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Old 06-26-2013, 09:06 PM
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valve lash too tight

So this might be a tad long....
My little S10, 383
Smoking at idle, and really smoking when on it hard. Thought it was oil, then after a better look realized it was fuel. Weirder still, it didn't seem like black or grey smoke, but was eye watering rich, and smelled rich. Thought it was Carb related. It was a summit 750 VC Carb. Virtually brand new. Swapped it out tonight for a quick fuel 650 DP, went for a drive. Still smoking. The truck always had a loud valvetrain, like real loud, then after abusing it pretty good tonight, I thought I heard a valve train clatter. Noise wasn't there by the time I got it home. Grabbed the vacuum guage to set up Carb. In gear, less then 5" of vacuum. And fluctuates....that seemed way low, even for this cam, 234/244 @.050
Hmmmm.......decided to check lash. Old fashioned method if backing them off till they clatter, then tighten just till the noise stops, then half to 3/4 of a turn and tighten the locks. Well when I went to back them off, some took 5-6 full turns until it clattered, some as many as 8 full turns.!!!
Idle cleaned up (smoother) and now show 9" of vacuum in gear, 14 in park. Also wentnfrom 20psi oil pressure in gear, to 33psi, valve train much quieter. No idea if it smokes anymore cause by this time its dark. What i do know is its fast, real real fast. Feels like I picked up 100 friggen HP. By far the fastest car I have owned. Love the quick fuel Carb, its dead smooth, and has the most amazing response. The only change I made was going from a 6.5 to a 4.5PV.
Could to tight lash really have made that big a difference? Long term damage?
How it didn't hurt the cam, or bend something I don't know.

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Old 06-27-2013, 03:06 AM
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What's the question?



Duke
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Old 06-27-2013, 04:19 AM
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What's the question?



Duke
Lol, sorry Duke, was tired and long winded.
What's a normal symptom of valve lash being to tight, and long term effects. (Damage etc)
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Old 06-27-2013, 05:24 AM
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toooo tight

wiping out a cam is the mostly likely result. u'll find out soon.. u may get lucky too.. doesn't seem like u bent anything.. i just wonder who did the adj the first place ??? that was an oooops for sure..
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Old 06-27-2013, 08:40 AM
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Good thing you found they was to tight,, It will run better when they are set right... To tight and you will wipe out a cam in no time.. Hope you found it in time... I would run a compression test to see how the compression is...
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Old 06-27-2013, 09:45 AM
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Quote:
Originally Posted by bygddy View Post
So this might be a tad long....
My little S10, 383
Smoking at idle, and really smoking when on it hard. Thought it was oil, then after a better look realized it was fuel. Weirder still, it didn't seem like black or grey smoke, but was eye watering rich, and smelled rich. Thought it was Carb related. It was a summit 750 VC Carb. Virtually brand new. Swapped it out tonight for a quick fuel 650 DP, went for a drive. Still smoking. The truck always had a loud valvetrain, like real loud, then after abusing it pretty good tonight, I thought I heard a valve train clatter. Noise wasn't there by the time I got it home. Grabbed the vacuum guage to set up Carb. In gear, less then 5" of vacuum. And fluctuates....that seemed way low, even for this cam, 234/244 @.050
Hmmmm.......decided to check lash. Old fashioned method if backing them off till they clatter, then tighten just till the noise stops, then half to 3/4 of a turn and tighten the locks. Well when I went to back them off, some took 5-6 full turns until it clattered, some as many as 8 full turns.!!!
Idle cleaned up (smoother) and now show 9" of vacuum in gear, 14 in park. Also wentnfrom 20psi oil pressure in gear, to 33psi, valve train much quieter. No idea if it smokes anymore cause by this time its dark. What i do know is its fast, real real fast. Feels like I picked up 100 friggen HP. By far the fastest car I have owned. Love the quick fuel Carb, its dead smooth, and has the most amazing response. The only change I made was going from a 6.5 to a 4.5PV.
Could to tight lash really have made that big a difference? Long term damage?
How it didn't hurt the cam, or bend something I don't know.
If you lash them so tight that the plunger seats, after that any additional tightening opens the valve. This will loose compression and power, the engine will have low vacuum because the valves (some to all) are not seating. The risk besides valves meeting pistons is heat related as the valve needs to seat to cool itself, burnt valves and head seats can be a result if this is pushed too far for too long.

Bogie
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Old 06-27-2013, 03:21 PM
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Here's the tutorial for doing correct adjustment on SBC/BBC.....
http://www.crankshaftcoalition.com/w...stment_SBC/BBC
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Old 06-27-2013, 03:41 PM
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Quote:
Originally Posted by bygddy View Post
Lol, sorry Duke, was tired and long winded.
What's a normal symptom of valve lash being to tight, and long term effects. (Damage etc)
Sorry mate, your question WAS clear.

I replyed my post to the wrong thread,,,,, too much single malt whiskey .. Lol!

The replys from the other members seem valid to me..

Hope it's all ok !



Duke
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Old 06-27-2013, 04:46 PM
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The method of valve adjustment in the pits:

Mark the harmonic damper in four locations, equally spaced, starting with #1 cylinder. The marks do not have to be dead-nuts exact using a degree wheel. Eye-balling the marks is close enough.

After marking the damper, turn the engine by hand with a long breaker-bar until #1 is at TDC on the compression stroke.

Set intake and exhaust lifter pre load on #1.
Turn to next mark, set intake and exhaust pre load on #8
Turn to next mark, set intake and exhaust pre load on #4
Turn to next mark, set intake and exhaust pre load on #3
Turn to next mark, set intake and exhaust pre load on #6
Continue turning CW to each mark and set the intake and exhaust valve lifter pre load according to the firing order: 1 8 4 3 6 5 7 2 until all are set. This method guarantees the lifter is on the base circle of the cam lobe when you adjust the pre load. You can also use this method with solid lifters.

It will take two revolutions of the crank to set the lifter pre-load on all eight cylinders.
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Old 06-27-2013, 05:06 PM
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I set them the old fashioned way, cut open valve cover, back them off till they clatter, tighten just just till they stop, then go half turn.
I didn't set them, the PO did. It ran like that for approximately 800miles or so. Now has steady 9" of vacuum at idle in gear.
Just went for a run now in daylight, no smoke, pulls hard to 6200 and has lots and lots of power. And the valvetrain is much quieter, which seems the opposite of what it should be but I'm not complaining. I guess time will tell if the cam's hurt. For now it pulls real real hard. Next thing to address is a real rear end instead of the mini spool 7.5 it has now. And then traction. Was going to hit the strip this Fri but
A: its supposed to rain
B: it doesn't have a prayer of hooking so its kinda pointless.
I hate being that guy with a spool, a lumpy cam, loud exhaust, fuel cell, and then running 15's sideways till half track.
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Old 06-27-2013, 05:14 PM
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Quote:
Originally Posted by bygddy View Post
I set them the old fashioned way, cut open valve cover, back them off till they clatter, tighten just just till they stop, then go half turn.
Best way to set them if you ask me...
I stay in between a 1/4 to 1/2 turn..Work's everytime...
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Old 06-30-2013, 01:41 PM
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This is the method I use. Simple and foolproof, which is a big help for me...



Quote:
Originally Posted by MouseFink View Post
The method of valve adjustment in the pits:

Mark the harmonic damper in four locations, equally spaced, starting with #1 cylinder. The marks do not have to be dead-nuts exact using a degree wheel. Eye-balling the marks is close enough.

After marking the damper, turn the engine by hand with a long breaker-bar until #1 is at TDC on the compression stroke.

Set intake and exhaust lifter pre load on #1.
Turn to next mark, set intake and exhaust pre load on #8
Turn to next mark, set intake and exhaust pre load on #4
Turn to next mark, set intake and exhaust pre load on #3
Turn to next mark, set intake and exhaust pre load on #6
Continue turning CW to each mark and set the intake and exhaust valve lifter pre load according to the firing order: 1 8 4 3 6 5 7 2 until all are set. This method guarantees the lifter is on the base circle of the cam lobe when you adjust the pre load. You can also use this method with solid lifters.

It will take two revolutions of the crank to set the lifter pre-load on all eight cylinders.
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Old 07-09-2013, 11:31 PM
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last time I over-lashed my valves, the car idled nicely.. but couldn't make enough power to climb the trailer ramps to get it home...

i learned the hard way that 'twirling' the rods is not an accurate (for me) way to find the zero lash point.

I usually jiggle the push rod up and down while tightening the rocker, once I can't move it up and down and more i put a 1/4 turn in it... then re-set them with it running. (I cut a window in an old chrome valve cover, that way i don't spray oil every where)

i didn't read the link TechInspector posted, but I found another site that suggested the jiggle method... once you are down to almost no up and down play then twirl, and as soon as you feel the slightest change in resistance to twirling..stop tightening.

i wiped out two camshafts before I figured out I wasn't setting the lash right.. for a long time I just refused to set lash w/o the engine running..
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