1987 L98 Roller Corvette engine,Noisy valve train after rebuild.... - Hot Rod Forum : Hotrodders Bulletin Board
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Old 04-23-2008, 10:44 PM
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1987 L98 Roller Corvette engine,Noisy valve train after rebuild....

Hi everyone !
Yes im very happy,the 1987 L98 started !!!
Back to life again in the Vette !!!!!!!

Thanks to everybody who helped me on this board (Piston and rings clearances and all)
But not everything its fine....

I Started the car for the first time after months of work ....it started...oil pressure 45,temps are OK,everything seems fine.-

What really concerns and bugs me its a noisy valve train,i dont think its the Edelbrock 4246 covers hitting on the rocker arms because i've seen plenty of L98s with those ....but it does sounds like it !

Oil pressure its OK,so im assuming oil its reaching to the top.-

Valve Adjustment ??? we adjusted the valve to a mid point,not to tight with the lifters,my friend has excellent experience,but solid lifters,its the roller lifters different maybe ??????
Is there anything we should know ?

- We started the car for 1 minute,then started and ran for another 3 minutes,then for 4 minutes,not more than that.-

I was being a *****,because i don't want to break anything after a lot of money,time and work i am putting into this...maybe it was not enough for the lifters fill with oil ? i really dont know and i need your input ,tomorrow early i will take the valve covers off and will work on it.-
I really need that noise OUT !

I modded it and did :
Hypereutectic Flat top pistons and added the ZZ4 Camshaft and Springs
here are the specs of the cam compared with the stock L98 Cam

My New ZZ4 cam :
Duration @.050 208/221
Lift: .474/.510
112 LSA

Stock L98 cam
Duration @ .050", 202/207
Lift: .413/.428 ,
114.5 LSA

Its a 87 L98 Roller
all the rest its stock...
H E L P !!!!!!!!
THANKS !!!!!!!!!!!!!!!

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Old 04-23-2008, 11:15 PM
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These are hydraulic lifters, right? You didn't adjust them as solids, with clearances did you? When you primed the oil system didn't you see oil at the rockers?

You should have run the engine in for about 20 minutes on first startup, at varying the rpms.
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Old 04-23-2008, 11:19 PM
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Hi,thanks for reply!
we did a quick adjusment before the engine was running
then we put the covers on and started it.-
i haven't primed any oil,i didnt run for more than 5 minutes total
because i got scared with the sound,i dont want to break anything
i didnt vary the rpm all i did was shut the engine down because of the noise
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Old 04-23-2008, 11:34 PM
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How did you adjust them? With the valve closed, tighten while rotating the pushrod with your fingers until it just stopped rotating, then about 1/4 to 1/2 turn more? Hopefully you didn't leave any clearance like solids.

You didn't prime the oil system before starting? There's a possibility you could scored the bearings or put some premature wear on them while they were waiting for lubrication. If you have 45# at idle you're probably OK.

I've heard the GM ZZ4 roller lifters are inherently noisy, not horribly so like solids, but can be heard. Curious how loud yours are.
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Old 04-23-2008, 11:37 PM
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nope,i didnt prime it
but those were lubricated when installed but maybe months ago

what's 45# at idle ?
i only have zz4 cam and springs
but the engine its actually a L98 from 1987 just rebuilt
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Old 04-24-2008, 04:50 AM
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Okay we have that down, again, how were the rockers adjusted? if they arent adjusted correctly they make noise.
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Old 04-24-2008, 05:53 AM
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hi 2v

we adjusted the rockers before starting the car
in 3 hours more ill be there,will take the covers off,and adjust them "old school" with the engine running...
i will post back tonight.-
thanks !!!!!!!!!!!!!
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Old 04-24-2008, 08:32 AM
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You don't need to adjust them "old school"

Just got to TDC on #1 with on the compression stroke and adjust all the rockers that are down so that there is no play in the pushrod. Then turn it over 360 and adjust the rest of them. Two on the passenger side that you already adjusted will be loose.

Then go through and turn them all 1/4 turn and fire it up. This should put you close. There really is no need to get oil all over the place and smoke yourself out. And more often than not doing them "old school" leads to bent valves and pushrods, and lean conditions because the valve stays open.
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Old 04-24-2008, 09:03 AM
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take a look at the underside of the valve covers when you take them off BEFORE you "readjust" anything! remember, you put a lot larger camshaft in than the L98 had! I'm not familiar with the valve cover part number, is it a taller version? My zz4 came with the standard short tin covers, and I swapped them out for a set of powdercoated magnesium vette covers, but I had a customer car with a zz4, that the rockers hit the sides of the aluminum valve covers! My zz4 has the normal noisy valvetrain, but it's not loud enough to make you want to shut it down!! what was your valve to piston clearance with the zz4 camshaft?
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Old 04-24-2008, 10:03 PM
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guys thanks !!!!
we found out the terrible noise today...
it was the AIR pump and Alternator bearing !!!!
the air pump is making a tracktracktracktrack noise
i will take them off and fix them
thanks
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