tappet adjuster thread size/pitch

[Dartgame]

Opened up the can of proverbial worms. I started adjusting the valves on my 218 which has about 40K original miles on it. I noticed that a few of the valves appeared to have no lash and unfortunately I adjusted them. Afterwards I thought about it after running the engine and hearing a few noisy tappets, that these must have cupped the adjuster disguising the open lash. So I need a way to get these few back to some where close to the correct lash I need a method to estimate that range. 

 

If I know the threads per inch on the adjuster I should be able to get the lash someplace half way close. For instance if they are 32 threads per inch, 1 divided by 32 = 0.03125 inches, thus to get .010 to .014 - close the lash to zero and back off the adjuster by about 1/3 of a turn.

 

Anybody know the thread size and pitch ? Either that or a method to adjust these cupped adjusters ? I am against running the engine hot and adjusting since there is no way to check the clearance, but could be done by ear I suppose.

[Jerry Roberts]

Do it by ear . Loosen them up until you hear CLACK - CLACK - CLACK , and then tighten until you hear click - click - click .

[Dartgame]

Thanks, I'd like to get them closer before running -

 

Anybody else ?

[Matt Wilson]

How about trying what's called a dial test indicator.  It's not the same as a dial indicator, but similar, but has a probe that extends sideways from the tool so it could probably reach into the tappet area to get a reading of the valve clearance.  You could place the end of that probe onto the tappet and move the tappet up and down by hand (when the tappet is on the base circle of the cam, not on the high part of the lobe, of course) and see what the clearance is.  Then adjust the tappet screw till you have the indicator reading you are looking for.  Some manuals say a decent initial tappet setting for a cold engine is 0.014" (I believe this is for intake and exhaust).  This would get you close and then you'd have to run the engine to warm it up, shut it down to set up the dial test indicator on the first tappet you want to check, adjust it while the engine is still hot (not running), then run the engine some more and move the dial test indicator to the next tappet and so on.

[vintage6t]

For the same reason, I've used the TPI method to adjust the valve lash on a Ford Y block. It works well.

 

One thing you can try in terms of approximation is this:

1. Close the adjuster on to a valve using any given feeler gauge. This is reading 1.

2. Back off the adjuster one full turn, 360 degrees.

3. Measure the resulting lash with a feeler gauge. This is reading 2.

4. Subtract reading 1 from reading 2. This will give you how much lash you get in 360 degrees. Now you know how much the lash changes in 1/8, 1/4, 1/2 turn and so on.

 

 

[Dartgame]

Excellent Ideas about this situation. Will keep this in mind.

 

Anyway, I fiddled around with the lash adjustment and came to a conclusion that the few lifter adjustment pads I thought were cupped - are indeed NOT cupped. Keep in mind this car has 40K on it and never had the valves adjusted from what I can tell. What I believe is that over the years with the valves sinking into the block a little, it caused next to no lash on a few isolated valves. 

 

Adjusting the valves - So what I did was use the speedy valve adjustment chart where you use TDC for 1 and 6 and adjust the valves as indicated in the chart. Interestingly what I found was several valves ended up being looser adjusted this way from 2-4 thousands larger using 10 and 12 thou for intake and exhaust respectively. So what I did - for instance was bring #3 intake up to full lift (approximately by eye) and then checked and adjusted #3 exhaust. I went around all 12 valves this way and located several that needed this fine tuning. All done cold. Started her up and voila running like a sewing machine. I suspect the speedy chart doesnt account for the cams ramp in a few cases and thus gives the wrong lash reading. I ran the motor and fiddled with one of the exhausts that was not spinning. I tightened it a little so it was reading about 9 thou hot, and it started spinning some anyway. The rest looked fine.

 

I was hesitant about messing with this stuff hot, but it was not as bad as I had imagined. What I am going to do is get some long feeler gauges ranging from .009 to .014 so as to avoid touching the hot exhaust manifold when running, adjust as needed, and close the book on this learning chapter.

[Los_Control]

I'm not really sure what you want ..... the valves are adjusted with a feeler gauge & not thread pitch.

 

I'm calling @keithb7 out because they made a excellent video on adjusting valves ..... I can not find the video now.

I do remember watching it ...... I just cant find it on Keith channel to share it.

 

The book gives you Hot & cold valve lash, & you set it with a feeler gauge, not by thread pitch.

The idea of setting it by thread pitch is so far out in left field nobody knows how to reply.

 

Ask how to set valves you will get answers ..... ask how to set them with thread pitch, people will take a wide berth stepping around you.

[Dartgame]

I watched Keiths videos, and other posts as well. Don't want or need anything further, just finishing the post with my solution, please read my last post above. I already have it handled. I know how to use feeler gauges.

[Sam Buchanan]

11 hours ago, vintage6t said:

For the same reason, I've used the TPI method to adjust the valve lash on a Ford Y block. It works well.

 

One thing you can try in terms of approximation is this:

1. Close the adjuster on to a valve using any given feeler gauge. This is reading 1.

2. Back off the adjuster one full turn, 360 degrees.

3. Measure the resulting lash with a feeler gauge. This is reading 2.

4. Subtract reading 1 from reading 2. This will give you how much lash you get in 360 degrees. Now you know how much the lash changes in 1/8, 1/4, 1/2 turn and so on.

 

 

 

I like this....clever. I suspect some of the rocker arms on my TR6 may be slightly dished, may try this next time as a reality check.

Edited June 7, 2023 by Sam Buchanan

[keithb7]

I read the original post. I didn’t have time to give it much thought. I was thinking, maybe the tappets are really cupped? I didn’t reply thinking maybe I’m not educated on cupped tappets.  I think you got it right with the lobe ramps. I feel that one needs to have the piston at TDC so you can positively confirm 100% that the tappets can wiggle up and down. Then you know without a doubt you are not on a lobe ramp. Neither intake nor exhaust ramps. Then you’ll get them set right. 
 

Hot or cold, I’ve done ‘em both ways with good results. Hot, then you’re down in the heat and crankcase gasses. By the time you’re done you look like a chimney sweeper in 1902. Your lungs may look similar. Lol. 
 

I read somewhere about the siamese design of our blocks. Coolant flows around the outer walls of each pair of cylinders. Not through the centre of each pair. I studied my blocks. Makes sense. They say due to this design the valves don’t all run at the same temps. Makes logical sense to me. It takes a good 15-20 mins of driving under load to get the entire block and all it’s related parts up to operating temperature. When all is hot, when we set the lash gap, we get it right.  In theory a hot valve with less than efficient water cooling could be .001 longer than the next valve. In theory…

 

A car with 40,000 miles and no valve set? Curious if you have you done a wet/dry compression test? Tight, hot exhaust valves break down. They open sooner and close later. The longer the valve is off its seat the hotter it runs. Hot enough to break down iron and steel. Like a oxy/acet cutting torch on your exhaust valves. That’s pretty much exactly what’s happening. 

 

 

 

Edited June 8, 2023 by keithb7

[Sniper]

17 hours ago, Dartgame said:

What I believe is that over the years with the valves sinking into the block a little

 

Doubtful as they have hardened seats from the factory

[Dodgeb4ya]

Another easy way to accurately check tappet clearance with dished tappet adjuster screws .