TDC valve adjust question

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TDC valve adjust question

Post  GT300TD on August 22nd 2014, 9:58 am

Used the TDC 3 step method to adjust valves when I assembled the motor. Checked and re-checked the adjustment. This seems to be the easiest way for this beginner. Seemed to run pretty good with no problems, in that area  Rolling Eyes Cam is 22207 Crower Hyd (540in/ 541ex lift, 244in/ 251ex dur @ .050, 108* lobe sep. Advanced 2* at crank (9 point Cloyes gear) to bring down the power band. 11 to 1 compression 466.
Drove it Wed. and it started ticking, got louder, lucky I was only a few miles from the house. Limped home, pulled the valve covers and #7 exhaust rocker was laying between the springs. Adjust nut came off, noticed the poly lock was down in the adj. nut pretty far only about 3 or 4 threads left to go on the stud. Harland Sharp roller rockers.
Question: does this method work correctly with my cam and the 2* advance at the crank Question .
Thanks

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Re: TDC valve adjust question

Post  c.evans on August 22nd 2014, 6:24 pm

On that rocker that fell off, can you look at it and tell by the marks, which way you had the axle to the rocker turned?  Was the flat side up, or the rounded side up?  If the rounded side was up, it won't hold adjustment.
 
Charlie

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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 6:35 pm

A few questions; Did you back out all of the poly locks from the lock nuts prior to installing? You mentioned that you lashed the motor for start up, did you follow it up with a hot lash after initial start up? Did you verify that all pushrods were in the rocker arm cups prior to lashing if #7 was not in the cup but rather on the bottom of the rocker arm it would have held the rocker up and allowed you to lash it but when the motor was started it would have bent the pushrod or fallen back into the cup leaving the lock nut loose and vibrating off.

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Re: TDC valve adjust question

Post  nuclearcobra on August 22nd 2014, 8:48 pm

Also make sure the studs are long enough
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Re: TDC valve adjust question

Post  bbf-falcon on August 22nd 2014, 8:57 pm

nuclearcobra wrote:Also make sure the studs are long enough

X2,and what Charlie said.

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Re: TDC valve adjust question

Post  GT300TD on August 22nd 2014, 9:09 pm

c.evans wrote:On that rocker that fell off, can you look at it and tell by the marks, which way you had the axle to the rocker turned?  Was the flat side up, or the rounded side up?  If the rounded side was up, it won't hold adjustment.
 
Charlie

Yes, that was the first thing I checked and I barely had 1 1/2 threads showing on the stud when I turned it the wrong way. I measured how far down the poly lock was in the nut on the rest of the rocker arms. Then I screwed the poly lock the same distance down into the nut 'in question' and there was about 6 threads that would go onto the stud. Either the poly lock 'screwed itself' onto the nut or I mis-adjusted the darn thing in the first place  Rolling Eyes.
Thanks Charlie 

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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 9:09 pm

Question: does this method work correctly with my cam and the 2* advance at the crank Question .
Thanks[/quote]

My bad I talked to the incident as opposed to the question...The method will work, regardless of the advance (or retard), as long as the lash clearances. If the true TDC is wrong but you lash it at the same position every time you have established a base line just be CONSISTANT...when you push the envelope on the clearance (tight) just make sure you are using your correct baseline mark preferrably at the same temperature (operating eg:180*) If you are adjusting the timing on individual cylinders (power adders) be careful when you are pushing the envelope. The rules are the same as nitrous start safe analize and tighten (or lean) for improvement. The 3-stage method just speaks to the position of the valve not the experience of the adjuster.
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Re: TDC valve adjust question

Post  GT300TD on August 22nd 2014, 9:16 pm

FalconEh wrote:A few questions; Did you back out all of the poly locks from the lock nuts prior to installing?  You mentioned that you lashed the motor for start up, did you follow it up with a hot lash after initial start up? Did you verify that all pushrods were in the rocker arm cups prior to lashing if #7 was not in the cup but rather on the bottom of the rocker arm it would have held the rocker up and allowed you to lash it but when the motor was started it would have bent the pushrod or fallen back into the cup leaving the lock nut loose and vibrating off.



Backed out all the poly locks
All the pushrods were in the cups
Pushrod was ok
Please explain "hot lash"

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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 9:22 pm

Hot Lash meaning the clearance between the rocker arm tip and the valve when the engine is at operating temperature as opposed to a cold lash when the same measurement is taken when the engine is cold. The primary difference is the lifters have not bled down and the metals have all expanded as if they are in a real world situation, oil, metal, and clearance at operating temperature... TG for Mechanics gloves!
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Re: TDC valve adjust question

Post  GT300TD on August 22nd 2014, 9:28 pm

bbf-falcon wrote:
nuclearcobra wrote:Also make sure the studs are long enough

X2,and what Charlie said.

That is one of the things I was wondering to begin with, and after checking the distance on the other nuts there is about 6 threads that will tighten onto the stud. To begin with I tightened the poly locks with a box end wrench holding the nut and an allen wrench after I adjusted the lash 3/8 of a turn. I marked all the nuts to make sure about the 3/8 turn.
I did not use any thread locker, though.

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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 9:30 pm

Sometimes the opening on the rockers is clearanced enough on the fulcrum style rockers that if the axle does not drop to the bottom of the stud it wedges itself on a thread and uses dynamics to hold itself in place, in other words the axle has essentially lodged itself against a thread on the stud and did not seat at the bottom of the stud....same result the clearance is correct however the rocker arm is not properly seated until it starts, at which point the vibration (rumble) causes it to drop, also check the threads for a shiny spot on the stud likely on the exhaust side if you did not see it.
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Re: TDC valve adjust question

Post  GT300TD on August 22nd 2014, 9:30 pm

FalconEh wrote:Hot Lash meaning the clearance between the rocker arm tip and the valve when the engine is at operating temperature as opposed to a cold lash when the same measurement is taken when the engine is cold. The primary difference is the lifters have not bled down and the metals have all expanded as if they are in a real world situation, oil, metal, and clearance at operating temperature... TG for Mechanics gloves!

No  Embarassed 

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Re: TDC valve adjust question

Post  GT300TD on August 22nd 2014, 9:34 pm

FalconEh wrote:Sometimes the opening on the rockers is clearanced enough on the fulcrum style rockers that if the axle does not drop to the bottom of the stud it wedges itself on a thread and uses dynamics to hold itself in place, in other words the axle has essentially lodged itself against a thread on the stud and did not seat at the bottom of the stud....same result the clearance is correct however the rocker arm is not properly seated until it starts, at which point the vibration (rumble) causes it to drop, also check the threads for a shiny spot on the stud likely on the exhaust side if you did not see it.

HMMM, sure never thought of that.

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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 9:53 pm

Jesel valveterrain makes it easier but it comes with a price...
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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 9:55 pm

how do you normally use the lock when adjusting the valves...step by step
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Re: TDC valve adjust question

Post  GT300TD on August 22nd 2014, 10:36 pm

FalconEh wrote:how do you normally use the lock when adjusting the valves...step by step


Back the poly lock off to the top of the nut. Screw the nut down till the all the slack is taken out and the pushrod no longer moves up and down. I used to tighten the nut until the pushrod can no longer rotate but moving it up and down, very carefully, seems to be more accurate. Then I run the poly lock down til it touches the stud, check the up and down on the pushrod again. Tighten the nut 3/8 of a turn to preload the lifter then tighten the poly lock with an allen wrench while holding the nut in place with a box end wrench. I mark the nut in 3 places to make sure it stays in the same place.

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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 10:53 pm

The proceedure is good the only thing tat stands out to me is that the poly lock tightening is only the baseline, I always recheck the lash and then back off the the nut and the poly lock equally , tighten them together, and recheck, if it is not right then I turn in the lock to loosen the lash or turn out the lock to tighten the lash.....repetition will help the feel to be accurate .. but to me the ke is not tightening the lock ahead of the nut or the nut ahead of the lock ...lock them toghether!
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Re: TDC valve adjust question

Post  GT300TD on August 22nd 2014, 10:57 pm

FalconEh wrote:The proceedure is good the only thing tat stands out to me is that the poly lock tightening is only the baseline, I always recheck the lash and then back off the the nut and the poly lock equally , tighten them together, and recheck, if it is not right then I turn in the lock to loosen the lash or turn out the lock to tighten the lash.....repetition will help the feel to be accurate .. but to me the ke is not tightening the lock ahead of the nut or the nut ahead of the lock ...lock them toghether!

OK! Will be putting the Gal back on the road Monday.
Thanks a Bunch...everyone! Very Happy
Would you use a medium thread locker?

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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 11:00 pm

The valve terrrain is probably real soft (loose) but once you are done letting the Big dog eat you are going to have a blast...Enjoy let us know how the next shake down goes!
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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 11:02 pm

IMO no thread locker is required, if you lock them toghether, but I would ask for ADMIN interjection if they do not agree
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Re: TDC valve adjust question

Post  GT300TD on August 22nd 2014, 11:06 pm

FalconEh wrote:IMO no thread locker is required, if you lock them toghether, but I would ask for ADMIN interjection if they do not agree

Thanks again  Very Happy 

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Re: TDC valve adjust question

Post  FalconEh on August 22nd 2014, 11:13 pm

I can't offer much but I offer what I can ... once you get her out we can talk about int vs exh timing to better the intake or EXHAUST flow of the heads as the NOS learning curve taught me the difference... lol! 
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Re: TDC valve adjust question

Post  gt350hr on August 23rd 2014, 10:31 am

NO thread locker, big mistake. That is why you have an allen set screw. Sometimes the top of the stud is irregular enough that the set screw doesn't get a good "bite". Careful tightening is the key. Now you are keen to the potential problem and will naturally be more cautious.

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Re: TDC valve adjust question

Post  GT300TD on August 24th 2014, 8:20 am

gt350hr wrote:  NO thread locker, big mistake. That is why you have an allen set screw. Sometimes the top of the stud is irregular enough that the set screw doesn't get a good "bite". Careful tightening is the key. Now you are keen to the potential problem and will naturally be more cautious.


O.K.  I sure don't want to make any more mistakes...especially a BIG one  Smile 
Thanks

edit...ya think I ought to go 1/2 turn instead of 3/8 to set preload  Question . It's a street car.

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Re: TDC valve adjust question

Post  FalconEh on August 24th 2014, 10:39 am



edit...ya think I ought to go 1/2 turn instead of 3/8 to set preload  Question . It's a street car.[/quote]

Here you have to be careful, you have a safe baseline... stick with it until you are more comfortable setting them. These valve adjustments affect the entire valve terrain many factors including pushrod length, lifter travel etc. must be taken into consideration. If you are setting preload by partial turn of preload you are using hydraulic lifters and although they are forgiving you do not want to tighten too much and bottom out the lifter causing damage to pushrods/lifters etc. When it comes to valve lash do not swing for the fences, adjust in small increments, consistently and equally paying close attention what the motor is doing (especially at upper rpm). Just remember that lash changes are usually made in .001-.002 increments when adjusting solid liffters. You can find more power in a tighter lash but as you say it is a street car and the reward may not be worth the risk.
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