1948 Model B tractor
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=139953
Printed Date: 23 Sep 2025 at 6:52pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 1948 Model B tractor
Posted By: stevebei
Subject: 1948 Model B tractor
Date Posted: 30 Jun 2017 at 11:02am
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Hello, I just received my cylinder head back from the machine shop after a valve job. What is the best way to set the valve lash from scratch? In doing the valve job the machine shop replaced the guides and installed valve stem seals. Since originally valve stem seals were not used should I be concerned? ------------- 1948 Model B |
Replies:
Posted By: Gerald J.
Date Posted: 30 Jun 2017 at 12:01pm
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Valve stem seals should keep oil from leaking around the stems, hope there is enough to lubricate the valves though. I have a shop manual that covers B, C, G, and CA on line at: http://www.geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf" rel="nofollow - http://www.geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf There probably is more on valve setting in the operator's manual like the B military manual: http://www.geraldj.networkiowa.com/Trees/BMilitary.pdf" rel="nofollow - http://www.geraldj.networkiowa.com/Trees/BMilitary.pdf Gerald J. |
Posted By: Dick L
Date Posted: 30 Jun 2017 at 4:04pm
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Here is the way I set the valve lash. I do one cylinder at a time. I bring each piston to top dead center for the compression stroke. This is where both valves are closed and the rocker arms are at there highest. The book calls for .010 and I set them with a .012 feeler gage. I like them looser than the .010. I want to be able to push the feeler gage in and pull it back several times with only a slight drag. After I have each set of valves set to the .012 gap I go back thru them again to recheck. After the engine is running and warmed up I re torque the head and re set the valves. As a side note I was taught in the 1950's to do the final valve lash setting with the engine running at slow idle. I have not set them that way in years. I was also taught to re check my work more than once which I fail at quite often now and pay the price.  
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Posted By: Bill Long
Date Posted: 30 Jun 2017 at 8:48pm
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Listen closely to what Dick L Says. He is one of the finest mechanics I have never met. Frankly what he says is the way we used to do it when we set up the valves. Be sure to run it a while then re-adjust all the valves. You will be suprised at the amount of difference. Also, we did it with a non running tractor. Some could but not me. You may want to run it a little with the valve cover off. That will let you see if the valves are getting oil. I not we used to put awire in the last valve to "coax" the oil. In any event take good care of my favorite. Good Luck! Bill Long
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Posted By: Dick L
Date Posted: 01 Jul 2017 at 8:05am
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Setting valve lash at idle is setting by ear. As soon as you tighter than the feeler gage the valve does not seal and you can here the hiss. You don't have to worry if the drag of pulling the feeler gage thru is loose enough or to loose. At times when double checking the gap without the engine running I have found I was tighter than I wanted to be. When setting at idle doing a double check as soon as the feeler gage is between the valve stem and the rocker pad it will miss/hiss if it is to tight. No guessing. Just for those that was thinking what was that setting valve lash at idle about. |