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Farmall & IHC Tractors Discussion Forum
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Valve tappet adjustment

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CNKS

03-09-2004 14:44:44




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Adjustment for the H/Super H is 0.017 at TDC with the engine hot. Since getting the exact TDC on the 1/2 rev is difficult since I can't easily see the piston, I have experimented with checking the clearance at points in between the beginning of the compression stroke and true TDC, assuming that both valves are closed through most of the stroke. The tappets seem tighter, perhaps .013-.014 at the beginning of the stroke. Is this normal, or is my cam worn?

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ChadS

03-10-2004 19:55:06




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 Re: Valve tappet adjustment in reply to CNKS, 03-09-2004 14:44:44  
I have been messing around with valve lash adjustments on these farmall engines. From H-706 gas. I use a compression guage to set the lash. Here is what I did on my 54 Super H C-169. I pull this tractor in div 1 in our local club. I warmed it up to operating temp, and removed the plugs, and the valve cover. I used the .017 as the starting point, and the one valve opened, one closed method, adjusted the closed valve tighter than .017. then checked the compression until I got the highest reading, then adjusted the open valve, after repeating the process. The first reading was 129 psi. (firecrater pistons), after this process, peak psi is 155. it first was 38, on the dyno, now it is 44hp. The head is a 8043DD, milled .010, stock head gasket, 3-9/16 firecraters. I had rebuilt this engine about 13 years ago, Dad got it for me for a birthday gift, (Thanks Dad!!) It has been on the pulling track ever since. It is a strong running ol Super H, and my personal favorite tractor in the world!! She runs good! 1st place 2003 points champ, NCIATPA 3250-4500 farm and field class. I can also say that my older sister gave me a good run last year on her 53 Super H as well!! Hers is a bit stronger than my old friend (my super) yet my super always out pulled her, LOL (Sorry sis, I had to!!) LOL Just one of my opinions, ChadS. Steininger Pulling Team, Akron Indiana

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lee

03-10-2004 19:44:07




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 Re: Valve tappet adjustment in reply to CNKS, 03-09-2004 14:44:44  
With plugs removed stick your finger in a hole and bring that one up well on compression stroke. Both valves are closed thru the comp stroke and well into the power stroke so finding exact TDC is not really necessary. Then do the next hole.
A helper can twist the motor for you. That's how I do em. Making the setting can be a little tricky as the valve tips wear into the rockers
so a wide feeler can net you extra clearance.

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Andy Martin

03-10-2004 17:35:42




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 Re: Valve tappet adjustment in reply to CNKS, 03-09-2004 14:44:44  
Interesting. I've never bothered to check a cam in the "closed" position.

I used to always set them at idle but am too old to ignore the flying oil anymore.

The easy way on all engines is like was said, is to set a valve when it's mate is fully open. I never can find chalk so I just go around a couple of times to recheck myself, and I always set them a little loose.

I do have several tractors with rocker arms which have holes worn in them (the reason for this post) by the valve stems. The only way I have found to set them is by the "turn of the screw". Screw the adjuster in until the rocker tightens up, then back off enough turns (about 1/4 turn on an M) until you get enough clearance to not burn a valve.

These worn rockers should be replaced, but if anyone tries to adjust one with a feeler gauge he will be off by the amount of the depression worn into the rocker. I have a '39 M with probably 0.100" depression worn in every rocker but runs smooth as glass when the valves are set right, even with the bad rockers.

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GG

03-09-2004 15:00:44




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 Re: Valve tappet adjustment in reply to CNKS, 03-09-2004 14:44:44  
When I adjust valves, I simply adjust the valve, with its mate "same cylinder", in the open position. I have been doing this for many years and have never had a problem. Just mark the adjusted valve with chalk and turn the engine over untill job is done.



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CNKS

03-09-2004 18:32:09




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 Re: Re: Valve tappet adjustment in reply to GG, 03-09-2004 15:00:44  
I will admit to being somewhat dense, but you lost me. Do you mean you pick an open valve, turn the engine over unil it closes, then adjust? If so that's really no different than what I am doing. Rewording my question -- When the intake and exhaust valves close on the compression stroke, does the required 0.017 measurement increase, decrease, or remain the same throughout the compression stroke?

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GG

03-09-2004 19:33:37




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 Re: Re: Re: Valve tappet adjustment in reply to CNKS, 03-09-2004 18:32:09  
Clearence for the valve is measured when the lifter is off the cam lobe and is rubbing on the round surface opposite the lifting lobe. For example,Let's say we have a one cylinder engine, when the INTAKE valve is open any amount, the EXHAUST valve would be completely closed. Therefore clearence can be adjusted on the exhaust valve. Turn the engine until the exhaust valve is open and the intake valve can then be adjusted. The intake valve does not have to be completely open to adjust the exhaust valve on the same cylinder and Vice-Versa.To sum things up: If you place a dial indicator on the valve tappett and turn the engine over, the indicator will not move until the camshaft lob lifts the lifter, thus opening the valve. Hope this is a good explination.

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CNKS

03-09-2004 20:11:54




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 Re: Re: Re: Re: Valve tappet adjustment in reply to GG, 03-09-2004 19:33:37  
Does the 0.017 measurement increase, decrease, or remain the same throughout the compression stroke? From your answer both intake and exhaust are closed (the way I do it) and the dial indicator (if I had one) does not move as the piston goes up. So I will assume your answer is "stays the same" -- only mine varies about 0.003. I know that regardless of which cycle the engine is in, that a closed valve can be adjusted, but does the piston have to be at absolute TDC when the adjustment is made?? Again, from your answer, apparently not as the dial indicator is not supposed to move until the lobe lifts the lifter. At the beginning of the compression stroke, my feeler guage is tighter than at TDC. So is there maybe something wrong with my valve train? -- tractor runs fine. I am adjusting the valves following a valve job.

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GG

03-10-2004 14:35:59




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 Re: Re: Re: Re: Re: Valve tappet adjustment in reply to CNKS, 03-09-2004 20:11:54  
Many mechanics will adjust valves with the engine running. Most all service manuals state that the number one cylinder must be on top dead center of the fireing stroke to adjust both valves on that cylinder. It goes on to say which other valves can be adjusted without turning the engine from this position. It is then instructed to turn the engine one revolution and adjust the remaining valves. This does not include ALL engines, but certainly includes yours and most other older engines.

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CNKS

03-10-2004 18:00:30




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 Re: Re: Re: Re: Re: Re: Valve tappet adjustment in reply to GG, 03-10-2004 14:35:59  
Thanks for the information. Firing order is 1342. Meaning I can use the crankshaft mark for 1 and 4. 3 is 1/2 rev from 1, and 2 is 1/2 rev from 4. Yes, I could figure which valves are closed with any cylinder on TDC, but having checked a rechecked them all, I believe all are +/- .001 from 0.017. Don't want to adjust with the engine running, because I prefer to work slow, by the time I got done there would be oil all over me and everything else. I have heard of using a valve cover with the top cut out, to prevent getting oil all over.

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riverbend

03-10-2004 07:13:30




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 Re: Re: Re: Re: Re: Valve tappet adjustment in reply to CNKS, 03-09-2004 20:11:54  
It sounds like your cam is ground off center. The base circle of the cam should, in theory be a circle i.e. a constant radius. In a higher speed motor, you could have some valve overlap, and would want to adjust the intake when the exhaust is completely open and vice versa. With these motors, I doubt the quieting ramps are much of an issue either.

As long as the valves remain closed it should be all right. Besides staying shut, the valves all should open the same amount. Interesting stuff. I'm going to check mine next time I adjust the valves .

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