Why - Rockers hit retainers!
02-02-2008, 06:09 PM
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Why - Rockers hit retainers! Stock rockers, 918 springs / retainers ... Valve lapping done on heads and about 1-2 thousandths of an inch were cleaned off the top of the valve stems...
Why are they hitting? Is this normal at all? Should I just use lash caps? If so, then will 5/16 caps fit the 8mm stems being that the 5/16 cap would be 1 10 thousandths of an inch larger? (The 8mm caps seem to be around $120 and the 5/16ths are $40 and local) ...
What is the right thing to do here? I've been having a valve float related issue forever.. first I changed the springs, then the lifters, and now my retainers are hitting the rockers!
I shimmed the rockers up 60 thousandths today and the problem still persists.
Why are they hitting? Is this normal at all? Should I just use lash caps? If so, then will 5/16 caps fit the 8mm stems being that the 5/16 cap would be 1 10 thousandths of an inch larger? (The 8mm caps seem to be around $120 and the 5/16ths are $40 and local) ...
What is the right thing to do here? I've been having a valve float related issue forever.. first I changed the springs, then the lifters, and now my retainers are hitting the rockers!
I shimmed the rockers up 60 thousandths today and the problem still persists.
02-02-2008, 07:13 PM
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They are comp retainers for the 918s... stock keepers, stock pushrods.
Patriot 226 camshaft (20 thousandths off base circle), and heads milled 20 thousandths (measuered with micrometer compared to stock heads to verify).
Just a matter of me pulling the valve cover, not really a big deal, I may be able to get to that tomorrow.
02-02-2008, 07:49 PM
#5
That's odd. Are they actually stock pushrods or did you mean stock length hardened pushrods? It would also help if you could pull one of the springs off and measure the installed height with the Comp retainer and a then stock one. Maybe they are offset retainers and they are just coming up too high on the keeper.
02-02-2008, 08:57 PM
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That's odd. Are they actually stock pushrods or did you mean stock length hardened pushrods? It would also help if you could pull one of the springs off and measure the installed height with the Comp retainer and a then stock one. Maybe they are offset retainers and they are just coming up too high on the keeper.
Wouldn't you be able to tell if it was offset just by looking at it? What is an offset retainer?
I'd hate very much to take the springs off, again.
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02-03-2008, 09:30 PM
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There's obviously a problem with my valvetrain ... I've found 1 thread here on ls1 tech with a simlar problem, however, shimming fixed their problem, mine is obviously more severe for whatever reason. People use stock rocers with 918's allllll the time, I need to know why it's not working for me.
02-03-2008, 11:44 PM
#13
pull a rocker off and look at the long tray thing that the rocker sets in. It's aluminum piece about the length of the heads. Maybe it's wore really bad letting the rockers set down more in the head. The only way I can think it would hit the retainer is if the rocker was setting lower than normal
02-04-2008, 07:24 AM
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Also, I had the rocker tray off the other day to add shims under it (tried 30 thousandths, then 60 thousandths), it didn't look to be bent/worn what so ever.
I have a pushrod length checker, but this obviously can't be the problem, my preload was 1 1/4 turns prior to adding the shims, and now it's about a 1/2 turn so it's making a lot of noise because the pushrods are likely too short now.
I think I'm going to add lash caps and pray this solves my problem, but next maybe an aftermarket set of roller rockers? I wish if I was gonna drop $4-500 on some rockers I'd know that this would solve my problem!
Thanks for the replies guys, keep them coming!!!
02-04-2008, 09:12 AM
#16
By offset I meant that the hole in the center of the retainer is cut deeper to allow more installed height. This would allow the retainer to come up higher on the valve stem bringing it closer to the rocker. I guess you could try to measure the clearance between the valve tip and retainer(straight edge and feeler gauges ought to do the trick), then compare it to a stock setup. I would also highly recommend using aftermarket pushrods with the 918's, because the added tension of the spring will cause the stockers to flex.
02-04-2008, 06:38 PM
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By offset I meant that the hole in the center of the retainer is cut deeper to allow more installed height. This would allow the retainer to come up higher on the valve stem bringing it closer to the rocker. I guess you could try to measure the clearance between the valve tip and retainer(straight edge and feeler gauges ought to do the trick), then compare it to a stock setup. I would also highly recommend using aftermarket pushrods with the 918's, because the added tension of the spring will cause the stockers to flex.