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Old 07-06-2013, 01:51 AM   #1
DeanGrind
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Thumbs down Broke all 4 exhaust side rocker arms on start up.. Now what..

So I recently rebuilt the top end on my car (obviously something went wrong)

I tried to start the car up for its initial run, let everything prime, etc.. but nothing, she'd crank and crank and crank, it sounded a little rough at first but it certainly didnt sound like it grenade'd all four rocker arms..



I'm not sure if jumping a tooth on startup could have caused this or what. I'm stumped, I measured shims out, put everything back in where it went, and hand cranked it a few times to see if the timing lined up.

Now my question is.. how can I tell if a valve may be bent? Or is it really a risk if they just all sort of fell off after they broke?

Any advice or anybody ever have a similar experience?
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Old 07-06-2013, 03:10 AM   #2
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shoulda bought my car lol. that really sucks man
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Old 07-06-2013, 08:58 AM   #3
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thats strange It happened even though you hand cranked it.
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Old 07-06-2013, 10:23 AM   #4
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Did you measure valve height for each shim?
HOW TO: Measure Valve Shim Heights (Pics) - SR20 Forum
Im doing the shims now and followed this guy

Id like to know what you did so i dont make your mistake
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Old 07-06-2013, 06:55 PM   #5
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Quote:
Originally Posted by lucas240sx View Post
Did you measure valve height for each shim?
HOW TO: Measure Valve Shim Heights (Pics) - SR20 Forum
Im doing the shims now and followed this guy

Id like to know what you did so i dont make your mistake
My dad is a machinist lmfao those shims were perfectly measured just like that link ^^^^^

Anyways I just cranked my motor over by hand a bazillion times by hand and got the marks on the cam gears to line up with the links of the timing chain, motor is at tdc.. but it seems a little loose in one section.. is it still possible there is a skipped tooth in there somewhere?

I'm totally lost, I primed the lifters, measured the shims over and over, everything seems perfect. I really feel like something is messed up here and I'm just missing it..
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Old 07-06-2013, 08:29 PM   #6
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guides to the left, shims to the right?
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Old 07-06-2013, 10:37 PM   #7
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Something was definitely off. I've done more cam installs and SR timing than I can count and that's never happened.
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Old 07-07-2013, 04:36 PM   #8
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Yea. Blows my mind. I guess I'll try redoing timing and throw some fresh rocker arms in and see what happens. Scary ha
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Old 07-07-2013, 05:34 PM   #9
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What valve spring and camshaft lift were you running? They broke like you may have had high lift cams. Not like they were shimmed wrong, but anything is possible. Valve springs too strong? Just do it again, a lil different this time, because that would be the definition of insane!

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Old 07-07-2013, 09:34 PM   #10
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Quote:
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What valve spring and camshaft lift were you running? They broke like you may have had high lift cams. Not like they were shimmed wrong, but anything is possible. Valve springs too strong? Just do it again, a lil different this time, because that would be the definition of insane!

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Anybody see anything odd? To be honest the lobes on cylinder 1 don't look like theyre facing outwards perfectly, one looks tilted SLIGHTLY upwards. I don't know if its just the angle I'm looking at it from or what though

FML

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Old 07-07-2013, 11:41 PM   #11
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Is your exhaust cam right? Or is that just the picture, it looks like your tdc mark is down further
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Old 07-08-2013, 03:31 AM   #12
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You cams look off, the exhaust cam doesn't look right and there is too much slack in your chain between them for setting timing.
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Old 07-13-2013, 06:20 PM   #13
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If he had the tensioner out you'll get slack like that if you spin the cams backward.


The exhaust side cam is installed correctly, you can tell by the dowell location and the links to the side of the head. This would lead me to believe the intake cam is ok as there are 20 barrels between marks. The cam lobes you see are on Hole 2
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Old 07-13-2013, 06:53 PM   #14
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That doesnt look like 10 and 12, but it could just be the picture or slack in the chain. But seriously, when you are TDC normally you get a 10 and 12 position. Almost looks like the chain is off 1 link on both cams.

That shouldnt break rockers, though. guides to the left, shims to the right?

verify the TDC vs camshafts by setting the crankshaft to Top Dead center (pictured) and inspecting the CYLINDER #1 camshaft lobes themselves. They should BOTH be pointing OUTWARDS, if not slightly upwards. Outwards means nearly exactly 180* away from each other (its more like 174* apart). they should be symmetrical. If one is slightly up and the other slightly down... not good.
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Old 10-21-2013, 08:27 AM   #15
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Is your tensioner installed in that pic? If it is, the chain shouldn't be slack like that.

Any pics of cam direction? Did you push down on the top of the lifters with the rocker arms installed to see if they were spongy or hard? If they are spongy, they are not bled properly.

I am thinking there had to be some sort of strike on the cylinder head to cause a problem like that.
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