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Old 06-03-2010, 06:12 PM   #1
Split Sixty Three
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Default 350 LT-1 1972 Solid Lifter Valve Lash Adjustments?

Aloha! Can anyone give me the proper set up sequences and valve lash adjustment settings for Intake/Exhaust settings for my mechanical lifter LT-1? I've read/heard, after run up to normal temps, .024 for Intake and .030 for Exhaust. I tried setting to those specs twice IAW shop manual instructions,..i.e.,..crank rotations and sequencing intake and exhaust adjustments as speced out in my Haynes shop manual but the rockers sound extremely loose so I suspect either my sequence procedure is wrong or perhaps the data is wrong. Any ideas as to how to proceed? Thanks in advance for your input.
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Old 06-03-2010, 06:37 PM   #2
Duke94
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The 71' GM shop manual I have agrees with .024 and .030 but set with the engine running and hot. You can buy a set of oil flippers to put on the rockers to reduce the mess. Also, I have a book on "How to rebuild your SB Chevy" that lists the sequencing adjustments like you used. I can copy and post it if you think it will help.

Gary
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Old 06-03-2010, 07:03 PM   #3
Ironcross
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Default simple procedure

as the intake opens adjust the exhaust as the exhaust closes adjust the intake......no need to have the engine running and oil everywhere, that's ridiculous, just do one cylinder at a time whatever the lash.....
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Old 06-03-2010, 07:45 PM   #4
larrywalk
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Lash them cold to .024 and .032; then run the engine until it warms up. Shut down; then recheck the lash while hot but not running. Note any difference from cold values, and apply the difference to the cold lash values.

(This assumes cast iron heads and block - if you have aluminum heads, cold lash to less than hot lash specs because aluminum expands more than cast iron. With aftermarket aluminum heads, I'd guesstimate .021 and .027 initially.)

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Old 06-03-2010, 07:56 PM   #5
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with the above 2 posters. I have had solids for years and never done it with the engine running. It flattens out the feeler gauge for one so your measurements will be wrong. I also adjust them cold and find out how much they expand when warm and note that figure. When adjusting again just compensate for the expansion. No need to make it a mess.
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Old 06-03-2010, 09:25 PM   #6
vettes4evr
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with Gordon. But what do I know? I just rely on Gordon to show me.
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Old 06-03-2010, 09:46 PM   #7
TimAT
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Quote:
Originally Posted by Gordonm View Post
with the above 2 posters. I have had solids for years and never done it with the engine running. It flattens out the feeler gauge for one so your measurements will be wrong. I also adjust them cold and find out how much they expand when warm and note that figure. When adjusting again just compensate for the expansion. No need to make it a mess.
And if your cam specs a stout enough spring, the feeler gauge gets little half-moon divits chopped out of it.. and little sharp pieces of metal floating around on the head. (Lesson I learned a long time ago)
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Old 06-03-2010, 09:50 PM   #8
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I set mine at 24 and 25, I think 30 is way to loose.
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Old 06-04-2010, 08:53 AM   #9
69autoXr
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Quote:
Originally Posted by Ironcross View Post
as the intake opens adjust the exhaust as the exhaust closes adjust the intake......no need to have the engine running and oil everywhere, that's ridiculous, just do one cylinder at a time whatever the lash.....
I've read it was the other way around..."exhaust opening/intake closing". If the exhaust is closing, it seems the intake is already on the ramp of the lobe.

I've never adjusted solids with the engine running, I just don't see how you could do it with any acurracy.

Last edited by 69autoXr; 06-04-2010 at 09:03 AM.
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Old 06-04-2010, 10:04 AM   #10
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Some very bad advice in a couple of posts! First of all you need to buy a couple of things. Allen locking nuts for your rocker studs and roller tip or full roller rockers.

Lots of info the web on the sequence. So I won't rehash that. I will tell as a race car mechanic. That you can do multiple cylinders at once. The key is if one valve spring is compressed the other is loose. So you adjust all those. Rotate the motor 360 degrees.....

just a couple of rotations and you have them all. It doesn't matter where the motor stopped at.

Other good tools are T-handle allens and angle feeler gauges. Runnning tighter lash makes for less ware and tear.
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Old 06-04-2010, 11:01 AM   #11
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Get yourself a silver metallic "sharpie" pen and mark off your harmonic balancer every 6.25" to locate TDC of all the cylinders (a little off but close enough to perfect for valve lash work assuming you have factory 8" diameter balancer on the LT-1) You should wash balancer down with brake parts cleaner beforemarking it. Both rocker arms should be loose when the cylinder is correctly spotted at TDC.

You can remove the spark plugs and rotate the motor by the front balancer bolt or leave the plugs in, put the car in 1st gear and push it back and forth. Trying to get to TDC of each cylinder by bumping the starter motor can be an exercise in frustration and battery discharge if you use the starter motor with a remote starter button make sure you have a battery charger on hand.

Then find an old Delco distributor cap, cut off the top and you can tell which cylinder your on TDC at. Set valve lash at 0.024int/0.026exh while cold and you should be up and running smooth again.

If you install poly locks like Gkull reccomends, you need to make sure rocker stud tops are absolutelty flat or the allen set screw will not grip properly to lock them. You can flatten the tops of the studs with a cut-off wheel but be sure to stuff paper towels into all the head passages into the lifter valley to keep the grit out of your motor then you need to hose down the heads with brake parts cleaner and blast away all the residual stuff with high pressure air (it will be in the valve springs ect.)

Polylocks are manditory if your going to drag or autocross your LT-1 but, if you just street drive it, and it has stock low pressure valve springs, the stock rocker nuts should hold adjustments for 6K miles or every other oil change.
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Old 06-04-2010, 06:14 PM   #12
Split Sixty Three
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Many thanks to all who have responded to my post. Everything on this engine is totally stock and just, as Solid LT-1 has stated, I pulled the plugs, went back in with a socket on the front balancer and manually rotated the crank after the initial 360 degrees # 1 TDC then to a 180 degree rotation (also marked on the balancer) and also comparing each rotation with a 90 degree mark on the distributor, I then set up everything up cold with my intake at .018 and exhaust at .024 and then ran her up to normal operating temperature. Generally, the rockers seemed pretty quiet, although a couple of cylinders seem somewhat louder than others. I will drive her out for a awhile and go back in and re-check, perhaps making the lash tighter as Gkull's post recommends.
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Old 06-04-2010, 08:22 PM   #13
69autoXr
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Running less lash effectively increases the camshaft's duration, which may make the engine a bit finicky at low rpm. I set my lash to 18 and 24 last year for a track event as an experiment, it idled really choppy and took longer to warm up before it would idle. I'd stick with the factory lash for normal everyday use.
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Old 06-04-2010, 08:22 PM
 
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