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Valve lash/pre load
Okay, so I decided to replace my valve cover gasket because it was leaking. I decided while it was off I would adjust the valve lash per instructions in the Chilton manual. That didn’t get all the chatter out so I decided to try the method of adjusting while the engine is running. I could get it dialed in then it would start to chatter again about 15 minutes later. I thought the adjusting nuts may be done so it went by my local engine rebuild shop to grab some new ones. The guys there said that the 300 inline six is non adjustable so I just need to seat the bolts all the way down. So my question is do I just tighten it all the way down or am I going down a different rabbit hole? Also in all of this I have noticed that one of my lifters is not getting oil. Should I replace that while I have everything apart? |
If you have bolts, they are not adjustable. Just tighten them down, I want to say it's 25 ftlbs or something like that. Most Ford valve trains in the later years were not adjustable.
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On the lifters ticking and the one having no oil, you can try a can of Rislone. Run it in the oil for a month or two and it will usually open the clogged holes up in the lifters.
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Thanks Franklin2 for the quick reply! Okay. I’ll crank those bolts down. The Chilton must be covering older vehicles. It runs a little rougher when I do that but the lifters will adjust I assume because of their hydraulic nature? |
So I pulled out the ole torque wrench. Tightened everything up and it runs worse now. Stumbles and vibrates more like it's being choked. I will say they weren’t torqued down to begin with, which maybe why they were ticking. Maybe the Rislone will help that too? |
So I’ve been doing more reading and I want to make sure I understand everything. I put the piston I’m setting the rocker arm preload at TDC of the compression stroke. Torque the bolt to 25ft.lbs. If it takes more than one turn to accomplish that I need a shorter push rod. If I need shorter push rods is that because the cam is worn down? I ask because I wonder if this is a sign of problems to be addressed further down the road? Like the needing to replace the cam. |
You are correct, you can set each piston to TDC and check the pre-load, even though you can't set it. There is a way to fudge it if they are more than a turn like in your case, sometimes you can make shims and put them under the pedestals.
Do your rockers look like the picture below? http://image.carcraft.com/f/9245731+...ocker_arms.jpg If those look like your rocker system, you can buy shims to fit under the pedestals. Here's one place you can get them. https://www.jegs.com/i/Crane-Cams/27...IaAhqTEALw_wcB If your cylinder head has ever been re-worked and they didn't do it right, then you can be in the situation you are in. Another reason would be high miles and lots of valve recession. A aftermarket camshaft can also cause this. To put the shims in place, you will have to do what you have been doing, turn the engine to TDC on each cylinder, and check the clearance by turning the bolt and then adding shims to make the bolt turn about 1/2 a turn when it gets tight. If you are have to go the other way (not enough turns on the bolt) then you do have to change the pushrod. Not sure if you can grind much off the bottom of the pedestal without getting into trouble. Of course you can't shim too much either, the pedestal still needs to nest inside the groove when it is tight to keep it from turning. |
Franklin2, thanks. No engine rebuild untouched engine. So it’s 36 years old so it’s probably a bit worn. I was reading about shims. You would go with that over different pushrods? My rockers are different I’ll attach a photo below. https://cimg7.ibsrv.net/gimg/www.for...eb6e37598.jpeg |
You have studs and nuts. I am going out on a limb here, you need to do some more research, but they do make adjuster kits for v8's with those type of rockers. It looks like you have the rail rocker system. They used those on the older v8's, and the kits were a extra long nut, with a set screw in the end to lock them.
Here's a link to some on ebay. Looks like you can buy them in pairs. Keep searching, you can get them other places. You can see these are for 7/16-20 threads. Make sure your studs are those threads, they may make them in different sizes. You can see in the picture they are a very tall nut with a hex on the top for your wrench, and in the middle is a allen screw. When you get the lash correct, you hold the tall nut while turning the allen screw, the allen screw jambs on top of the stud and locks the whole thing from turning. https://www.ebay.com/p/Crane-Rocker-Arm-Adjusting-Nut-7-16-20-in-Thread-2-PC-P-n-99792-2/1417815744?iid=332073507815&chn=ps |
Franklin2, I’ll look around. I have an in-line 6. 300/4.9 to be specific. I was thinking of throwing a washer on top of the rocker arm and see if that gets me to the proper preload and torque. Bad idea? |
Washer on top will do nothing except move the nut higher. You need to let the rocker arm ride higher. You can't just leave them loose like someone else did, they will work their way even looser and you will keep having problems with it. If you do a little verification of the thread size, something like I linked to should work. Try down in the six forum down there and see if one of those guys knows any more about what you could use.
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Right on Franklin2! Thanks for all the help! |
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