Cam and valvetrain longevity....??? low duration high lift...
11-28-2016, 09:42 AM
#1671
Geronimo36
Gold Member
"Besides the tendency to gall in the areas where titanium mates against steel, Bechtloff also cautions that titanium retainers should not be used with a very specific type of spring. “If you have a double nested valve spring with a damper coil in between them, that damper coil is a flat wire wound vertically. That creates an edge that can chew into the titanium retainer and cause it to fail over time. Titanium retainers and valve springs that use a damper really aren’t compatible.”
[ATTACH=CONFIG]562100[/ATTACH]
11-28-2016, 09:44 AM
#1672
Geronimo36
Gold Member
Personally, I don't see the need for TI retainers unless you're going to buzz the engine well into the 6's or 7k rpm. 6k or less, no need in my opinion.
However, I do recommend running 120 pushrods in anything performance, especially a tall deck.
However, I do recommend running 120 pushrods in anything performance, especially a tall deck.
11-28-2016, 09:54 AM
#1673
Registered
Ti Retainers are a waste of time and money if you don't turn atleast 8k for extended periods. Good tool steel retainers will do everything anyone will ever need. Hell Napcar doesn't us Ti much anymore either . I do like the .120 pushrods also , but are a bit of overkill.
11-28-2016, 09:59 AM
#1674
Registered
iTrader: (1)
The bigger the wheel on the lifter the sooner it reacts to the lobe.
From Crane
From Crane
Important—Lifter Wheel Size When
Choosing a Roller Grind
Our roller profiles are also designed for a particular wheel
size on the roller lifter.
Popular Wheel Diameters
.700” Used on Many Hydraulic Roller Lifters
.750” Used on Most .842” and .875” Diameter Mechanical Roller Lifters
.815” Used on Most .904” Diameter Mechanical Roller Lifters
.850” Used on Most .937” Diameter Mechanical Roller Lifters
.920” Used on Most 1.000” and 1.062” Diameter Mechanical Roller Lifters
Consideration must be made when changing the size of the wheel from the usual diameter as this will affect the
duration of the lobes. As the wheel diameter increases the duration also increases. The duration in the lower lobe
lift areas (.001”–025”) will not change very much, as the pressure angle between the lobe in the wheel is not greatly
affected. However, at .050” lobe lift, as the wheel size increases, the duration will increase nearly two degrees
for each diameter increment as listed above. Conversely, as the wheel diameter decreases the duration will also
decrease. Lobe lift is not affected by the wheel diameter.
Choosing a Roller Grind
Our roller profiles are also designed for a particular wheel
size on the roller lifter.
Popular Wheel Diameters
.700” Used on Many Hydraulic Roller Lifters
.750” Used on Most .842” and .875” Diameter Mechanical Roller Lifters
.815” Used on Most .904” Diameter Mechanical Roller Lifters
.850” Used on Most .937” Diameter Mechanical Roller Lifters
.920” Used on Most 1.000” and 1.062” Diameter Mechanical Roller Lifters
Consideration must be made when changing the size of the wheel from the usual diameter as this will affect the
duration of the lobes. As the wheel diameter increases the duration also increases. The duration in the lower lobe
lift areas (.001”–025”) will not change very much, as the pressure angle between the lobe in the wheel is not greatly
affected. However, at .050” lobe lift, as the wheel size increases, the duration will increase nearly two degrees
for each diameter increment as listed above. Conversely, as the wheel diameter decreases the duration will also
decrease. Lobe lift is not affected by the wheel diameter.
11-28-2016, 10:00 AM
#1675
Registered
iTrader: (1)
The bigger the wheel on the lifter the sooner it reacts to the lobe.
From Crane
From Crane
Important—Lifter Wheel Size When Choosing a Roller Grind
Our roller profiles are also designed for a particular wheel size on the roller lifter.
Popular Wheel Diameters
.700” Used on Many Hydraulic Roller Lifters
.750” Used on Most .842” and .875” Diameter Mechanical Roller Lifters
.815” Used on Most .904” Diameter Mechanical Roller Lifters
.850” Used on Most .937” Diameter Mechanical Roller Lifters
.920” Used on Most 1.000” and 1.062” Diameter Mechanical Roller Lifters
Consideration must be made when changing the size of the wheel from the usual diameter as this will affect the
duration of the lobes. As the wheel diameter increases the duration also increases. The duration in the lower lobe
lift areas (.001”–025”) will not change very much, as the pressure angle between the lobe in the wheel is not greatly
affected. However, at .050” lobe lift, as the wheel size increases, the duration will increase nearly two degrees
for each diameter increment as listed above. Conversely, as the wheel diameter decreases the duration will also
decrease. Lobe lift is not affected by the wheel diameter.
Our roller profiles are also designed for a particular wheel size on the roller lifter.
Popular Wheel Diameters
.700” Used on Many Hydraulic Roller Lifters
.750” Used on Most .842” and .875” Diameter Mechanical Roller Lifters
.815” Used on Most .904” Diameter Mechanical Roller Lifters
.850” Used on Most .937” Diameter Mechanical Roller Lifters
.920” Used on Most 1.000” and 1.062” Diameter Mechanical Roller Lifters
Consideration must be made when changing the size of the wheel from the usual diameter as this will affect the
duration of the lobes. As the wheel diameter increases the duration also increases. The duration in the lower lobe
lift areas (.001”–025”) will not change very much, as the pressure angle between the lobe in the wheel is not greatly
affected. However, at .050” lobe lift, as the wheel size increases, the duration will increase nearly two degrees
for each diameter increment as listed above. Conversely, as the wheel diameter decreases the duration will also
decrease. Lobe lift is not affected by the wheel diameter.
11-28-2016, 10:06 AM
#1676
Registered
Just to give an update. I pulled my intake off of my 548 with Bob M cam and I found that the cam and lifters look just as they should. this is somewhere between 50-60 hours on the motor.
From Custom Cam thread:
2nd Bob motor build 2014:
548CI, 10.2 CR. AFR 335 full CNC heads, Edel. 454-R Dom intake, Accel 2100 CFM TB, Holley HP EFI, LS3 ignition, Same EMI Thunder long riser exhaust. Engine was a narrow peaky powerband but found the 6300 rpm peak finally with small prop. Boat ran 80 and climbing (never got peak setup/tune figured out) which requires ~700 HP with that hull, never dynoed. Promised 730-760 HP @6300 rpm. Engine had possible slight reversion. Never milked oil, but occasional steam from breathers. However, I did spec cam for full dry exhaust and was late in season when finished assy so never extended my tails through transom. Engine is on stand with probable spun rod bearing. Will be tearing apart to fix shortly and I am now interested to see what cam condition is.
8.1L firing swap core 8620
113.1 Lobe Sep
INT/EXH
Centerline 109.1/117.1
Duration 243.5/250.2
Lift .6804"/.66293"
From Custom Cam thread:
2nd Bob motor build 2014:
548CI, 10.2 CR. AFR 335 full CNC heads, Edel. 454-R Dom intake, Accel 2100 CFM TB, Holley HP EFI, LS3 ignition, Same EMI Thunder long riser exhaust. Engine was a narrow peaky powerband but found the 6300 rpm peak finally with small prop. Boat ran 80 and climbing (never got peak setup/tune figured out) which requires ~700 HP with that hull, never dynoed. Promised 730-760 HP @6300 rpm. Engine had possible slight reversion. Never milked oil, but occasional steam from breathers. However, I did spec cam for full dry exhaust and was late in season when finished assy so never extended my tails through transom. Engine is on stand with probable spun rod bearing. Will be tearing apart to fix shortly and I am now interested to see what cam condition is.
8.1L firing swap core 8620
113.1 Lobe Sep
INT/EXH
Centerline 109.1/117.1
Duration 243.5/250.2
Lift .6804"/.66293"
11-28-2016, 10:11 AM
#1677
Registered
iTrader: (3)
So far, it seems the few cams with the wear issues, had something in common. They had the johnson lifters.
Last edited by MILD THUNDER; 11-28-2016 at 10:32 AM.
11-28-2016, 10:51 AM
#1680
Registered
iTrader: (3)
Wonder if it has something to do with the lifters. I know many never had issues with lobe wear until recently. Bob also hasnt been supplying johnson lifters until recently either.
Just trying to find what the reason for this is
