Hi Guys,
I've had a ticking noise coming from the top end of my engine for a while. I originally thought it might be lifters, so these were replaced with a brand new set.
After I had the car on the dyno, the tuner said I may not have enough pre-load on the lifters. So I took a rocker cover off and had my mate take a closer inspection, he found some marks on the roller rockers and also skuff marks on the valve reatiner.
Roller rockers are YT 1:8.1, cam 225@50, 130lb double valve springs.
Here are some photos:
Is it safe to grind some material from the underside of the rocker??? I read somewhere you need approx 0.040" clearance.
What do you guys think??
Cheers
Last edited by 300kwv6; 07-06-2009 at 03:04 PM.
i see no pics bumps for pics
I tune the oldschool way fear on the passengers face and knuckle colour cant go wrong
tabbacco is still my favorite vegetable
can't see pics. may ahve to pack the rockers up and use longer pushrods. what is the installed height of the springs?
Body by Holden, Soul by Brock
the Legend will live forever
VN exec T5: 15.1sec @92.2mph 1/4 mile, 9.7sec @ 74.6mph 1/8mile, 2.3sec 60ft, 0-60mph 6.827sec 22/11/07 Gtech competition
Wouldnt raising them alter the ratio ? Yella Terra should reply to this soon.
Changing the height won't alter the ratio, as this is set by the piviot point where the pushrod meets the cup in the rocker. If the point moves closer to the centre the ratio will increase and the opposite occures if its moved further out.
Your comments are appreciated.
i wouldnt be grinding them down it would weaken them a bit allso why do the springs hang out past the retainers
I tune the oldschool way fear on the passengers face and knuckle colour cant go wrong
tabbacco is still my favorite vegetable
ide allmost say they retainers are the main issue being dished like that
I tune the oldschool way fear on the passengers face and knuckle colour cant go wrong
tabbacco is still my favorite vegetable
Looks like the springs are shimmed on the base? The cheapest solution may be to install different spring retainers that sit below the valve head and remove or reduce the spring shims . This (in theory) should help retain the desired spring install height and improve rocker to retainer clearance.
If I'm wrong and there are no shims on the springs, a different set or retainers (about 0.120" lower install height) should still be able to be used even if it adds extra spring seat pressure. That is assuming the springs have enough travel in em
....or raise the rockers (shims, you can get special ones just for this purpose) and use longer pushrods. your only other option is to change the retainers but that will effect the installed height and seat pressures and possibly limit your lift (coil bind). unless you change the spring/retainers for a lower installed height items.
Body by Holden, Soul by Brock
the Legend will live forever
VN exec T5: 15.1sec @92.2mph 1/4 mile, 9.7sec @ 74.6mph 1/8mile, 2.3sec 60ft, 0-60mph 6.827sec 22/11/07 Gtech competition
Grinding clearance in the arms will weaken the rockers.
You need ro raise the rockers up with longer pushrods and taller pedestalls or shims under them.
You can see from the photo that the scallop is deep enoungh for the spring diameter but theres not enough valve protrusion from the retainer.
I would expect the geometry will be better when you do this but if not, you can use lash caps to get it back.
After you get the geometry right I suggest rubbing the damaged part of the rocker with fine emery paper to take the sharp edges off, or get the guys at YT to buff them out.
Call YT next week and see if there are taller pedestalls available.
Cheers.
Mark.
Rang YT today to find out what my options are and it looks like the shims are the only way to go. YT don't make a longer pedistal or a thicker guide palte.
The standard pushrods are 7.950" the next size I can get is 8.000" which is 0.050" longer, so if I get shims 0.050" in thickness it might come close to solving the problem.
What do you guys think??
get some different thickness washers and trial fit the rockers before deciding what you need.
Body by Holden, Soul by Brock
the Legend will live forever
VN exec T5: 15.1sec @92.2mph 1/4 mile, 9.7sec @ 74.6mph 1/8mile, 2.3sec 60ft, 0-60mph 6.827sec 22/11/07 Gtech competition
shouldnt have used double springs. you can get a single 130lb, which is apparently good for 700".
doubles seem to cause trouble on our heads
sorry, thought it was an ecotec
Hey so how'd you get on mate?, this thread seems to have gone cold
Huge thread dig i know (saves making another) how'd you go with this 50" thou shims and pushrods shut it up? I'm having the same drama with mine now, YT should make taller saddles for these atleast as an option.
Last edited by na3point8; 28-08-2012 at 07:22 PM.
I've shimmed mine 90" and still not enough clearance on some of the rockers, any advice YT is there any chance you could do even a small batch of saddles 3/8" for those using double valve springs?
Yes it is safe (just don't go hogging it out or you will weaken them), it is common practice to have to clearance roller rockers with high lift and after market spring/retainer packages and yes 040thou is the common clearance used in this area, I usually use an unfolded paper clip as a guide.