Valve Adjustment Procedure

[Doug_S]

Now I know that this question and topic have been discussed in the past but I didn't get a clear picture of the procedure from the prior posts. I've been working around engines for many years and have just acquired an FJ40. I really like the idea of owning a vehicle that I don't have to pay a "technician" down at a dealership to work on.

With that in mind, adjusting the valves hot with the engine running seems to fly in the face of all that I know about both air and water cooled engines. How do you measure the lash and, if necessary, make adjustments to the screw adjustments while the rockers are rocking? Why not move the crankshaft to the compression stroke and adjust make the adjustment?

I can understand, to some degree, the rationale around it. Hot=all metals expanded to maximum dimension.

?????????


Thanks,

Doug
Olympia, WA

 

[Landpimp]

it can be done and I have done it, but its a PITA, Snap On makes a tool for it). I now do em hot with the motor off, I let the motor run when I am taking stuff off(a 2f even with snog crap intack) will run even with the valve cover off(a 3fe will not) ) so when I get to the adjustment they are still hot.

So just do em when hot not running. I use a remote starter or put the trany in top gear and rock it back and forth.

John H

 

[65swb45]

Good thread here:

https://forum.ih8mud.com/showthread.php?t=12953&highlight=valve+adjustment

 

[IDave]

In my experience, if you do the adjustments cold, the lash values will not be correct when things are running, and you'll end up with problems, missing, etc. Even if you start out warm, by the time you get to the last cylinder, things will have cooled off enough to make the values change.

You can just run them a little loose when you set them cold, but it is tough.

The other thing I have found is that when you stop the engine and set the lash, if you start up again, you will sometimes find the gap has changed a little. It must be a variance of the way the rocker arm sits on the lifter sometimes, a slight torque or something.

So, I measure the lashes with the engine running, using a "go-no go" feeler gauge. If a valve lash is off, I stop the engine and make an adjustment, and then measure it running again. This keeps the temperature fairly constant and at operating temp.

The FSM engine manual definitely says to do it running, and I was convinced (by Charlie "PinHead") to do it this way, and it has worked well for me. Once done, I have rarely had to make adjustments.

 

[Doug_S]

Ok. I seem to be getting the idea. Thanks for the link to the thread. This is one that I hadn't seen and seems to clear up a bit of the confusion for me. The fellow that I bought the rig from says that once set, the valves don't change position at all which is what I've exprienced on other engines that I've worked on.

Now off to find one of those go no-go feeler guages at Napa...



Doug
Olympia, WA

 

[IDave]

Yeah, the valves don't change position. If you go to check them and they aren't right, it is most likely that the temperature was different or the torque thing I mentioned, and they never were right.

 

[ScottFJ40]

Do you have a winch?

I start my engine and run it till warm. I then turn it off. With the trans in 1st, and the tcase in low, I hook my winch rope to a stationary object(6x6 in my case). I then bump the winch to turn over the engine. Just make sure you start out with enough rope pulled from your winch, and make sure you don't run over your foot or anything. Quick and easy and the engine is hot till you are done.

 

[brian]

it's really not that hard or messy to do while running, but it is alot easier with two people. once you do it once or twice you devolope a nack for it.

 

[e rock]

email me direct at fj40eric@verizon.net and I'll send you a pretty comprehensive adjustment write-up written by a local Toy master mechanic. He does it with the motor hot but not running. I did my first using his directions and was nervous at first, but it worked great and was one of the simplest improvements I've ever done.

Eric

 

[dd113]

I have done it running. I can not find the snap on tool that is mentioned. I usually get it hot, connect the remote starter and watch the valves as I bump it over. When they are both closed, more or less TDC, I adj then move on to the next one. It really is not hard to do at all. I adj them then run it and re check them while running the re adj as needed.

 

[sherwood]

So, I measure the lashes with the engine running, using a "go-no go" feeler gauge.

'Wonder which thicknesses you use for the "go" and the "no go" ?
I've used that for years setting up 4-stroke model airplane engines. (The particular engines I run (OS) recommend "cold" and not running. They supply the wrenches and two feelers in a kit.) It always makes me grin, thinking about adjusting the valves in my 1/4 cubic inch 4-banger ;~} http://www.modelairplanenews.com/click_trips/feb04/Valve_1.asp

With the single feeler method, it's slightly objective as to how each interprets the "drag" of the feeler as it passes through the jumping gap....(probably not enough to get anal about)

It might be best, for a first attempt, to set it up using the manual "Hot & Not-running" method and then crank it and experiment as you work UP through the feelers to what feels natural to you. It would be nice to see what someone else uses for "go-no go" measurements.


Thanks,
John Sherwood '79 FJ-40
Charlotte, NC TLCA Upstate Cruisers

 

[sherwood]

Model aircraft engine valve adjustment

Oh........ it should be painfully obvious why you adjust the model airplane engine in the non-running mode............

john

 

[IDave]

You are so right, Sherwood, that the feel with single thickness feeler gauges are subjective (but then, as Soren Kierkegaard once pointed out, "Subjectivity is truth").

I think the go-nogo gauges help a lot. Mine are set up in 2/1000ths inch increments. So for intake I use .008/.010, and for exhaust I use .014/.016.

 

[Doug_S]

Wow,

That was about the most imprecise valve adjustment that I've ever done. I felt like a u-boat mechanic adjusting valves on a 1945 sub cruising on the surface. I can't say that I was that impressed in the "feel" of the go no-go feeler gauge going in and out. While the factory 2F service manual indicates to do the adjustment with engine idling in the tune-up section, there is a more conventional valve adjustment method mentioned later in the book. Why would they provide two methods if both weren't equally acceptable?

The former owner had several of the valves so loose that there were a couple of loud ticks which I was able to quiet some. I know that it's better to hear than smell the valves .

I feel like I've just been sent to check the headlight oil...

Verrrrrrrrrrrrrry skeptical about the benefit of doing it with the engine idling.

 

[s79bj40]

at least it wont snap in half if the valves are slightly out. I think i had mine running on 2 cylinders for a while without probs And the engine has so much weight to it that if you are reasonably fast off the blocks, it wont have cooled enough to be a worry putting the last valves out too much in the adjustments. thank toy for high tolerance engines!

Sam

 

[Doug_S]

That's kind of what I was thinking. I'm fairly quick on the other engines that I've adjusted the valves on. It's not rocket science after all. These things are stone-axe simple - I love it!

 

[65swb45]

In the hundreds of trucks I have tuned up in the shop over the years I have had several that have been very resistant to a good valve adjustment. On these rigs, the go, no-go feeler guage would not provide an accurate reading because the tips of the rocker arms that contact the valves had worn grooves that would throw off the readings.

If you cut down a go, no-go feeler guage til it fits in the groove of the rocker arm for a truck like this, you run the risk of 'floating' the valve should the rocker move to the side at any point.


Soooooooo, if you find the valves are still sloppy after a credible run thru with the feeler guage, you might want to consider pulling the rockers for a look-see.

Mark

www.marksoffroad.net

 

[red66toy]

Ok, so I adjusted my vavles today. Only two exhuast valves needed adjusting. They seemed to tight. Now when I put the guage up to the valves the guage goes in not too easy but not to hard also, is this how it is supposed to be? Also I noticed that something was broken. In the pictures I have circled the part that was broken. One of the little top plates that bolted on top of the shaft was broken in half. The bolt was still there so I suspect the PO knew about it and put the bolt back in. I don't know how long it has been like this(probably awhile). Thanks for the help.

 

[65swb45]

Since you did not circle the entire rocker arm stand, I would assume you were referring to the 'plate' directly above the rocker arm stand. That would be a flat washer!

Feel free to get another at the hardware store.

 

[red66toy]

No, its not the washer. The part that is broken is the top piece of the rocker arm stand. The part that is colored red is the part of the top plate that broke off. Where can I get a new one?