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CJ3B Bulletin Board > CJ-3B Posts > valve adjustment

Title: valve adjustment
Description: TDC and exhaust valve woes

yjcanibul - September 6, 2011 07:08 PM (GMT)
i find the mech manual and web pages a bit lacking for me, i have done at
least 2 valve adjustments in my day but both were ohc and manuals had
good instructions for those dangerous with a wrench ... some pages I found
elsewhere assume u can see through the block so need help :

two questions :

#1) i turned crank to TDC, i can see in spark plug hole the exhaust valve is closed,
both intake and exhaust in this position are a little loose so i know i am TDC, whats
the best way to continue on to next piston - everything I read seems kinda vague in knowing exactly when both valves are closed - even looking in sparkplug hole i cant be 100% sure exhaust is seated - anyone got a simple way like turn crank 90deg todo piston #n or something to go on

#2) EXHAUST Valves - "adjusting", mine doesnt look like pictures in mechanics manual, the mechanics manual looks to be 1 nut you probably turn clockwise to widen gap and counter clockwise to narrow gap and no locknut visible

mine from bottom up has a lifter and a 1/2" nut on top, least thats all I can see peeking in , so the 1/2" nut is a lock nut ? - so I would turn the lock nut counter clockwise holding the lifter to free it from lifter ? , if so what am I turning to lesson or wide the gap ... maybe I cant see something else above the lock nut (below rotocap) but currently at a lose how to continue - valves are out of adjustment on #1 no drag at .016 and i assume same down the line ...

thanks in advance

yjcanibul - September 6, 2011 09:28 PM (GMT)
to find TDC would following be 98% accurate

- using old rotor / cap drill out wire holes, paint rotor tip white
- for #1 rotate crank 0d mark on timing cover compression stroke, rotor should have been visible at the 5d mark just prior
- for rest follow firing order, rotate crank till see rotor (5d BTDC) then 5 degree past ( 1/2 inch more rotation )
- now at 0d TDC adj int/ex for that cyl

thoughts ?

jeeper50 - September 6, 2011 10:29 PM (GMT)
I found it much easier to adjust the exhaust valves with the left fender removed for getting into your work.

Oldtime has a good recipe for how to adjust valves...

yjcanibul - September 7, 2011 01:44 AM (GMT)
just finished reading oldtimes post, thanks jeeper

when i did my 258 valves ( rocker arms, torque each set when TDC ) i made myself an index out of a pringle chip can lid, i carefully scribed the plug #s on it and indexed it to cap position, as i rotated crank watching timing mark on pulley
and/or rotor i could see which piston was hitting firing position and turned crank "timing degree's past" for TDC ... engine sounded sweet when done - this seems to correspond to late 60's instructions from Kaiser

i understand what oldtimes saying except how do I know the opposing valve
is fully open as i can't see it - i cant watch the valve springs compress/release like a ohc engine least not the exhausts - what am i missing ?

user posted image

yjcanibul - September 7, 2011 03:08 AM (GMT)
got my exhaust manifold off now but still not limber enough
to see whats just below rotocap but my camera fit

so all i got is a lifter and a nut, when i turn the nut the lifter turns,
i see the lifter is machined on 2 sides so i can hold it with 1/2" wrench

so is that it, hold the lifter and turn the nut up/down to adjust gap

user posted image

yjcanibul - September 7, 2011 04:55 AM (GMT)
found pic below on 3A page - 10 to 20 ft/lbs to turn holding the lifter ( tappet ) using 2 thin 1/2" wrenches - so adjustment question #2 solved

so, back to question #1 finding the optimal position to adj int/ex valves, TDC
i can find using my pringles chip lid though maybe not 100% accurate i think its pretty close , but i am not clear how the various other examples of turning the crank you can determine if valves are open or closed or somewhere in between ... what are you looking at ? my first thought is if the valves are out of adjustment then fully opened or closed might not be positioned correctly ...

from 3A page, turning screw clockwise increases gap , 10 to 20 ft/lbs of
pressure required to turn , no lock nut
user posted image

spm1us - September 7, 2011 11:12 AM (GMT)
Regardless of engine type, mfr, gas, diesel, etc - the simplest and easiest way to "run", i.e. "set" the valves is:

1) Set Intake clearance when Exhaust valve opens.
2) Set Exhaust clearance when Intake valve closes.
3) If you do not have a good feel for the amount of drag on the feeler gauge, then use the "Go/No-Go" method whereby you use two gauges at .001 over and .001 under the desired clearance - ex> for .018 clearance, then use a .017 & .019 feeler gauge and you'll get the hang of it.

With this method you can run the entire bank by simply rotating the engine and setting the valves from front to back. Guaranteed not to fail or miss a valve with the other methods. Pull all the spark plugs to make it easier on the starter.

Hope this helps, Sam Michael Jr, Jax, FL

jeeper50 - September 7, 2011 12:33 PM (GMT)
I used two thin 9/16 wrenches and slightly bent one to provide knuckle clearance for my hands. be advised if your tappet adjusters are cupped from wear all you can do is get close to the spec dimension.
The 503 has a good pick of that problem I'll see if I can post a link for ya.

Link to pic showing valve adjuster wrenches halfway down the article
Link to info about adjuster wear;

yjcanibul - September 7, 2011 06:50 PM (GMT)
great tips thanks, since my eng is old think i might set
exhaust to .017 to compensate for some guesstimated cupping;

obviously lack of experience is hindering me getting the valve
in optimal position to adjust, in the tips like oldtimes its
well laid out what the target valve is but i got no feel for
accuracy while turning the crank - if both int/ex were up top i
might have had a chance.

will give the eng a couple of spins tonight to see if i can catch on ...

otherwise i am going to make a 4cyl pringles chip lid device for under rotor
to find firing position (5deg BTDC) on compression stroke in firing order then
advance crank 5deg (width of 5 to 0 timing mark) should put me
at TDC - both valves closed, that I can see and understand as it
looks correct on #1 in terms of indexing
crank pulley (0deg mark) / cam (valves loose) / distrib rotor leaving #1;

just a thought - why dont they make clear distributor caps these days ? ,
that be cool light show at night ...

Dougie - September 7, 2011 10:52 PM (GMT)
I think you're possibly making this more difficult than it really is. It's not like the cam lobe needs to be EXACTLY opposite the follower when you're adjusting it, after all, the valve is supposed to be closed most of the time.

The only thing I really worry about is to be sure to make the exhaust valves have "generous" clearance. That reduces the possibility of burning a valve, makes the engine perhaps slightly noisier, and may reduce the performance some imperceptible amount. Having gone through burnt valve problems in the past (on other vehicles), I may tend to be a bit over-cautious on this point...

oldtime - September 7, 2011 11:42 PM (GMT)
If the adjusted tappet is not directly resting upon the camshaft heel it can and will effect the accuracy of the adjustment.

Adjust all valves with the engine cold.
Intake = .018"
Exhaust = .016"

I suggest you use a flat feeler gauge and the gauge should be a snug fit with the cam lobe setting on its heel. (lowest point)
Realize that you cannot see the camshaft to determine its exact position.
So how do you know if the tappet is on the exact center of the lobe heel ?
I use a technique that I call "the opposing valve technique".
The techique can determine when any particular valve is fully closed and the tappet on dead center of the camshaft heel.
The #1 and #4 cylinders are exact opposites, also the #2 and #3 cylinders are exact opposites.
You cannot see exactly when a valve is fully closed but you can definately see when any valve is fully open.
You can look at the #1 exhust to deternine the position of the #4 exhaust and so on and so forth.
If 1# exhaust valve is fully open then you deduce that the #4 exhaust must be fully closed.

yjcanibul - September 8, 2011 02:21 AM (GMT)
QUOTE (oldtime @ Sep 7 2011, 04:42 PM)
You cannot see exactly when a valve is fully closed but you can definately see when any valve is fully open.

might be getting it - i can see the valve is fully open because ... its valve spring is fully compressed ?

oldtime - September 8, 2011 11:34 PM (GMT)
Rather than explain how the camshaft eliptics work in relation to the tappets ....
I'll just detail the exact procedure.


Adjust all tappets with the engine cold.
Set Intake tappets at .018".
Set Exhaust tappets at .016".

Use flat bladed feeler gauge and adjust for a snug feeler blade fit. (not loose and not overly tight)

Firing order = 1342 / Tappet adjusting order = 1342

From the front of the engine rotate the crankshaft clockwise till you see:

1) When the # 4 exhaust tappet is fully up. Now adjust the #1 exhaust tappet.
2) When the # 2 exhaust tappet is fully up. Now adjust the #3 exhaust tappet.
3) When the # 1 exhaust tappet is fully up. Now adjust the #4 exhaust tappet.
4) When the # 3 exhaust tappet is fully up. Now adjust the #2 exhaust tappet.

5) When the # 4 intake tappet is fully up. Now adjust the #1 intake tappet.
6) When the # 2 intake tappet is fully up. Now adjust the #3 intake tappet.
7) When the # 1 intake tappet is fully up. Now adjust the #4 intake tappet.
8) When the # 3 intake tappet is fully up. Now adjust the #2 intake tappet.

You can see when any tappet is fully up because it will soon go back down.
If you rotate the crankshaft too far simply turn it back to find the tappets highest position.

yjcanibul - September 9, 2011 01:24 PM (GMT)
got it ! , can do them this weekend with confidence

thanks oldtime and everyone who replied

yjcanibul - September 10, 2011 09:36 PM (GMT)
went smooth, cycled thru them in no time at all,
had tightened head bolts first and found most valves
didnt have enough gap

used mirror so i could spin crank and watch, found
this thin wrench in with bike stuff to hold tappet

user posted image

i also had luxury of manifold removed ( read my horror
here )

with the great instructions it was just like oldtime and
everyone was with me spinning wrenches

thanks !

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