Setting Valve Lash
First off, I’m doing his Write-up because I feel that there just isnt information on these subject matter, all in one place. I do not take credit for much of what I am about to write, I am just condensing all the random information into one place.
The purpose of setting valve lash is to bring your cam lobe to bucket shim clearance into the correct specs per the FSM. Valve lash needs to be checked when either:
A. Valve noise is audible.
B. Installing stock cams or the “91 Hot cam swap”
C. General Maintenance and Rebuilding
In a bucket cam motor such as the KA, valve lash is defined as the space between the bucket shimpad and the cam lobe. In other applications it maybe the space between the valve and the rocker arm, or the rocker arm and the hydrolic lifter.
Setting Valve Lash
Setting valve lash is pretty straight forward. You will need the following tools.
1. Feeler gauges
2. Micrometer or Digital Caliper (Which can be purchased at your local autoparts store or a tool store such as Harbor Freight.)
3. Pen and paper
5. 1 1/8″ or 28mm socket
6. Torque wrench or breaker bar
Step 1. With paper and pen (obviously) write down Intake, and below it write 1-8 in decending order. Do the same for the exhaust side.
Step 2. Remove spark plugs. This makes turning the engine easier.
Step 3. Slowly rotate the engine in the direction of operation, Use the feeler gauge set to measure the tolerance between each lobe and shim, and write the number in Inches or MM in next to the corresponding number.
Step 4. If the clearance is not between .33 -.41 mm (.013-.016” inch), then a new shim is needed to correct this. If the clearance is to large, use a shim that is thicker than the original shim by the amount needed to correct the clearance.
Basically you have 2 options when doing this. You can either A. Remove the cams B. Google Valve Adjusting Tool Kit – Nissan J-38972 and prepair to be raped in the butt.
Most people who are doing this will probably opt for A.
To remove cams, I suggest going here www.jimwolftechnology.com/wolfpdf/CAM%20… as it is aleady complete with instructions and pictures.
When measuring each shim. double check that your caliper or micrometer is set to 0. Be sure to set it to MM before measuring. After measurement, write the correct number beside the corresponding tolerance you measured with the feeler gauges. Do this for all 16 shims.
Here are some examples of the process.
Once once have all your measurements written down, its time to do some math. First you will have to calculate all of your lash numbers to metric if your feelers dont have the metric reading stamped on them. I used this site. mg-jewelry.com/mmtoinches.html
As per the FSM the equasion to find your new shim measurement is: New Shims= Old shim + (lash – .35mm) Add note 2/27/10: To find the new shim for aftermarket cams with different then stock lash, use the new equasion I have listed at the bottom of this post.
So, for example my new #8 intake shim will be 2.21mm + ( .2794mm – .35mm) =N So, my new shim shoud be 2.134mm.
But since shims only come in even numbers, You want to round either up or down according to the last numbers or numbers. >5 round up <4 round down. In this case, a 2.12mm shim was needed.
This equation gives you a tolerance of .0138" so you have a little room to play.
As you can see, I had a 2.11 in the exhaust #8, so I will switch that.
Once you have all your new shims calculated you can easily look to see if you have a shim that will work for what you need.
I was able to achieve this
1 E1 New
2 I6 New
3 I4 Good
4 E6 E5
5 Good New
6 E4 Good
7 I3 Good
8 E8 New
Out of all 16 shims, only 4 new were needed.
Now, install your cams per the FSM's requirments. And enjoy properly clearanced valves.
Note, all aftermarket cams call for a different valve lash to be set then stock. If you are installing aftermarket cams, This spec is listed on the cam card that came with your cams. If you didn't receive a cam card, you can either visit your cam manufacturer's web site, or call them directly to receive a cam card.
Add note 2/27/10: If trying to find the new shim for an aftermarket cam with different lash then stock you can modify the FSM's equasion. To do this convert the new lash (inches) into new lash in metric. Brian Crower lists .008" intake. This is .2032mm. So to find what shim we need for a .008" clearance our new equasion looks as such. New Shims=Old Shim + (lash(mm) - .0232mm) To change the size lash needed, just change the specified lash to metric.
The basic equasion for finding the correct shim is:
Old shim + (old lash - target lash) = new shim
Note this can be done in metric or standard but the new shim must be converted to metric if measurements are taken in inches.
There seems to be a lot of confusion on this subject, and I am by no means an expert, but I know enough to help you get your cams dialed in properly.
Let me start this by saying that I’m still learning, just like alot of you, my information I believe is correct, so I have decided to share my experiences with you. There are a lot of How-To’s on this subject matter all over the net, but I feel that none of it goes into great depths with visuals, on a cam on bucket motor; specifically the KA24DE.
When degreeing-in a camshaft, you’re insuring that valve opening and closing events are in accordance with specifications, regardless of the cause. Actual valve opening and closing events are influenced not only by accuracy with
which a cam was ground, but also timing chain stretch, keyway position in the crankshaft, crank timing sprocket, and dowel pin hole position in the cam sprocket also play a major role.
The most accurate way to set camshaft position is to properly degree the cams. This way you can be sure the cams are in the right position regardless of engine variations, deck heights, and cam gear marks. Cam degreeing can also be used to check valve opening and closing positions, durations at various lifts, and peak lift measurements.
Note using the centerline method to determine valve events is NOT an accurate way to degree your cams. Your engine does not care where the centerline of your cams are. What will determine your power band is your actual valve opening and closing points.
The intake valve’s opening point and your exhaust valve’s closing point are the most important specs to follow. These two openings determine two things, lobe overlap and lobe sepatation angle.
The link below is to a glossary so you can know what all this jargon means.
To degree your cams you will need a few items and tools.
1. A degree wheel. (There are many of these that you can print off for free on the internet. I bought mine from SummitRacing. Note, if you are doing it with the engine in the car, or with the water pump on, you will need a 7inch wheel. Most degree wheels will not clear the waterpump. This is where I got mine store.summitracing.com/partdetail.asp?au…)
2. A dial gauge and a sturdy base. A magnetic base will not work on our heads, because well they are aluminum. I got my dial gauge again from SummitRacing.
3. A solid pointer. Coat hanger, welding wire, or something else like this will work fine.
4. A breaker bar or Torque wrench.
5. A 1 1/8″ or 27mm socket to turn the crank bolt.
6. A Thick medium length Flat head screw driver
7. 4-6 inch long, THIN dial gauge extension. Pointed is preferred.
8. Pen and Paper
9. a set of Adjustable cam gears (Found here www.jimwolftechnology.com/customer_part_…
10. 24mm or 15/16 socket
11. 1inch adjustable wrench
First we need to loosen the crank bolt. The way I do this, is to wedge a screwdriver behind the radiator support and a slot in the crank pully. Using a breaker bar, loosen, but do not remove the crank bolt.
[b]Start off by finding true TDC. To do this, turn your crank till you have it at the approximate tdc mark on the pully. This mark is the 2nd one on the left.
Remove the crank pully and install the degree wheel. You will need to use the washer for the crank bolt and the correct bushing to be able to clear the stock timing needle. Place a large brass washer on the front of the wheel so you can turn it later on. Take care when tightening the crank bolt that you dont turn the crank past tdc too much, and not too loose that the degree wheel flops around.
Now turn the wheel to match the TDC on it to the stock needle.
Now install your pointer. You can mount it on pretty much any bolt you want. I find there is a nice spot on the right side of the water pump. Bend it and point it in line with with the stock timing needle. Bend it in the angle of the TDC mark so you can easily read your findings.
The method we are going to use here to find TDC is with a dial gauge. You can also use the piston stop method, but with older engines or engines with looser then normal tolerances, meant for racing, this can impose some mathematical errors.
You can use the piston stop method, but I chose not to.The method will not be discussed here, but is easily found by Googling “degreeing cams”.
Now unscrew the base off of your dial gauge. There are 2 holes in the very front of the head, between the cam gears that is the perfect thread to mount in. Screw in the shaft and tighten it slightly with a pair of pliers or vice grips.
Install your extension into the shaft of your dial gauge. Line up the dial gauge in the center of the spark plug hole, and drop the gauge down, preloading it just a little bit. After this is done, set the face of the dial gauge to 0.
Now slowly turn the crank in the direction of rotation, you will notice the needle on gauge will spike then fall back down. Do NOT turn the engine backwards from this point forward. Complete one full cycle of the engine, back to approximate tdc. Keep turning the engine until the point where you see the #1 piston dwell at the top of its stroke. Set the gauge to 0 again. Complete 1 more full cycle this time stoping at .010″ before TDC.
Go to your degree wheel and document that number. Now slowly turn the engine again till the piston peaks and starts to fall. Once you reach the same .010″ after TDC, stop again. Document this number.
Example: The first number you wrote down was 4 before tdc. and the next was 8 degrees after tdc. Add these 2 numbers together and devide by 2. 4+ 8= 12 /2 = 6. TDC is half way between the 2 numbers. Turn the crank to this number. Set your degree wheel to TDC. This will be true TDC. Set your dial gauge to 0 and make another full revolution, ensuring that 0 is read on the dial gauge when TDC is reached on the degree wheel. Repeat the steps above until true TDC is reached. You will not turn the degree wheel after this point.
Degreeing the cams
This is probably the hardest part. You need to set your dial gauge to the one of the lobes on the intake cam for the #1 cylinder. It is very important to make sure to keep the dial gauge parrallel with the angle of the valve! Geometrical errors will be incurred if this is not maintained. Note is takes a little work to get the angle you need, while keeping the point of the gauge on the shim pad.
At this point you want to make sure your extension is as thin as possible, with a pointed end.
I found it was helpful to slide a feeler gauge between the 2nd cam lobe and shim to extend the veiwable angle of the bucket.
Make sure the engine is at TDC and there is no load on the shim pad. You can verify this with a feeler gauge. Preload the dial gauge to about 1.5″ then carefully set the dial gauge to 0.
Now, slowly turn the crank 1 full revolution past BDC and back to TDC and verify that your dial gauge goes back to 0. If it doesn’t keep messing with it till you achieve a good contact and motion. Also be sure the tip of the extension stays on the shim!
Once you are sure that the dial goes back to 0 everytime, its time to check our timing events.
Slowly turn the engine the engine forward so the intake valves start to open.When the needle on the gauge gets close to .050″ slow down, and stop on .050″. Go to your degree wheel and document this number. The first number your write should be labeled After TDC or ATDC
Now slowly turn the engine forward again, past the cam’s peak lift, toward intake valve closing point. We are looking for .050″ right before the valve closes completely. Once you have this, and it may take you a few times to get the timing right, document this number. This number should be labeled ABDC
Just write down the number you see, dont try to over complicate things by trying to add stuff to the numbers.
Now just do the same with your exhaust cam.
Once you have your numbers, you should have something like this written down
Note your numbers will probably vary from mine, which is ok. Lots of factors come into play here as discussed at the beginning of this How-To.
Intake Open ATDC: 18.5
Intake Close ABDC: 49
Exhaust Open BBDC: 44
Exhaust Close BTDC: 14
Now plug your numbers into this cam calculator www.wallaceracing.com/camcalc.php
You will need to place a – in front of the opening values of the intake if the reading is ATDC and also before the exhaust closing readings if its BTDC.
It will tell you everything you need to know about the profile of your cams. From here you can start playing with your cam gears.
Example: My cams have an Overlap of -32.50 degrees and has in Intake Duration of 210.50 degrees @ .050″ lift.
The Exhaust Duration is 210.00 degrees @ .050″ lift.
The Inlet Cam has an Installed Centerline of 123.75 degrees ATDC.
The exhaust cam has an Installed Centerline of 119.00 degrees BTDC
Again, as stated above, your engine does not care where your cams centerline is. It is not accurate to use the centerline to determine cam timing. The real way to degree your cams is to set your intake valve opening and your exhaust valve closing points. BC calls for the intake to open @ -12 atdc and the exhaust to close at -9btdc.
As you can see, with my lash set to stock, I am a little off off. Adjusting lash on BC v2’s nets around 1 degree per .001 of lash. It can be different for all cams, because this number depends on the cam profile.
My first lobe is @ .014 and BC calls for .008. Thats .006″ of lash to be tightened, which translates into roughly 6 degrees.
If you look in the posts below, the CORRECT BC cam card is now listed below and the How To was updated accordingly. You can see the post that solved this problem here —> www.ka-t.org/forums/viewtopic.php?t=4853…
So we can say -18.5-6= -12.5 degrees which is perfectly within the margin of error and my cams will be pretty much spot on to spec. From there I can degree them to where I’d like the powerband to be.
Now when I tighten my exaust lash from .014 to .010 that should give me around 4 degrees of duration back on my cam. This should also move my timing from -14btdc to -10 btdc.. which is only 1 degree off from the cam card and is perfectly acceptable, which is GREAT news for all the guys wanting BC cams.
To find your cams overlap you simply add the intake opening + exhaust closing point.
Using the BC cam card we can say the intake opens @ -12 atdc and the exhaust closes @ -9bdtc. So -12+-9= -21 degrees of overlap.
Determining Lobe Sepatation Angle
This is basically the distance in degrees, as measured on the cam, between the point of peak lift on the intake lobe and the peak lift on the exhaust lobe.
The LSA is calculated by adding the intake centerline and the exhaust centerline, then dividing by two. For example, a cam with a 106-degree intake centerline and a 114-degree exhaust centerline has a lobe separation angle of 110 degrees (106 + 114 = 220; 220 2 = 110)
The BC V2’s have an LSA of 119.5 which is fairly wide compaired to high overlap N/A cams, which means that power is going to hang on a lot longer but give up a little torque.
If you still have some confusion, check out this video and it will help some also: www.youtube.com/watch?v=ntHPLXE5juE
If anybody needs any help getting their setup dialed in please PM me with the type of cams you are running, your current valve lash, how much boost you are running, and the size turbo you are running. Also let me know where you want your power band to fall.
Enjoy! I hope this helps clear up some of the confusion dealing with degreeing cams on the KA-DE.
If I missed anything or if you would like me to add something, let me know so I can update this asap!
Thank you to everyone in the community that has had a hand in providing information for everyone’s learning experience.