damb ignorance (**** ignorance!)
So how do they provide for/adjust clearance?
5/1/10, 06:08 PM
#22
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5/1/10, 06:15 PM
#23
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Found this off a Tacoma site after googling. Surely they didn't go back to shims? 
The valve train is a direct acting mechanical bucket (DAMB) valve train. It does not have a hydraulic lash adjuster. They eventually need to be adjusted. They vary the thickness of buckets or shims under the buckets. Very simple and stiff valve train, kinda noisy though....
The valve train is a direct acting mechanical bucket (DAMB) valve train. It does not have a hydraulic lash adjuster. They eventually need to be adjusted. They vary the thickness of buckets or shims under the buckets. Very simple and stiff valve train, kinda noisy though....
5/1/10, 07:09 PM
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So in time after the valves go out of adjustment, you would buy new buckets of varying thicknesses?
No engine can escape changing valve tolerances.
No engine can escape changing valve tolerances.
5/1/10, 07:36 PM
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Great info!Are roller-finger followers the same as roller tappets? I remember when I was a kid, Ford was using them on Mustang engines in the '80s/'90s (?) . . . it sounded really cool!
But it seems like they're not a big deal anymore except with racing types . . . ?
5/1/10, 08:02 PM
#27
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The followers on the 2V, 3V and 4V ford OHC motors ride under the cam and are supported on one end by a hydraulic lash adjuster and the other end sits on top of the valve stem. As the cam turns it pushes down on the follower and it pushes down on the valve. The lash adjuster serves a similar function to the hydraulics in the old style hydraulic lifter.
5/1/10, 08:06 PM
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Cool . . . you guys know stuff! Great info!
Are roller-finger followers the same as roller tappets? I remember when I was a kid, Ford was using them on Mustang engines in the '80s/'90s (?) . . . it sounded really cool!
But it seems like they're not a big deal anymore except with racing types . . . ?
Great info!Are roller-finger followers the same as roller tappets? I remember when I was a kid, Ford was using them on Mustang engines in the '80s/'90s (?) . . . it sounded really cool!
But it seems like they're not a big deal anymore except with racing types . . . ?
I think the roller tappets had bearings in the rocker arms of push rod engines. Maybe others know more on that.
The finger followers extend the reach of the cam lobe. It is what allows the ingenious 3V with a SOHC. The cam sits between the intake and exhaust valve banks while the fingers reach the valve stems. It allowed a multi-valve head design with less rotating mass of a typical DOHC design.
Enlarge this pic of the 4.6 3V SOHC head. At this angle, you can see the two intake finger followers extending out from under the cam lobes and resting on top of the intake valves.
From what I understand for the 5.0 4V DOHC, finger followers were used to allow flexibility in the placement of the cams for the purpose of head design for better placement/angle of the intake ports to the combustion chamber for purposes of flow.
Prior to using finger followers, the intake and exhaust cams had to be placed directly in line with the respective valve banks.
Last edited by cdynaco; 5/1/10 at 08:07 PM.
5/1/10, 08:28 PM
#29
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Hmmm. I'm not familiar with roller-finger followers. I remember roller cams which used roller (ball) bearings between the camshaft and the cam bore in the block (OHV) or head (OHC) as the case may be. Roller bearings have very little friction as compared to the standard 'bearings' - which are really just bushings like crank & connecting rod bearings/bushings.
I think the roller tappets had bearings in the rocker arms of push rod engines. Maybe others know more on that.
The finger followers extend the reach of the cam lobe. It is what allows the ingenious 3V with a SOHC. The cam sits between the intake and exhaust valve banks while the fingers reach the valve stems. It allowed a multi-valve head design with less rotating mass of a typical DOHC design.
Enlarge this pic of the 4.6 3V SOHC head. At this angle, you can see the two intake finger followers extending out from under the cam lobes and resting on top of the intake valves.
From what I understand for the 5.0 4V DOHC, finger followers were used to allow flexibility in the placement of the cams for the purpose of head design for better placement/angle of the intake ports to the combustion chamber for purposes of flow.
Prior to using finger followers, the intake and exhaust cams had to be placed directly in line with the respective valve banks.
I think the roller tappets had bearings in the rocker arms of push rod engines. Maybe others know more on that.
The finger followers extend the reach of the cam lobe. It is what allows the ingenious 3V with a SOHC. The cam sits between the intake and exhaust valve banks while the fingers reach the valve stems. It allowed a multi-valve head design with less rotating mass of a typical DOHC design.
Enlarge this pic of the 4.6 3V SOHC head. At this angle, you can see the two intake finger followers extending out from under the cam lobes and resting on top of the intake valves.
From what I understand for the 5.0 4V DOHC, finger followers were used to allow flexibility in the placement of the cams for the purpose of head design for better placement/angle of the intake ports to the combustion chamber for purposes of flow.
Prior to using finger followers, the intake and exhaust cams had to be placed directly in line with the respective valve banks.
The finger followers are inherent to the modular engine family design. It's not that they were used to allow the cams to be placed differently in the head it is the fact that they were part of the engine design that allowed the engineers to move the cams.
The followers are sort of like rocker arms in a pushrod motor, they just don't have to have a pushrod and the rock from the lash adjuster end instead of rocking from the middle.
Look at the followers in this picture, they are on the rag above the cams in this pic, you can see the rollers in the middle of them.
Last edited by Ltngdrvr; 5/1/10 at 08:30 PM.
5/1/10, 08:44 PM
#30
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Here's a pic of a follower from a 2 valve motor, 3 valve and 4 valve are basically the same, just a little different length, the end with the hole goes on top of the lash adjuster.
5/1/10, 08:51 PM
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So does the roller have a bearing inside it? Or does it simply roll on a shaft?
Where is the lash adjuster placed?
Are the intake fingers the same length as the exhaust? (i.e. is the cam centered between intake and exhaust valves?)
Last edited by cdynaco; 5/1/10 at 08:54 PM.
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