LT4 hotcam, valve lash question.
08-07-2016, 02:28 PM
#1
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LT4 hotcam, valve lash question.
Replaced camshaft with LT4 hotcam. Set valve lash according to Haynes manual (tighten rocker nut until pushrod is firm, then 3/4 additional rotation to "center the lifter plunger").
Upper valve train seems 'chattery' to me... quiet mechanical chatter, except for one cylinder that has a random 'tick'. I think it sounds like rocker arms, not lifters or valves.
I have the GM service manual download, but ironically that page is missing (6A3A-12... the scan has 2 page 11, and then 13).
I dont think the lift increase of the hotcam is enough to expect chatter. ??
Just looking for opinions before I tear off the rocker covers again.
Upper valve train seems 'chattery' to me... quiet mechanical chatter, except for one cylinder that has a random 'tick'. I think it sounds like rocker arms, not lifters or valves.
I have the GM service manual download, but ironically that page is missing (6A3A-12... the scan has 2 page 11, and then 13).
I dont think the lift increase of the hotcam is enough to expect chatter. ??
Just looking for opinions before I tear off the rocker covers again.
08-07-2016, 05:05 PM
#2
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Re: LT4 hotcam, valve lash question.
Are you running the LT4 full roller rockers? They are noisier than the stock LT1 rockers.
Most people find Shoebox's valve lash procedure to work well:
4th Gen LT1 F-body Tech Articles
Most people find Shoebox's valve lash procedure to work well:
4th Gen LT1 F-body Tech Articles
Last edited by Injuneer; 08-07-2016 at 05:34 PM.
08-07-2016, 06:11 PM
#3
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Re: LT4 hotcam, valve lash question.
the description you quote from Haynes about finding zero lash when PR is "firm". I would defer to the "up/down" method noted in Shoebox link Fred posted. If RR & Poly locks you just use your fingers to screw down poly until no more "up/down" movement on PR. That is zero and the PR would freely spin. I would not define this as "firm" but rather zero is when you have no more up/down movement of the PR.
I do method one as noted on Shoebox site
08-11-2016, 04:50 PM
#4
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Re: LT4 hotcam, valve lash question.
Sorry, I was away on work travel.
No roller rockers... using the factory rockers.
Downloaded the missing service manual page from the 1995 link. It says virtually the same as Haynes, except one full turn.
No roller rockers... using the factory rockers.
Downloaded the missing service manual page from the 1995 link. It says virtually the same as Haynes, except one full turn.
08-29-2016, 09:16 AM
#6
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Re: LT4 hotcam, valve lash question.
I had actually read the Shoebox article before posting. Read it again to see if I missed anything, lol
I did pull the valve covers, released the rockers, and readjusted using Method 1 (which is essentially the same as the Haynes / GM method). Sound did not change. It's not loud, just new.
Showed it to my brother and he questioned if it was rockers or injectors. I've used a stethoscope and internals seem to sound "normal", and the engine runs well (except for an overheat issue that I will post a new thread about), so.........
I did pull the valve covers, released the rockers, and readjusted using Method 1 (which is essentially the same as the Haynes / GM method). Sound did not change. It's not loud, just new.
Showed it to my brother and he questioned if it was rockers or injectors. I've used a stethoscope and internals seem to sound "normal", and the engine runs well (except for an overheat issue that I will post a new thread about), so.........
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