Valve setting problems...HELP!! - Team Camaro Tech
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post #1 of 8 (permalink) Old Sep 1st, 04, 06:18 PM Thread Starter
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Gary
 
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I finally got my 427 to broken in. (Lunati
hydraulic cam, 290/290 duration, [email protected], .544 lift) But the only way I could get it to start it was to tighten the intake adjustment nut to Zero lash, using the EO/IC method, and then loosen it 1 turn. (Boy, were they loose....but I got maximum compression of 110 psi there.

After break in, I reset the valves to zero lash + 1/4 turn, again using he EO/IC method, but it will not start. I don't see how this makes a difference, but I'm using Comp roller tip rockers.

I don't think I am overtightening, as I ran the motor for a minute before resetting, to make sure the lifters were pumped, and was very, very careful about stopping when I felt the slightest drag while spinning the push rods.

Why would I get higher compression with loose valves, which would make the intake open later, and close sooner, reducing compression?

What is the problem?
What can I do to fix it?

Thanks in advance for the help.
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post #2 of 8 (permalink) Old Sep 2nd, 04, 05:48 AM
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Loosening the lash should raise the cranking pressure. Did you degree the cam?
When you adjust the lifters, don't spin the pushrods, they can be pretty tight and still spin. Loosen the rocker arm until you can move the pushrod up and down. Slowly tighten the adjustment until the slack is taken up, where the pushrod just stops going up and down easily, then another 1/4 to 1/2 turn.

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post #3 of 8 (permalink) Old Sep 2nd, 04, 06:04 AM
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You should have more cranking compression than 110 lbs. It really sounds like you are going way past zero lash.


The spin the pushrod method of finding zero lash really requires an experienced touch. Try bouncing (if there is any lash the pushrod will bounce or rattle as you jiggle it up and down) the pushrod up and down between the lifter and rocker and tighten the adjustment until the pushrod just stops bouncing. Loosen it just a touch to get it to bounce and then tighten just enough to take the bounce away. From there go 1/4 - 1/2 turn to add the proper preload.

EO/IC is the most accurate but try this, pull the #1 plug (or all to make turning the engine over easier) and turn the engine over by hand and watch the dampner to see when it's about 90 degs away from TDC. Place your thumb or finger in the #1 plug hole and turn the engine (assuming the timing marks are correct) over until the mark on the dampner is at TDC. If you felt the compression push your thumb out of the hole you have #1 at TDC. Caution: If you have the rockers so tight that the valves are being held open when they should be closed you may not feel any compression as #1 comes to TDC.

Both valves should be closed and the lifters should be on the base circle enough that you can adjust the lash and preload on both rockers. If you didn't feel any compression on #1 then go over to #6 and adjust there instead of #1.

From there mark your dampner every 90 degs and turn the engine to the next mark. Follow the firing order 1-8-4-3-6-5-7-2 every 90 degs. If you started on #6 go to 5 next...

...Dennis

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post #4 of 8 (permalink) Old Sep 2nd, 04, 06:48 AM
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How did it run when you had them loose? It might be that the outer ring of the dampner has slipped and you might not be getting exact readings.
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post #5 of 8 (permalink) Old Sep 3rd, 04, 03:27 AM Thread Starter
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Gary
 
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By eye, the timing mark lines up with the balancer, but I degreed the cam, and found it to be 1-2 degrees retarded. (I did not have a stop, so I used a magnetic dial indicator)
I have used 3 methods for finding zero lash.
1. rattling the push rod up and down.
2. twisting the rod
3. feeler gauge
All were within 1-2 clicks of each other...certainly closer than the difference between 1/4 to 1/2 turn preload.

Dennis, I know it sounds like I'm going way past zero lash, but after setting them half a dozen times, using different methods, and getting virtually the same results, I can't believe that's the problem.

BTW, I squirted oil in one cyl and rechecked the compression....it did not change. I was dilligent about staggering the rings, and making sure the dot was up when I put the motor together.

Signed,
Baffled and Frustrated
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post #6 of 8 (permalink) Old Sep 3rd, 04, 05:15 AM
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What rocker arms are you using? Have you made sure that the rocker body is not hitting the spring retainer? Pretty common with some roller rocker/spring combos. If they are they will start to open the valve even though the pushrod is still loose. By the time you have the pushrod slack taken out you can be hanging a valve open.

It's got to be something like this to affect the compression. And if adjusting them correctly drops the compression then valves have to be partially open.

Jody


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post #7 of 8 (permalink) Old Sep 3rd, 04, 11:53 AM Thread Starter
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I just finished reading a post about the dots on the timing gear. I definately set mine dot-to-dot, rather that both pointing straight up. However, early in the process of trying to start the motor (at the time, thinking it was an ignition problem), I reversed the distributor 180 degrees thinking that might be why it would not start. Well, it was like the 4th of July fireworks show coming from the carb. So I put it back.

I thought I was careful about setting the timing chain, but what if I actually set it up one or two teeth off?

Would that make the engine want to run only with loose push rods?

Short of removing the balancer, and timing cover, is there a way to check the alignment? God, I hope so....you have no idea how hard it was to install the balancer!!
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post #8 of 8 (permalink) Old Sep 4th, 04, 04:09 PM
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You can check the cam alignment with it together, but you'll have to have the cam card, and a degree wheel kit with a screw in the plug hole stop to help find true tdc.

And I know it's messy, but the only way to set hydraulic lifters is WITH THE ENGINE RUNNING.

The oil will clean up, honest....





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