How To Set And Adjust Valve Lash Like A Pro - Dragzine

Setting and adjusting the valve lash is often overlooked as a simplistic and unsophisticated task for proper engine maintenance, yet much can be gained by paying attention to valve lash. Good initial set up and keeping a close eye on the valve lash can alert you to a problem before it leads to a...

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Copied from the linked article- "Lightly turn the pushrod with your fingers as you tighten the adjusting nut, and you should feel a point where there is a little resistance (this is called Zero Lash)."

Everything I have read says this is NOT the way to do it. You cannot feel even a slight bit of resistance spinning the pushrod with your fingers. You move the pushrod up and down while tightening the nut until there is no movement and then you are at Zero Lash.

 

My engine has Rhodes hi rev hydraulic flat tappet lifters and a TRW copy of a 289 hi po cam. { Per Rhodes instructions} I always turned the engine until both rockers were loose {I & E}. Tightened them without much preload on the lifters. I Started the engine with the valve covers off one side at a time. I would loosen each rocker arm until it tapped and then tightened it down until it stopped. I also redid this after the engine was hot which didn't make much of a difference with the hydraulic lifters. Then I tightened the lock nut down. After breaking in if I heard any tapping I would readjust. Wasn't usually necessary. I did invest in reusable rubber valve cover gaskets. The best way to do this is with an extra valve cover with the top cut out to help keep oil from going everywhere. It worked for me but my valve train was adjustable with screw in studs and guide plates.

 

Ah, another valve adjustment thread.

Adjust hydraulic valves with the engine cold.

Do this, and it will run smoothly, and likely with more power:

Disconnect the coil + wire.
Attach a bump switch to the solenoid, or just use a screwdriver.

Turn the engine so the #1 intake valve is fully opened. Loosen the exhaust valve until you can move the #1 exhaust valve pushrod up and down (NOT spinning).
Tighten this valve until no up and down movement can be felt, then tighten an additional 3/4 turn.

Note: Spinning the pushrod can cause a false adjustment, as a slowly collapsing lifter can allow the pushrod to spin freely, thus throwing off the base line of your adjustment.

Turn the engine so the #1 exhaust valve is fully opened. Loosen the intake valve until you can move the #1 intake valve pushrod up and down (again, NOT spinning).
Tighten this valve until no up and down movement can be felt, then tighten an additional 3/4 turn.

Repeat for the other 7 cylinders.

I did this on a friend’s engine that had been adjusted when built, then driven for several years. It was running OK, but not great, you could hear some valve noise. After doing the above, it did not seem to be much better immediately after adjustment, mostly because the lifters had been varnished into position by years of driving. Coupla miles around the block, though, and it was a whole 'nother engine.

Adjusting mechanical valves.

I drove a 289HP daily for 20 years, and every 6000 miles I adjusted the valves, which took less than an hour.

Adjusted properly, they aren't noisy, either, just a high-pitched singing sound.

Factory spec for the 289HP C3OZ-6250-C cam is .022" cold, .018" hot.

The procedure in the Manual is a bit complicated, and involves marking the balancer at 90° points, and then you follow some weird pattern, like I1, E4, I6, E2, or some complex crap. Takes an hour just to figure out what they want you to do.

Do this instead-

Run the engine until it is a full operating temperature. Disconnect the coil + wire, and remove one valve cover.

Attach a bump switch to the solenoid, or just use a screwdriver.

Bump the starter until the second valve on the #1 cylinder is all the way open. This means the one closest to the radiator is closed, on the base circle of the cam lobe. Adjust the valve to .018".

Bump the starter until that valve is fully open, and adjust the second valve.

Continue to adjust the valves in pairs until the RH head is adjusted, and install the valve cover.

Repeat the process on the LH side of the engine. I like to start and run the engine to be sure it is still fully warmed up.

Remove the LH valve cover, and adjust the LH valves to .018".

Very quick, and very accurate.

If the engine has just been assembled, do the procedure cold, at .022”. Then warm up the engine and do it hot.

 

A rocker arm whose associated valve is seated will feel loose (meaning you can actually feel slight movement in the rocker) compared to a lifter whose associated valve is lifted. If you adjusted correctly and added 3/4 turn after true zero lash you should be fine.

 

No it doesn't. Point being, either method will be same end result to a seasoned mechanic, or a nightmare to a novice. That said, I've seen many (help) threads on valve adjustment procedures here that verify exactly what I said whether spin or play method. The method isn't the problem and to tell someone they're doing it wrong is, well, wrong. And I challenge you to find up/down 0 lash on an unprimed lifter and not be able to collapse it further with very little effort..............with thumb and index....Not at all arguing. Just saying.

 

I've tried every method possible, and I always come back to ole reliable; just past TDC for each cylinder, tighten both rockers 1/2-3/4 turn past 0 lash. Ive found this to be the MOST consistent setting for all cylinders without bouncing around rocker to rocker.

 

Hello all, looking for some guidance. I adjusted the lash on my rockers using Tom Monroes SBF guidance. Seemed to go well as I was following the process, it is very strait forward, you adjust the lash for the indicated rockers based on three points on the harmonic balancer being placed on the pointer.

Anyhow, after adjusting, I placed the engine back to TDC and many of the rockers are pretty loose. Is this correct? They were adjusted for zero lash plus 3/4 turn at the appropriate position as indicated below. I would have expected that after the lash is adjusted on every rocker that they would all be fairly snug no matter the engine position when complete. Any guidance or knowledge would be appreciated here.
Thanks,
View attachment 870402

To answer your original question”…placed the engine back to TDC and many of the rockers are pretty loose. Is this correct?” The answer is yes, especially if the lifters are new and have never been pressure lubed by the oil pump. The spring holding the lifter seat in place at the top of the lifter isn’t all that strong. The lifter, when engine running and under pressure lube, hydraulically holds the plunger/seat up.

My fear, as others here have pointed out, is having the lifter plunger depressed because you’ve over turned the rocker adjuster, and now you hold a valve open. I would rather err to the lose side and re tighten any noisy lifters. And not burn a valve or kiss a piston.

JMO.

 

When in doubt, check it the way Ford instructs.... place the lifter on the base circle, collapse the lifter and measure the lash at the tip.

 

I found this years ago from a race engine builder. Made a few changes to my specific needs. Works every time.

 

That’s the way to do it IMO. Once you do it once or twice and get the hang of it, you can run the valves in ten minutes.

 

My method. Hasn't failed me.....yet.