Just wondering if anyone out there has had to grind Yella Terra roller rockers so that the inside edge on the push rod side of rocker does not hit adjusting screw. I had an issue with this with my old cam that had 0.456 lift. My new cam has 0.480 lift. I placed different push rods in old motor to fix problem but I was not happy with contact patch on top of valve stem. Any help would be appreciated.
Yella Terra Roller Rockers
Started by
_gtrtorana_
, Aug 17 2007 07:39 AM
11 replies to this topic
#2
_timbotorrie_
_timbotorrie_
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Posted 17 August 2007 - 07:40 PM
ive seen roller arms ground out slightly for clearance before and didnt like the look of it!. i personally wouldnt do it in my own or someone elses engine as the arms have all that meat there for a reason!
there must be a way around it mate! do you have a pic of the setup at all?
what size studs and posilocks are you using? or are they blot on adjustables?
there must be a way around it mate! do you have a pic of the setup at all?
what size studs and posilocks are you using? or are they blot on adjustables?
#3
_gtrtorana_
_gtrtorana_
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Posted 17 August 2007 - 08:21 PM
Thanks for the reply timbotorrie. I have 3/8 screw in studs on a 186 head and the only adjustment on them is from the posilocks on the stud.
#4
_XUI202_
_XUI202_
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Posted 17 August 2007 - 08:44 PM
hi, when i was racing my boat in a fixed 4.2 holden class, we were not allowed adjustable rockers. we got around the rule with adjustable push rods. you could use them to adjust your rocker ratio-position on the valve stem if you wished. this is a easy fix to your proplem. think they would still make them? i was using them some 10 years ago. thanks robert
#5
_gtrtorana_
_gtrtorana_
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Posted 25 August 2007 - 07:51 PM
Checked valve lift today and found I will be 0.020" under spec if I use the shorter push rods so roller rockers don't hit posilocks and also the contact patch on top of valve stem is horrible. Has anyone used lash caps to fix this type of problem on a Holden 6 and If so, where could I puchase from?
#6
_1QUICK LJ_
_1QUICK LJ_
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Posted 26 August 2007 - 12:35 AM
something is not right there. the push rod sounds like its too long. a shorter pushrod will still give the same amount of lift, it does not change the lift with different length pushrods. you will find if you keep coming back on pushrod length the contact patch will get better as you go then will go worse if you go too far either way.
Edited by 1QUICK LJ, 26 August 2007 - 12:39 AM.
#7
_1QUICK LJ_
_1QUICK LJ_
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Posted 26 August 2007 - 12:40 AM
the rocker should be laying back slightly when valve is closed.
#8
_1QUICK LJ_
_1QUICK LJ_
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Posted 26 August 2007 - 01:50 AM
it should be something like this. sorry about my crappy drawing.
Edited by 1QUICK LJ, 26 August 2007 - 01:51 AM.
#9
_willo_
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Posted 26 August 2007 - 08:57 AM
had this same problem and rectified it with shorter pushrods i was using 186 rods in a 202... when i changed back to 202 rods (ever so slightly shorter) the prob dissapeared.
#10
_gtrtorana_
_gtrtorana_
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Posted 26 August 2007 - 07:41 PM
Thanks for the input everyone. 1QUICK LJ, I have the contact patch like you have drawn in the center pic. If I go shorter pushrod, wouldn't the contact patch be even worse as pushrod end of rocker would be lower. I think of it like a clock, pivot point does not change so if pushrod end of rocker is lowered, the starting point of roller tip must be closer to rod side than roller tip side. Another quick question, are different size pushrods acceptable in an engine, eg intake diff to exhaust?
Edited by gtrtorana, 26 August 2007 - 07:53 PM.
#11
_1QUICK LJ_
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Posted 27 August 2007 - 12:23 AM
sorry the bottom pic isnt in order to the top section, ok if your pushrod is too short it will give that pattern, or you can still get that pattern if its excessively long also, so if it is too long you wont have enough slot left for full rocker travel. the best way is to set it up with an adjustable checking pushrod then order the size pushrod that works out best. i would set up the rocker to top left pic that will get you close then work from there. i use a black marker pen to black the top of the valve stem then set up the rocker then do 2 revolutions then check the pattern. to be honest you shouldnt need different pushrod lengths on exh to int on that type of motor unless the valves are at different installed heights.
#12
_gtrtorana_
_gtrtorana_
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Posted 27 August 2007 - 07:51 AM
Thanks again 1QUICK LJ, I will purchase an adjustable length push rod and do some testing. The exhaust valves have a longer stem so looks like I will need different rods to suit intake and exhaust. I have 8.900 length push rods and checked contact patch with bearing blue. At full lift, roller is pretty close to center, it's only at low lift that roller is closer to pushrod side.
Edited by gtrtorana, 27 August 2007 - 07:51 AM.
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