Valve adjustment woes

rdharper02 · Mar 12, 2011

Went to adjust my valves today on the white gt. Currently, it has a custom cam, hyd roller lifters, AFRs, and 1.6 RR arms. I started the adjustment sequence today and got to the third set when I noticed the number 1 cylinder intake valve (first one adjusted) was loose again.

Let me know if I’m doing something wrong here.

I started with taking the motor to TDC and rotated until I noticed the exhaust valve starting to open. I adjusted it until the push rod could no longer spin then tightened it a quarter turn, bottomed out the lock and then adjusted another 1/4 to 1/8th a turn as it fully locks out.
-Next I rotate the motor 180 degrees and do the same for the exhaust valve.

Am I wrong here, or do I have greater problems?

gt40_2003wes · Mar 12, 2011

when u adjust the exhaust valve you turn it until the intake valve is almost completely closed then hand tighten to no slack and 1/2 turn.

90 lx convert · Mar 12, 2011

All adjustments should be made on the bottom of the lobe of the cam. So if the intake is the one you're adjusting and it has stopped moving and the exhaust has started to move then it should be OK. One thing to remember once you crank the motor over by hand the pressure on the lifter has bled off. Without that pressure the only thing left is the spring in the lifter and that may not be enough to push up the rocker. The best way to do this is to back off the adjuster so the plunger in the lifter can come up to the stop. That way you know there is no preload on the lifter plunger. Now make the adjustment while turning the pushrod. To get an accurate preload on the lifter a dial indicator is best. I've done alot of cars at 1/4 turn and found they were too noisy and had to give it another 1/4. Usually I see how much turn gives the right preload with a dial indicator on one valve and then just duplicate that amount of turn on all the others. Mike

Rick 91GT · Mar 13, 2011

Mike is correct.... it also depends on the profile of the lobe on your cam.

Here is the process I have been using for years from Ed @ FTI.

1. Remove the valve covers, and pick a cylinder you are going to set the pre-load on. Only do one cylinder at a time.

2. Rotate the engine in its normal direction of rotation (clockwise) and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm.

3. To adjust, back off the intake rocker arm adjusting nut and remove any tension from the push rod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the push rod seat up against the retaining lock, if you give it time to do so.

4. Twist the intake push rod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the push rod, you are at "Zero Lash". Turn the adjusting nut down one half to three-quarters of a turn from that point for street applications. Use 1/8 to 1/4 turn for race applications. Lock the adjuster into position. The intake is now adjusted properly.

5. Continue to turn the engine, watching that same intake valve/rocker you just set. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.

rdharper02 · Mar 13, 2011

I appreciate all the feedback. I am going back into it today and starting from scratch. I think what has happend is that the lifter bled down, leaving extra side to side play in the rocker. I'm going to back them all off and work on the "spin' method. Unfortunately, the cars been setting there for a few weeks, so I'm going to do my best job at finding the start of resitance for each pushrod. Never thought I would say this, but this is where I regret not having a carb as i would have adjusted them out at idle. No worries< hopefully there will be enough time today and I'll know how it goes.

-Rick, can you get a deal on pushrods...lol. Do need to catch up with you about some springs for a Gt40p set-up. Thanks again for the help.

88-378 · Mar 14, 2011

Rick 91GT said:
Mike is correct.... it also depends on the profile of the lobe on your cam.

Here is the process I have been using for years from Ed @ FTI.

1. Remove the valve covers, and pick a cylinder you are going to set the pre-load on. Only do one cylinder at a time.

2. Rotate the engine in its normal direction of rotation (clockwise) and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm.

3. To adjust, back off the intake rocker arm adjusting nut and remove any tension from the push rod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the push rod seat up against the retaining lock, if you give it time to do so.

4. Twist the intake push rod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the push rod, you are at "Zero Lash". Turn the adjusting nut down one half to three-quarters of a turn from that point for street applications. Use 1/8 to 1/4 turn for race applications. Lock the adjuster into position. The intake is now adjusted properly.

5. Continue to turn the engine, watching that same intake valve/rocker you just set. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.

This is what I use.

Valve adjustment woes

rdharper02

like kicking myself in the junk

gt40_2003wes

I did sound a wee bit gay there.

90 lx convert

Stanger

Rick 91GT

Mustang Master

rdharper02

like kicking myself in the junk

88-378

Member

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Valve adjustment woes

rdharper02

like kicking myself in the junk

gt40_2003wes

I did sound a wee bit gay there.

90 lx convert

Stanger

Rick 91GT

Mustang Master

rdharper02

like kicking myself in the junk

88-378

Member

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