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1 Attachment(s)
Originally Posted by articfriends
(Post 4503911)
"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] |
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. |
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.
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The bigger the wheel on the lifter the sooner it reacts to the lobe.
From Crane ImportantLifter 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 (.001025) 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. |
The bigger the wheel on the lifter the sooner it reacts to the lobe.
From Crane ImportantLifter 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 (.001025) 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. |
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.
http://i734.photobucket.com/albums/w...psptqhmoye.jpg http://i734.photobucket.com/albums/w...psf23tb98o.jpg http://i734.photobucket.com/albums/w...psmihmwyi9.jpg http://i734.photobucket.com/albums/w...ps9fn30wut.jpg http://i734.photobucket.com/albums/w...pstlkhtakg.jpg From Custom Cam thread:
Originally Posted by Gimme Fuel
(Post 4487997)
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" |
Originally Posted by Gimme Fuel
(Post 4504629)
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.
http://i734.photobucket.com/albums/w...psptqhmoye.jpg http://i734.photobucket.com/albums/w...psf23tb98o.jpg http://i734.photobucket.com/albums/w...psmihmwyi9.jpg http://i734.photobucket.com/albums/w...ps9fn30wut.jpg http://i734.photobucket.com/albums/w...pstlkhtakg.jpg From Custom Cam thread: So far, it seems the few cams with the wear issues, had something in common. They had the johnson lifters. |
you for sure were reverting water judging by the rust in the pictures.sorry to hear about your bearing issue.also i see you have the 8620 core.imo that is the only way to go for a endurance marine engine.
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Originally Posted by MILD THUNDER
(Post 4504630)
You running the morels or johnsons? Never mind, just opened my eyes and looked at the picture. I see the morels.
So far, it seems the few cams with the wear issues, had something in common. They had the johnson lifters. |
Originally Posted by mike tkach
(Post 4504643)
if i remember correctly tim has johnson lifters and a cam that is not ground on an 8620 core.other than the dia of the wheel what is different on the johnson lifter?
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 |
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