How To Set Valve Lash

The Butcher scrubbed and stretched on the sterile rubber surgical gloves. He was about to perform a new operation. The parts that ride along the camshaft are the lifters. Here are some simple and educational animated examples of a cam and a lifter in action. In this first picture, the cam is black and red...the lobes of the cam would be the red parts. The purple jobbies would be the lifters and the light blue would be valves.
Animation Of A Camshaft

Now here is a more complex example where the rocker arm is introduced. the blue thing is the rocker....hey! and in my picture above the rockers are blue too! :) The lifter would be that red part, and valve is the silver part on the other end of the rocker.
Animation Of A Rocker Camshaft At the top of this next page is the very cool SOHC or single overhead cam, and at the bottom is the more common pushrod setup

4 STYLES OF LIFTERS
Lifters generally come in 4 flavors:

Mechanical or Solid Flat Tappet
Mechanical or Solid Roller
Hydraulic Flat - Tappet
Hydraulic Roller

In the olden days, everything was Solid Flat Tappet. You basically had a flat tube of metal with a slightly rounded face, and this rode over the cam lobes. These lifters are still used today and usually cost less than hydraulic cams. Mechanical flat tappet cams are also required in many pure race engines where engine speeds can reach 8500rpm. Most hydraulic lifters are only safe to use up until approximately 6500rpm.

I just checked the Crane website and it states that the main difference between mechanical and hydraulic lifters is that the hydraulic lifter pushrod seat is moveable, the mechanical lifter seat is not. There is a good explanation with pictures of it here. Crane states that these are the reasons why hydraulic lifter cams are becoming so popular:

1. Quieter
2. Less maintenance
3. An ability to adjust for thermal expansion of the engine
4. Built in shock absorber, eases stress on valve train
5. Bleed Rate can be designed to accommodate different engine RPM ranges

Hydraulic Roller...these have the hydraulic benefit of the flat tappet and then have the added benefit of being a roller, rather than a flat piece of metal. They are sort of like a ball point pen. Here is a great picture of the difference between flat lifter and a roller lifter. Two of the main benefits of rollers are 1. More radical hydraulic roller cam profiles deliver increased torque and horsepower plus higher RPM operation! 2. Increased rate-of-lift delivers much broader power band for peak torque, horsepower, and improved idle!

Solid Rollers are the style of lifters I have in the butcher 383 TNT. Crane makes at least 8 types of solid roller lifters. The reason choose this style of lifter was
1. Again with rollers you can choose more radical cam profiles
2. I wanted to an engine that would rev to 7,000rpm with no troubles. A hydraulic roller would be risky when pushed to that range.

The drawback of a solid roller setup is they make more noise than hydraulic. The noise might be considered a little like timing gear whine. I can hear it but it does not bug me and in a cobra the pipes are already so loud that you can hardly heard anything. They need to be adjusted every once in a while...maybe every 5000 miles to insure the valve lash distance is correct. This is the reason for writing today's cobra lads story. I've got a few more good links before we get to the good stuff :) Here are some nice pics of solid rollers. Here is an explanation of what some of the styles are best suited for.

Therefore, if you use a hydraulic solid, or hydraulic roller, you generally set it once and then can almost forget about it. If you use a Solid Flat Tappets, or Solid Roller lifters, then you must regularly adjust valve lash to insure it is within factory specs. Here is the professional explanation of what I am getting at today.

It's time to set the lash, or the distance between the rocker and the valve. In one of the animated examples above, that would be the space between the blue arm and the silver valve tip. Here is a nice blow up example on the comp site. See in Diagram A where the thing that has 3 red arrows on it is touching the rolling end of the rocker arm...this is the gap we want to set on a mechanical lifter engine.

Every cam company is different. Some tell you the distance they want when the engine is COLD, and some give a dimension for when the engine is HOT, and some give both. My cam spec card in section two states that it should have 0.020 on the intake and 0.020 on the exhaust while the engine is HOT so I can do a great job at burning my fingers.

You need three tools: a wrench, an allen key, and a feeler gauge for 20/1000th of an inch. I started by loosening the nut with the wrench. I forgot to mention a critical step. You first need to have the valves you are working on at their highest point. Originally I was going to rotate the engine and watch the valves in order, they working on one at a time as it was near its top dead point. I moved the engine a bit and decided it was simpler just to watch the valves as I bumped the engine and then stop and work on the ones that were at the top. You can wiggle them and see they are not moving. Generally you can find 2-3 at any given time that can be worked on. Gary told me that when they used to do it, they had it down to a science where you could work on valve XYZ when the engine was turned 90 degrees from TDC and then 45 more degrees you could do ABC. They used minimal rotation and were able to do all the valves in a very efficient manner. I just would bump the engine randomly and hunt for the ones that were in proper position. By the way, here is a handy painless wiring product that has some in handy, countless times. This is an "in engine" starter button with relay. If you need to start the engine while working under the hood, or if you just want to do what I did an bump it over a little, this really saves time. Here is the painless picture of it and it is part #30201 and it can be found at places like martel bros or racesearch.

First I would loosen the whole lock nut system with a wrench. I then would back off the middle locking set screw a turn or two. In went the 020 feeler gauge. I found that by moderately finger tightening the big distance nut, that that would put me very close to 020. I would check with the gauge one more time, hold the wrench steady, and tighten the center to lock it.

This is why I call myself the "Butcher" This was honestly, the very first valve I worked on. I snapped that cheap ass tool right in half! Aye Carrumba. Into the trash all those Cheap T handles went and back to the classic L shaped allen keys...the ones that melted to my sidepipes a few weeks back :) I don't have an actual pic of the whole operation since it takes three hands...but once the space is correct, you tighten the center with the hex key.

The whole operation might of taken 30 minutes and if I did it again, I think it would only take 15-20minutes. It was a lot of fun an much less tricky than I expected. I was worried that the engine was getting cool as I went but it was still pretty darn hot to the fingers. I just found this page in the ARP catalog that shows what I was up to.

Richard JBL then suggested that I could also take a cold lash reading at this point. The next day, mainly out of curiosity, I went back and checked. The distances had all shrunk and I estimate that they were somewhere between 0.012 and 0.015. I only had those two feelers...if I had to guess, I would think 0.014 was where they sat cold. Now I just read the Crane Cam huge and excellent tutorial on this and check this out...they say that "With iron block and aluminum heads, subtract .006” ...How about that! 0.020 - 0.006 = 0.014 ! and that is exactly what I discovered. Please note that Crane warns that there are some special TIGHT LASH cams with very low HOT lash settings of 010”, .012”, or .014” and these MUST be set hot.

I just wanted to make one additional note to the above adjustment guidelines. It's been suggested that my method of randomly bumping the engine around and hunting for loose rockers is perhaps not the safest method =) Here is the method from Crane on positioning the rockers at the proper point for adjustment.
1. When the engine is hot (at operating temperature) remove the valve covers and pick the cylinder you are going to adjust.

2. Hand turn the engine in its normal direction of rotation while watching the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder’s intake valve. (Why? Because when the exhaust is just beginning to open, the intake lifter will be on the base circle of the lobe, so the intake is the one we can now adjust.)

3. Use a feeler gauge, set to the correct valve lash, and place it between the tip of the valve stem and rocker arm. Adjust until you arrive at the proper setting and lock the adjuster in place.

4. After the intake valve has been adjusted, continue to rotate the engine, watching that same intake valve. The intake valve will go to full lift and then begin to close. When the intake is almost closed, stop and adjust the exhaust valve on that particular cylinder. (Again, when we see the intake valve almost closed, we are sure that the exhaust lifter is on the base circle of the lobe.) Use the feeler gauge and follow the procedure described before in step 3.

5. Both valves on this cylinder are now adjusted, so move to your next cylinder and follow the same procedure again. In the future you may find shortcuts to this method, but it still remains the best way to do the job correctly.

While working on the valves, I had to remove the valve covers. Here are two parts that I highly recommend...a gasket and a stud kit (with flange nuts)

1. Moroso Perm-Align Valve Cover Gaskets
Now these gaskets are not cheap, but they are awesome. They are thick as can be and have a metallic center. They hold their shape and can be really clamped. I love them and would never go back to cork. Jeg's carries them. Here is a picture of it on the head.

2. ARP stud kit for valve covers
Dean at HOC tipped me off to this and I wonder how I ever did it the other way with bolts. I highly recommend the valve stud kit. It makes gasket and cover placement a breeze, and I have had no oil leak troubles since going with studs and the blue gasket. Here is the page I bought from at Jegs.

One things I changed was the nut. First I tried nylocks, which I suspected would not work. I blue loctited the studs, but the head heat is so high that it breaks the loctite bond so nylocks just pull out the stud. I decided to go with a flange nut. These are Butcher extra beefy style nuts with a huge flange, like a built in washer. One thing I don't like on the valve cover studs, are washers. They would become a pain in the butt at the track or when taking the cover on and off. The flange nut makes a nice compromise. Of course I buy these at mcmaster where they can be found in the flange nut section (but you need to go to main page to order). Wait just a second! Do you see what I see? I almost wet my panties....the top of the food chain, industrial, grade 8 flange nut...Ar Ar Ar. I need some of those for the chassis.

"The Samurai" and "The Butcher " have booked appointments on the new Westech Dyno! I first found out about the chassis dyno when I read this great post from John. Before list the posts, check out John's awesome Cobra Build Website! MY427SC.COM

Ryo is bringing the HOC 359 and I am bringing the CHP 383. We will attempt to dial in our carb jetting and possibly air bleeds, as well as setting the timing for maximum HP thrills. Price is $125 an hour with most cobras taking 1-2 hours. Here is a little more info on Westech. Here is their ad for the chassis dyno. I'll have the digital camera in hand and will have the full story when we return. I'm hoping for 425 at the wheels...maybe 450 if I get really lucky. I am anxious to see all the machines and computers and also anxious to compare these results to Dyno2000.