Setting Valve Lash part 2 - Ford Mustang Forum
 
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post #1 of 8 (permalink) Old 06-18-2005
Acooljt
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Setting Valve Lash part 2

OK, I just want to know, how do I find TDC on every cylinder after 1? I mean, as you all know, there are no markings for those cylinders, so I'll have to more or less just get as close as I can?

And for those of you(I believe Putt in particular), who said to turn the pushrod until you feel tension and then a 1/2 turn from there, I never feel any tension, well, I do, but I can't tell the point between where it spins freely and when it has tension. So they way I did it(well, only piston 1 since my problem above), is I wiggled the rocker arm up and down on the pushrod and once there was no more clearance between the pushrod and rocker arm(no more wiggle up and down), I gave it a half turn from there. Is that alright?
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post #2 of 8 (permalink) Old 06-18-2005
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The half a turn from no clearance is correct. Just bump the engine over until the valve beside the one you are adjusting is on the way down.
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post #3 of 8 (permalink) Old 06-18-2005
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There's a method I've used for years that works really well. It may take a bit to explain it, but it's actually easier to do than it sounds. It will work on any engine with an even number of cylinders, but I'll use a 289/302 as the example.

First, I should probably make sure you're familiar with "valve overlap" and "rockover".

Valve overlap is the period near the end of the exhaust stroke that the intake valve is beginning to open while the exhaust valve is still closing. For a short period, both valves are open a small amount.

Rockover is the point at which both valves are open an equal amount and can be found by carefully observing the rocker arms as the crankshaft is "rocked" back and forth.

Okay, here we go... (assuming the valve covers are off...)

First, consider the firing order of the engine. In this case it's 15426378. Now, divide the firing order into two groups: 1542/6378 Beginning with cyl #1, bar the engine towards TDC compression stroke. Watch the rocker arms on cyl #6 (the first cylinder in the second group of the firing order). You should see the exhaust rocker closing on #6. When it's getting near to being closed, you will see the intake rocker starting to open. Continue slowly barring the engine over until the rockers are open an equal amount. At this point, #1 piston is at TDC. Adjust the valves on #1 cylinder.

Next cylinder in the firing order is #5 and the next to be adjusted. Bar the engine over again, this time watching the rockers on cyl #3 (the second cylinder in the second half of the firing order, and repeat the process used on cyl #1.

Then adjust cyl #4 while watching rockers of #7....then #2 w/#8....

See a pattern? After #2, continue barring to #6 and watch #1...

It's much easier to do after you do it the first time, and it works on all engine with an even number of cylinders. Just divide the firing order in half and "pair up" the cylinders.
Watch the "opposite cylinder" and you'll find TDC on any cylinder ever time. I believe it would probably be accurate to within 4or5 degrees....at least well close enough for setting valves.

I hope I explained it well enough....

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post #4 of 8 (permalink) Old 06-18-2005
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Is my way of wiggling the rocker arm sufficient to set the valve lash though? It is to my understanding that there should be zero lash(meaning zero clearance), so using that assumption, that's how I set #1.

Thanks for the help on finding TDC.
post #5 of 8 (permalink) Old 06-19-2005
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Quote:
Originally Posted by Acooljt
Is my way of wiggling the rocker arm sufficient to set the valve lash though? It is to my understanding that there should be zero lash(meaning zero clearance), so using that assumption, that's how I set #1.
That works just fine, Acooljt. You are actually setting a preload on the lifter, not zero lash. Zero lash is the point at which there is no wiggle left at the rocker.

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Originally Posted by Acooljt
Thanks for the help on finding TDC.
That explaination by wrenchman is very good, I need to remember that method!!

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post #6 of 8 (permalink) Old 06-20-2005
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Hey wrenchman, I'm thinkin your method is wrong. As I look at my motor right now, number 1 is at TDC and yet the number 6 lifters are not as you say they should be(both equally open). I know for a fact my timing set is on right, I've got pictures of the dots matching up and everything.
post #7 of 8 (permalink) Old 06-21-2005
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Could you offer an explanation or somethin?
post #8 of 8 (permalink) Old 06-23-2005
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Uh oh....it appears I may have jumped the gun on the previous post. Please pardon my oversight (it's been a heckuva week and I must've been suffering from "brain mush" when I wrote the post...)

Upon further review the method I described works on many engines, primarily in-line engines, and I would think on some vee-type engines depending on the crankshaft/firing order.

My most humble apologies. I will try to research this in more detail.

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