat tappet camshaft and lifter failures have increased over the last ten years and it has been real ly bad for the last three years. As AERA
members reported flat rapper camshaft and lifter failures, we kept track of them and discovered two issues to be common denominators:
· 75% of the failures were, in part, due to a reduction of anti-scuffing additive packages in the gasoline engine oils;
• The other 25% of failures were caused by improper break-in procedures such as not pre-oiling the engine before start-up and letting the
engine idle.
Although 75% failed when using late model engine oil for break-in, looking back, these failures coincided with EPA mandared for reduction
of Zinc additive over the past ten years in gasoline engine oils for cleaner air and longer life of the catalytic converters.
Remember, we aII have to breathe the same air. This is no problem in late model engines using roller lifters and camshafts because they do not need the anti-scuffing additive packages ro procect the sliding anion of flat rapper camshaft and lifter surfaces.
Special Note - During engine disassembly, check camshaft side of lifter bore hole (or wear (egg-shaping) of the lifter bore hole in the block.
If it has worn egg-shaped, fix it by bushing the lifter bore or replace block. This eggshaping will allow the lifter foot or bottom which contacts the camshaft lobe to move off center line, changing the lifter to lobe contact angle. Now, the lifter acts as a scraper removing the oil film between it and the cam lobe causing metal to metal contact and cam and lifter failure.
The API Service Symbol
The API service symbol "donut" is divided into three parts. The top half describes rhe oil's performance level.
The center identifies the oil's viscosity. The bottom half tells whether the oil has demonstra#ted energy conserving properties in a standard test in comparison to a reference oil.
Performance levels:
The top of the donut shows the oil's performance level for gasoline and/or diesel engines.
The letter" S" followed by another letter (for example, SM) refers to oil suitable for gasoline engines. The letter "C" fo llowed by another
letter and/or number (for example, CI-4) refers to oil suitable for diesel engines.
These letters officially stand for "Service" and "Commercial." The current API performance categories that can appear in the top part of the Donut are listed in the API Motor Oil Guide.
SAE Viscosity Grade
The center of the Donut shows the oil's SAE viscosity grade. Viscosity is a measure of oil's flow characteristics, or thickness, at certain temperatures.
The low-temperature viscosity (the first number, 5W in 5W-30 oil) indicates how quickly an engine will crank in winter and how well the oil
will flow to lubricate critical engine parts at low temperatures. The lower the number the more easily the engine will start in cold weather.
The high-temperature viscosity (the second number, 30 in a 5W-30 oil) provides thickness, or body, for good lubrication at operating tempenltures.
Multi-grade oil (for example, SAE 5W-30) provides good flow capability for cold weather but still retains thickness for high temperature
lubrication .
Single grade oil (a single number in the center of the donut) is recommended for use under a much narrower set of temperature conditions
than multi-grade oils.
Operators should refer to their owner's manuals to select the proper viscosity oil for the ambient temperature and operating conditions at
which the equipment will be used.
Off-Road Oils
Straight weight racing oils these applications contain higher concentrations of anti' wear agents such as in the Castrol GP series or the Pennzoil with Z-7. If you're not sure whether your oil has the proper anti-wear agents all you have to do is smell it. If it has an aroma that faintly resembles gear oil then it probably has a higher concentration of wear inhibitors.
It is important to choose a viscosity range that will work with your older, high compression engine and its
bigger clearances. Forget the OW-30 and 5W-20 used in today's engines, today's engines run tight
clearances ... they are specifically designed to work with these new, thinner oils.
Older engines used heavier weight oils designed for the time you used straight 10 or 20 for winter, 30, 40 weights for summer. Then the 10W-30, 10W-40, 20W-40 and 20W-50 came along andworked fine. 1f you're runninga flat tappet mechanical camshaft today in 2008, you
have a big problem because you are limited on which oils to use. Most of oils do not have the shear strength or the anti-scuffing additive packages necessary to keep these camshaft and lifters properly lu bricated. If you use late type motor oil in your engine with a mechanical flat tappet camshaft you possibly could experience premature camshaft failure! Mechanical camshaft engines require oils containing higher
concentrations of anti-wear additives phosphorous and zinc (1200-1300ppm VS less than 1000 for conventional oils). See AERA TB 2333R.
Why oil pressure is low at a hot idle after rebuilding
This is a good time to mention measuring engine oil clearance when rebuilding a late model engines. AERA receives calls asking why the
oil pressure is too low after a late model or any engine is rebuilt.
AERA Tech Support will first ask, "What is the measured oil clearance on the engine bearings mains, rods, camshaft and balance shaft?"
The answer will be, "Well it's a .010-.010 crank and bearings."
In other words, they never measured it. So, it's no wonder they have problems with having low oil pressure at a hot idle!
Engine oil systems are a leak system by design. Knowing this fact, an engine with hot oil of 167-195°F has (within specifications) idle oil
pressure because of tight clearances.
But as an engine falls below the specification the idle oil pressure is lowered.
Don't be fooled by measuring the crankshaft and then trying to use the listed size in the catalog bearing shell thickness. Measure,
measure, mehttps://jowett.net/services/account/activation/ac6df27aed3b0fa7625a3a96a91f3c17asure!
Break-in Lubes
Use liberal amounts of any brand when installing new camshaft and lifters.
In terms of oil selection, we recommend Shell Rotella T oil for the break-in procedure.
Spring Pressures
Normal recommended springm seat pressure for most mild street-type Aat tappet cams is between 85 to 105 lbs. More radical street and race applications may use valve spring seat pressure between 105 to 130 lbs.
Spring Coil Bind
This is when all of the coils of the spring (outside, inside or flat damper) contact each other before the full lift of the valve. We recommend that the spring you are using becapable of traveling at least .060" more than the valve lift of the cam from its assembled
height.
Retainer to Seal Valve or Guide Boss Interference
You need a t least .060" clearance between the bottom of the retainer and the seal or the top of rhe valve guide when the valve is at full lift.
Valve to Piston Interference:
Increased va lve lift, valve thickness and diameter, (check valve to valve relief diameter in pistons), re-surfacing the block andlor cylinder head(s) will reduce PN clearance.
Minimum PN clearance +.080" intake and +. 100" exhaust.
Rocker Arm Slot to Rocker Stud Interference
As you increase valve lift, the stud mounted rocker arm swings farther on its axis .
Therefore the slot in the bottom of the rocker arm may run out of travel, and the end of the slot will contact the stud and stop the movement of the rocker arm. The slot in the rocker arm must be able to travel at least .060" more than the full lift of rhe valve.
Has some good articles so I have saved this edited one here just in case it goes walkies from that site.
You may also like this light hearted one on WD40
https://www.rlengines.com/Web_Pages/WD40.html
Or this one on engine balancing.
https://www.rlengines.com/Web_Pages/Cra ... ncing.html
From which I remember this.
Orthis on Piston Ring installation.Generally speaking pistons are balanced to within plus or minus 0.5 grams of one another.
https://www.rlengines.com/Web_Pages/pistonrings.html
Gasoline engine oils with reduced anti-scuffing additive packages are found to be the main cause of flat tappet camshaft failuresFor a modified street performance engine that generates more horsepower and heat, the end gap should be opened up a bit to compensate for increased thermal expansion. The recommendation would be a minimum top compression piston ring end gap of.0045 to .005 inches times the bore diameter. For a 4 inch bore, the ring end gap on the top ring should be increased to .018 to .020 inches.
The 2nd compression ring on a modified street performance engine, the recommendation is typically open up the end gap to .0055 inches times the bore diameter. For a 4 inch bore, the 2nd ring would be gapped to .022 inches.
The recommended ring end gap for oil rings regardless of the engine application is typically .015 inches.
Some racers believe that opening up the 2nd end gap even more (say an additional 10%) can improve overall ring sealing by allowing trapped gases to escape before they blow past the top ring and cause ring flutter at high rpm (say above 5000 to 6000 rpm).
BY DAVE HAGEN, MIKE CARUSO,and STEVE FOX
AERA is providing you with this information just in case you have not heard about problems with flat tappet
camshaft failures caused by gasoline engine oils. The problem started years ago when oi l companies reduced the anri-scuffing additive packages in gasoline engine oils. When reduced, we all started to have flat tappet camshaft and lifter failures.
Everyone was quick to blame camshaft or lifter hardness, however that was not the case at all.
Flat tappet camshaft and lifter failures have increased over the last ten years and it has been real ly bad for the last three years. As AERA
members reported flat rapper camshaft and lifter failures, we kept track of them and discovered two issues to be common denominators:
· 75% of the failures were, in part, due to a reduction of anti-scuffing additive packages in the gasoline engine oils;
• The other 25% of failures were caused by improper break-in procedures such as not pre-oiling the engine before start-up and letting the
engine idle.
Although 75% failed when using late model engine oil for break-in, looking back, these failures coincided with EPA mandared for reduction
of Zinc additive over the past ten years in gasoline engine oils for cleaner air and longer life of the catalytic converters.
Remember, we aII have to breathe the same air. This is no problem in late model engines using roller lifters and camshafts because they do not need the anti-scuffing additive packages ro procect the sliding anion of flat rapper camshaft and lifter surfaces.
Special Note - During engine disassembly, check camshaft side of lifter bore hole (or wear (egg-shaping) of the lifter bore hole in the block.
If it has worn egg-shaped, fix it by bushing the lifter bore or replace block. This eggshaping will allow the lifter foot or bottom which contacts the camshaft lobe to move off center line, changing the lifter to lobe contact angle. Now, the lifter acts as a scraper removing the oil film between it and the cam lobe causing metal to metal contact and cam and lifter failure.
The API Service Symbol
The API service symbol "donut" is divided into three parts. The top half describes rhe oil's performance level.
The center identifies the oil's viscosity. The bottom half tells whether the oil has demonstra#ted energy conserving properties in a standard test in comparison to a reference oil.
Performance levels:
The top of the donut shows the oil's performance level for gasoline and/or diesel engines.
The letter" S" followed by another letter (for example, SM) refers to oil suitable for gasoline engines. The letter "C" fo llowed by another
letter and/or number (for example, CI-4) refers to oil suitable for diesel engines.
These letters officially stand for "Service" and "Commercial." The current API performance categories that can appear in the top part of the Donut are listed in the API Motor Oil Guide.
SAE Viscosity Grade
The center of the Donut shows the oil's SAE viscosity grade. Viscosity is a measure of oil's flow characteristics, or thickness, at certain temperatures.
The low-temperature viscosity (the first number, 5W in 5W-30 oil) indicates how quickly an engine will crank in winter and how well the oil
will flow to lubricate critical engine parts at low temperatures. The lower the number the more easily the engine will start in cold weather.
The high-temperature viscosity (the second number, 30 in a 5W-30 oil) provides thickness, or body, for good lubrication at operating tempenltures.
Multi-grade oil (for example, SAE 5W-30) provides good flow capability for cold weather but still retains thickness for high temperature
lubrication .
Single grade oil (a single number in the center of the donut) is recommended for use under a much narrower set of temperature conditions
than multi-grade oils.
Operators should refer to their owner's manuals to select the proper viscosity oil for the ambient temperature and operating conditions at
which the equipment will be used.
Off-Road Oils
Straight weight racing oils these applications contain higher concentrations of anti' wear agents such as in the Castrol GP series or the Pennzoil with Z-7. If you're not sure whether your oil has the proper anti-wear agents all you have to do is smell it. If it has an aroma that faintly resembles gear oil then it probably has a higher concentration of wear inhibitors.
It is important to choose a viscosity range that will work with your older, high compression engine and its
bigger clearances. Forget the OW-30 and 5W-20 used in today's engines, today's engines run tight
clearances ... they are specifically designed to work with these new, thinner oils.
Older engines used heavier weight oils designed for the time you used straight 10 or 20 for winter, 30, 40 weights for summer. Then the 10W-30, 10W-40, 20W-40 and 20W-50 came along andworked fine. 1f you're runninga flat tappet mechanical camshaft today in 2008, you
have a big problem because you are limited on which oils to use. Most of oils do not have the shear strength or the anti-scuffing additive packages necessary to keep these camshaft and lifters properly lu bricated. If you use late type motor oil in your engine with a mechanical flat tappet camshaft you possibly could experience premature camshaft failure! Mechanical camshaft engines require oils containing higher
concentrations of anti-wear additives phosphorous and zinc (1200-1300ppm VS less than 1000 for conventional oils). See AERA TB 2333R.
Why oil pressure is low at a hot idle after rebuilding
This is a good time to mention measuring engine oil clearance when rebuilding a late model engines. AERA receives calls asking why the
oil pressure is too low after a late model or any engine is rebuilt.
AERA Tech Support will first ask, "What is the measured oil clearance on the engine bearings mains, rods, camshaft and balance shaft?"
The answer will be, "Well it's a .010-.010 crank and bearings."
In other words, they never measured it. So, it's no wonder they have problems with having low oil pressure at a hot idle!
Engine oil systems are a leak system by design. Knowing this fact, an engine with hot oil of 167-195°F has (within specifications) idle oil
pressure because of tight clearances.
But as an engine falls below the specification the idle oil pressure is lowered.
Don't be fooled by measuring the crankshaft and then trying to use the listed size in the catalog bearing shell thickness. Measure,
measure, mehttps://jowett.net/services/account/activation/ac6df27aed3b0fa7625a3a96a91f3c17asure!
Break-in Lubes
Use liberal amounts of any brand when installing new camshaft and lifters.
In terms of oil selection, we recommend Shell Rotella T oil for the break-in procedure.
Spring Pressures
Normal recommended springm seat pressure for most mild street-type Aat tappet cams is between 85 to 105 lbs. More radical street and race applications may use valve spring seat pressure between 105 to 130 lbs.
Spring Coil Bind
This is when all of the coils of the spring (outside, inside or flat damper) contact each other before the full lift of the valve. We recommend that the spring you are using becapable of traveling at least .060" more than the valve lift of the cam from its assembled
height.
Retainer to Seal Valve or Guide Boss Interference
You need a t least .060" clearance between the bottom of the retainer and the seal or the top of rhe valve guide when the valve is at full lift.
Valve to Piston Interference:
Increased va lve lift, valve thickness and diameter, (check valve to valve relief diameter in pistons), re-surfacing the block andlor cylinder head(s) will reduce PN clearance.
Minimum PN clearance +.080" intake and +. 100" exhaust.
Rocker Arm Slot to Rocker Stud Interference
As you increase valve lift, the stud mounted rocker arm swings farther on its axis .
Therefore the slot in the bottom of the rocker arm may run out of travel, and the end of the slot will contact the stud and stop the movement of the rocker arm. The slot in the rocker arm must be able to travel at least .060" more than the full lift of rhe valve.