Question for Duke on adjusting valves

[Larry T.]

Duke,

I am setting the valve lash on my L72. I am following the procedure outlined in the paper authored by you and John Hinckley.

When I rotate the engine 90* from TDC after setting the first two valves (8E and 2I) I assume I rotate it in the direction the motor turns when running to adjust the next two valves. That is correct, is it not? Perhaps a stupid question, but I want to get it right the first time. While I am asking questions, do you still recommend .020/.022 on the settings for an L72? And since this is my first time adjusting solid lifters should the guage fit between the rocker arm and valve pretty tight?

Thanks,

Larry

[Larry T.]

Re: Question for Duke on adjusting valves

I guess Duke is out of pocket for now. Does anyone else affirmatively know the answer on this one?

[Richard G.]

Re: Question for Duke on adjusting valves

The adjustment sequence follows the firing order.
1-8-4-3-6-5-7-2
Thus the motor has to be rotated in the same as if running direction.
Rick

[Duke W.]

Re: Question for Duke on adjusting valves

You are correct. The sequence starting from TDC #1 end of compression stroke continues by rotating the engine in 90 degree increments in the normal running direction, which is clockwise when viewed from the front.

I still don't have enough reliable big block rocker ratio data to absolutely nail down the rocker ratio behavior, and until I do, I am sticking with the .020/.022" values that I have previously stated. I think several have used these settings with good results, including a quiet valvetrain.

If I ever do adjust these recommended values due to nailing the rocker ratio behavior, it will be very slight.

As far as how the feeler gage should "feel" I discussed that in the paper (on page 2), and I can't do any better, now.

BTW, make sure you have the latest revision, which is dated Sept '08 and is located here:

http://www.lbfun.com/warehouse/tech_...n/SBvlvadj.pdf

There are several sites that have earlier versions of this paper that are supeseded and obsolete.

This latest revision does not actually have recommended lash settings for SHP big blocks, and won't unless and until I can nail down big block rocker ratio behavior, but in the meantime, I have recommended the .020/.022" settings when the question comes up.

Duke

[Larry T.]

Re: Question for Duke on adjusting valves

Thanks for the info. I should have picked up on the rotation of the engine correlation with the firing order.

The document I have has one page. I wish I could remember where I got it so I could go back and look for a second page. In any event I just went with a snug fit of the feeler guage. It slides in and out, without forcing, with the rocker positioned as necessary for the most clearance. If this is not right I can redo them. I was waiting to hear back on the rotation question before closing everything up.

[Richard G.]

Re: Question for Duke on adjusting valves

Your posted method of feeler gauge is correct. It works excellent on new parts. Used sometimes have a slight wear pattern and the feeler gauge has a tendency to bridge this gap. I have a very narrow feeler gauge set I purchased for use on high mileage motors.
Rick

[Duke W.]

Re: Question for Duke on adjusting valves

Thanks for the info. I should have picked up on the rotation of the engine correlation with the firing order.

The document I have has one page. I wish I could remember where I got it so I could go back and look for a second page. In any event I just went with a snug fit of the feeler guage. It slides in and out, without forcing, with the rocker positioned as necessary for the most clearance. If this is not right I can redo them. I was waiting to hear back on the rotation question before closing everything up.

I suggest you (and others who might have the slightest interest) click on the link I provided for the latest revision of this two-page paper. Store it on your disk, and PRINT A COPY FOR YOUR PAPER FILES!

If I had a nickel for every guy who wrote me asking for a copy because his disk crashed....

Duke

[Michael F.]

Re: Question for Duke on adjusting valves

I can't open it, anyone got any ideas why??

[Duke W.]

Re: Question for Duke on adjusting valves

...don't know. I just clicked on the link, and it opened.

...copied and pasted again:

http://www.lbfun.com/warehouse/tech_...n/SBvlvadj.pdf

Duke

[Clem Z.]

Re: Question for Duke on adjusting valves

this adjustment will work on all cams stock and after market. rotate the engine in the normal rotation. when the exhaust pushrod on the cylindsr begins to move upward adjust the intake on that cylinder. when the intake pushrod moves all the way up and almost all the way down adjust the exhaust valve on that cylinder.

[Larry T.]

Re: Question for Duke on adjusting valves

Thanks for the help.

I followed the same process on all of the valves. The engine starts right up and runs well. However it continues to have the same noise it did that prompted me to adjust the valves in the first place. On the passengers side there is a clear audible clacking noise. The drivers side seems nice and quiet. I have often been told that is how it is, but why on one side. I have ruled out the noise coming from the heat riser by securing it in place temporarily. Any thoughts?

[Duke W.]

Re: Question for Duke on adjusting valves

If you followed the indexing procedure and adjusted the clearance to .020/.022", there should be no obvious valve noise. In fact, it might even fool some into thinking it has hydraulic lifters.

If you have one valve that is noisy, I'd suggest removing the rocker cover and starting the engine long enough to positively ID it. While the engine is running, eyeball the lift to determine if it matches the others. Then set the crackshaft to the proper indexing postion for adjusting that valve, check the clearance again and give everything a close inspection.

If nothing is obvious, remove the rocker nut, rocker arm, and pushrod for careful inspection. Reinstall the pushrod and place a dial indicator on the tip and rotate the engine as required to determine if it achieves full lift.

If the above inspections/tests reveal nothing rotate the engine to TDC, end of compression stroke for that cylinder, pressurize the cylinder such as you would for a leakdown test, remove the locks, retainer, and spring and check for excessive guide clearance and free vertical movement of the valve through its full lift value.

Duke

[Ken A.]

Re: Question for Duke on adjusting valves

this adjustment will work on all cams stock and after market. rotate the engine in the normal rotation. when the exhaust pushrod on the cylindsr begins to move upward adjust the intake on that cylinder. when the intake pushrod moves all the way up and almost all the way down adjust the exhaust valve on that cylinder.

This is the only CORRECT way to adjust valves on any engine with solid lifters. This method removes all the wear problems associated w/ components and no offense to the service manual method. Works on airplanes and any engine.

[Duke W.]

Re: Question for Duke on adjusting valves

If you plot out the OE cam lobes from the GM drawing data, as I have, including the 30-30 that is about 554 degrees duration from the beginning of the opening clearance ramp to the end of the closing clearance ramp, which leaves only about 168 degrees of rotation - less than half a crankshaft revolution - where the lifter is actually on the base circle, you will find that you can adjust the inlets at 90 deg. ATDC and the exhausts at 90 deg. BTDC.

That's how I came up with the procedure that is linked in a prior post.

I use a clipboard and write down the sequence starting with TDC number one and the valves to adjust there and the 7 subsequent positions/valves every 90 degrees.

Using a helper to read off the checklist and keep track of where I am I have been timed with a stopwatch doing the entire job (not including R&I of the valve covers and anything else that requires R&I) including rotating the engine as required and adjusting all the valves in less than five minutes, and a subsequent careful check showed they were all spot on.

Duke

[Joe C.]

Re: Question for Duke on adjusting valves

this adjustment will work on all cams stock and after market. rotate the engine in the normal rotation. when the exhaust pushrod on the cylindsr begins to move upward adjust the intake on that cylinder. when the intake pushrod moves all the way up and almost all the way down adjust the exhaust valve on that cylinder.

This is the only CORRECT way to adjust valves on any engine with solid lifters. This method removes all the wear problems associated w/ components and no offense to the service manual method. Works on airplanes and any engine.

This is the old tried and true method used by any engine builder worth his salt. Removes all of the guesswork and eliminates the need for pretentious technical papers.