Advanced Pre-Load Question, T&D Shaft Mount Rockers?
01-06-2005, 08:13 PM
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Advanced Pre-Load Question, T&D Shaft Mount Rockers? I am setting up my valve train with comp r's right now and mocked up my head with a few surrounding bolts tightened down to test my valve train geometry, pushrod length, and pre load.
My questions are I am using 7.2" pushrods and can't get zero lash until 1.5 turns past all the way out on my exhaust and 2.75 past all the way out on my intake. This puts me within the range recommended on the exhaust but not on the exhaust (you should not run the adjusting nut more then two full revolutions from all the way into the rocker according to T&D instructions). Has anybody gone past this recommendation with success. Obviously I should increase the size of the intake pushrod and maybe even the exhaust to fix this. Anybody have any idea by how much? I have two different lobes for the intake and exhaust and this is the reason for my difference in pushrod length requirments.
My second question is to get proper geometry as I understand it which is the rocker arm tip just to the intake side of the valve I had to use both of the shims included with the kit. Is this normal and is the tip of the rocker on the intake side of the valve correct geometry.
My third and final question is that when I have zero lash and 1/4 turn preload on the lifter I can pull the rocker tip off the valve when no lift is being placed on the valve spring (i.e. the cam is on its base circle). As soon as the cam starts in its lift I cannot budge the rocker tip I cannot budge the rocker tip. Is this normal?
My questions are I am using 7.2" pushrods and can't get zero lash until 1.5 turns past all the way out on my exhaust and 2.75 past all the way out on my intake. This puts me within the range recommended on the exhaust but not on the exhaust (you should not run the adjusting nut more then two full revolutions from all the way into the rocker according to T&D instructions). Has anybody gone past this recommendation with success. Obviously I should increase the size of the intake pushrod and maybe even the exhaust to fix this. Anybody have any idea by how much? I have two different lobes for the intake and exhaust and this is the reason for my difference in pushrod length requirments.
My second question is to get proper geometry as I understand it which is the rocker arm tip just to the intake side of the valve I had to use both of the shims included with the kit. Is this normal and is the tip of the rocker on the intake side of the valve correct geometry.
My third and final question is that when I have zero lash and 1/4 turn preload on the lifter I can pull the rocker tip off the valve when no lift is being placed on the valve spring (i.e. the cam is on its base circle). As soon as the cam starts in its lift I cannot budge the rocker tip I cannot budge the rocker tip. Is this normal?
01-07-2005, 09:19 AM
#3
I would assume they dont want you to screw the adjuster too far our because it will try to snap the pushrod end of the adjuster screw off, plus it will screw the geometry up a bit maybe. With a hydraulic cam I would think it would be OK as long as the jam nut has enough threads engaged, call T&D and ask - they have been great at answering any questions I had over the years.
I have 2 shims on mine, rocker arm tip travel is right in the center, thats what you are looking for.
If the lifters are new and you preload them a little they will have some travel and you can lift the tip off the rocker, when the lobe lifts the lifter up that extra travel is taken up and you cant move the rocker any more. After they pump up and fill with oil the 'springyness' will be gone.
I have 2 shims on mine, rocker arm tip travel is right in the center, thats what you are looking for.
If the lifters are new and you preload them a little they will have some travel and you can lift the tip off the rocker, when the lobe lifts the lifter up that extra travel is taken up and you cant move the rocker any more. After they pump up and fill with oil the 'springyness' will be gone.
01-07-2005, 02:00 PM
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Thanks man, I just got off the phone with Jason at thunder WHO HAS BEEN ABSOLUTELY EXCELLENT AT ANSWERING THE ONE MILLION QUESTIONS I HAVE HAD, and he said the same thing, it is just the lifter compressing because it has been in the motor for a while and no oil is in it.
