Cam instalation, preperation and break in plus How to flat lap cam buckets/lifter

Preface

All cam and engine work should be done by qualified professionals. We are not responsible for anything regarding the installation process. This guide is meant to serve as pointers to assist anyone in their cam installation. It is not a definitive guide and it doesn't apply to every situation or combination of parts.

It is meant to be used in accordance with the factory service manual. Just because it's not mentioned here doesn't mean it doesn't have to be done. The FSM contains most of the information you need for working on the motor and most things still apply so when it comes to installing the cams, checking oil clearance and everything else related to proper service and assembly of the motor keep the FSM on hand and reference it as much as necessary.

 

Inspecting lifter bores

The general instructions on how to do this is in the factory service manual. On any motor build this is important to check. The bigger your cams get the more important this is. It is also important with bigger cams that this lifter to bore clearance be a little tighter.

On the 16 valve or any shim over bucket it is even more important. A lot of the rumors about only being able to run small cams on shim over is the result of sloppy buckets spitting shims.
Here is the book spec for the 16v head.

16. INSPECT VALVE LIFTERS AND LIFTER BORES
(a) Using a micrometer, measure the lifter diameter.
Lifter diameter: 27.975 - 27.985 mm
(1.1014- 1.1018 in.)
(b) Using a caliper gauge, measure the lifter bore diameter of the cylinder head.
Lifter bore diameter: 28.000- 28.021 mm
(1.1024- 1.1032 in.)
(c) Subtract the lifter diameter measurement from the
lifter bore diameter measurement.
Standard oil clearance: 0.015 - 0.046 mm
(0.0005 - 0.0018 in.)
Maximum oil clearance: 0.10 mm (0.0039 in.)

Maximum oil clearance may be acceptable for the tiny stock cams but is not acceptable for a higher lift performance cam.
Our general rule of thumb for any cam that can be safely run on the stock buckets is this. .015mm - .04mm.
For a smaller cam like say our 262 x 8.7 there is more flexibility on this but you still want them on the tighter side.
On the other hand we have some fairly large cams that can be run on the stock buckets if all preparation is just perfect such as our MG616 turbo cam with 10.56mm lift, and our MG116A 288 cam with 10.4mm lift as well as some of TED components smaller race cams. With cams like these and shim over buckets it is absolutely critical that everything be perfect. In fact we highly recommend you have these heads prepped by TED components to ensure they are to an acceptable spec. If you don't and you have issues then it is most likely due to the head prep .

It is also very important to measure in several places around the lifter and top, middle and bottom of lifter. You are checking for out of round and taper. I will usually measure 3 points at the bottom, 3 points in the middle and 3 points at the top.
You also want to do similar on the lifter bores in the head. They will likely be tapered similar to your lifter with the most wear at the top and bottom and the least in the middle. They will also tend to be more worn in the direction of the lobes path of travel so your caliper would measure smaller holding it axially to the length of the motor but wider measuring axial to the width of the motor or from intake side to exhaust side.

The lifters in the pictures below measure about 27.96mm in the middle which is well within spec. However they measure around 27.7mm at the very bottom and about 27.75mm at the very top which is very out of spec.
If your lifters have any taper make sure that you use the smallest measurement on the lifter and the biggest measurement on the bore for your max clearance spec. Then use the biggest measurement on the lifter and smallest measurement on the bore to check your min clearance.

 

 

Lapping the cam follower

This is a topic that is rarely discussed and many cam manufacturers don't specifically recommend you have fresh contact surfaces on your cam followers. With any cam it would be best to replace or lap your cam followers. If there is any question you can ask your cam manufacturer. TED components recommends you lap your cam lifters on their cams and Matrix Garage recommends you lap your caps for our cams. Both of us consider this mandatory for us to even consider warranty work for failures that could be remotely related to not doing this.

For the 20 valve 4AGE this would be the lifter bucket it's self as it's a shim under design. This is what are used in this tutorial.
For the 16 valve this is the shim it's self as it is a shim over design.

 

If you don't want to buy brand new followers or aren't capable, comfortable or just don't want to do it yourself we can lap your caps for you. Email us for a quote.

Standard lifter lapping is done on an electric lapping machine, however in small quantities, lifters may be hand lapped. Hand lapping is as much an art as it is a science. The outcome will only be as good as your skills and equipment will allow. The most common mistake hand lapping or hand finishing anything is applying inconsistent pressure. In the case of a cam cap this would likely be applying too much force to one edge of the cap wearing that side more than the rest or rocking the cap wearing the edges more than the center. Improper technique could be worse than not lapping at all. Aside from experience the best thing you can do is randomize your method and pay close attention to making sure the cap rests flat against the plate with the most even pressure you can. To do this apply only light pressure so that the abrasive material does it’s job but cutting evenly across the surface of the lifter. Too much pressure destabilizes the lifter creating an uneven surface. Machinist/layout dye can be used prior to lapping to establish how your lifter has worn against your camshaft.  Make sure not to hold the cap in one position for very long. Continue to rotate it in your hand frequently so if you are applying more pressure to one edge you are changing the spot on the cap where that pressure is being applied.

Some people use bluing dye for this. I prefer to read the metal it's self. I do have decades of time spent polishing and finishing surfaces so I have a trained eye. If it's easier for you to use bluing dye or any other tricks then go for it.

The next topic is the surface you will be lapping on. The best surface is a machinists lapping plate that is maintained to proper flatness.

This is a 20 valve 4AGE cam cap. It has been in my prototyping head out in the shop for a while so it has some surface scratches that you wouldn't normally see. You can see the concentric wear marks from the cam spinning the cap.

 

I am using diamond compound, you can also use something like silicone carbide.
I started with 20 micron which is about 1000 grit although the cutting is much quicker than 1000 grit silicone carbide.
My camera also did a surprising job at making the scratches from the compound look much bigger/deeper than they are.
For the first cut you want something that will take out all imperfections in a reasonable amount of time without removing too much material or adding very deep scratches that will take a lot more sanding to remove.

Here is a cam cap after just a few seconds of lapping. This makes it obvious how uneven the cap was. Some wear more in the middle, Some wear more on the outer edge.

 

What we want to do is lap the cap just until the whole surface is flat and you can no longer see any of those imperfections. It should just be a consistent texture. You don't want to lap beyond this though. Keep checking it and stop as soon as it's all gone. Even if there are some light watermarks left they should be lapped out in the next step.
Lap in a small circular motion. You can change diameter of your loops and I prefer to move around the lapping plate a little to prevent lapping a pocket in one spot of the plate. Every 10-15 circles I will spin the cap maybe 30 degrees in my hand or I'll even spin it a little in my hand as I am making my circles on my lapping plate.
I can't overstress the importance of even pressure and not spending too much time in one position or style. I switch from left hand to right about halfway through. This helps mix up the wear pattern on the cap, helps with dexterity and splits the work between two arms.
If you feel the cap rocking or coming off the plate at all stop and figure out what needs to change to prevent it. I use water with a splash of dish soap in it to acquire the desired viscosity. If your lapping compound gets too thick add a little splash of the water and try again.

As soon as the cap is completely flat with a consistent lapped finish wash off your lapping plate with soapy water to remove the coarse grit.
Repeat the process over with something around 10 micron or 2000 grit. Once I think I have polished all the coarse grit scratches out I will do about 5 straight passes pushing straight forward then straight back with light contact making sure not to let it rock. Then I look at the scratches to see if they all go in the same direction. If so I know I have gotten all the deeper scratches out. If so then I will do a final pass rotating and spinning it to get an even finish on it again. If not then I repeat the process until all the deeper scratches are gone.

 

I am going to ceramic coat these with a dry film lubricant coating that I use. If I wasn't then I would repeat the process one more time with 3000-4000 grit or around 5 micron. This should give you a fairly polished surface.

Now your cam caps should be ready to go.
 

 

 

courtesy of webmatter.de