degree in camshaft and cam break in
All aftermarket camshafts available for the nailheads must be degree’d in. stock replacement cams however are designed to just be installed “straight up.” you can degree your cam in via offset cam keys which can be purchased online or from your local machine shop, but it's encouraged to just use the roller chain sets that we offer, even with a stock cam that you don't have to degree in as the quality is way better than the stock chain and gear set, much less the inferior quality overseas made chains that are available now. The roller chain set crank gear consists of a straight up setting, advanced 2,4,6,and 8, as well as retard 2,4,6 and 8.
Tools that will be needed are a dial indicator, a long wrench for the crank bolt, a piece of flat stock or a wrench used for the “positive stop,” and your cam degreeing kit, that should include a hollow tube/pushrod, solid lifter, degree wheel and pointer.
To degree in a camshaft, all the recorded opening and closing figures at .050” are contingent upon your top dead center labeling being correct. .050” is the standard used as a measuring point, as the valve doesn't even really start moving until then. To start, install your adjustable roller chain set “straight up” with cam sprocket mark pointing straight down, the inner white dot on the crank key and outer white dot pointing straight up to the cam sprocket mark. Top dead center can be found just as easily with or without the head on, but if the head is on, you need an extra tool to stick in the spark plug hole that can consistently be used to measure for the positive stop. Just like the opening and closing figures being recorded at a measurable point, locating top dead center must also be recorded using actual points that are measurable, as the piston is at the top of the hole for X amount of degrees contingent upon variables such as rod length.
To find top dead center, start by guessing. With the #1 piston at the top of the hole, and pointer installed via a timing cover mounting bolt on the front of the block. tighten the crank bolt over the degree wheel with an impact gun, with the TDC line on the wheel, lined up with the pointer. Your mark will likely move when you tighten it down and thats perfectly fine. Now rotate the crank to the left or the right. It does not matter. Bolt a wrench or any other flat object over the top of the cylinder after the piston has receded down into the hole, with 7/16 coarse thread bolts. After tightened, now rotate the crank in one direction until piston face bottoms out into the object you have bolted over the cylinder. Mark on the wheel, the point in which the piston bottomed out. Now rotate the bottom end, the other direction until the piston bottoms out again. Mark the wheel again. You will notice the recorded points of positive contact are not an even amount of degrees from the labeled TDC point on the wheel. Now, manipulate and bend the pointer needle on the front of your block, until the piston bottoms out an exact equal amount of degrees away from the tdc mark on the wheel, in both directions. For instance, if you read 4 degrees further on one end than the other, then recede the pointer 2 degrees, and then double check as many times as necessary until that figure becomes the same. It's imperative that this recorded figure is exact. You have now found the exact point of TDC! If you have a cylinder head bolted on, then the positive stop object would be a thread in unit installed in the spark plug hole. Although that is my preferred method of finding top dead center, another alternative is to use a dial indicator to measure an equal distance the piston recedes down in the hole from the same measurable point in both directions.
Now that you have found top dead center, you can remove the positive stop object from the block deck or spark plug hole. Now is the time to install the solid lifter on the intake lobe for the respective cylinder and install tube to simulate the pushrod. A hollow tube is ideal as the tip of your dial indicator which you will mount to the deck, will fit securely inside of it. Now record the .050” lift opening figure on the wheel. Rotate the engine counter clockwise at .050” lift to record the closing figure. Compare these recorded figures to the “degree in” information on the cam card. If the opening figure is -5 degree and closing figure is 38 degrees, and the degree in specs state opening figure is supposed to be -1 and closing figure is 34, then you know that you need to advance the cam 4 degrees via the labeled marks on the adjustable crank gear. Take it all back apart and adjust. Start over again with locating top dead center and measure your .050” figures all over again. A couple of degrees advanced is okay to compensate for chain stretch, although these roller chains don’t stretch much. Since you have to advance or retard in even number increments of 2, then always leave it a degree advanced if the required amount of advancing or retarding ends up being an odd number.
The next and final step is to double check your lobe center
Add the two opening and closing numbers noted
Add 180 to this sum
Divide this sum by 2
Subtract the smaller number of the two opening and closing numbers from this quotient.
Shown above is a typical cam card supplied with an aftermarket reground cam. Take note the degree in specs on the right, compared to the advertised specs on the left. This cam grind is a good mild cam for a nailhead. Very similar to what we call our “stage 1 cam,” except on a 112 LSA instead of 110. When regrinding camshafts, changing the LSA is very limited. Ideally 110-114 LSA is preferred. Wider end of the spectrum for larger cams. Take note the slightly longer exhaust duration which is ideal to overcome the restrictive exhaust passage over the top of the combustion chamber. On another note, make sure a cam grease (shown as an example) is used to rub into each individual cam lobe prior to cam install. This is to protect the cam long enough for thrown off oil from the crank shaft to lubricate and cool it. i have never flattened a cam in my entire career, regardless of any different cam and lifter combo.
cam break in:
Please take note that we use and sell the best lifters on the market. Although we prefer to use NOS, made in usa lifters whenever possible, we have never had cam and lifter failure with the cheaper lifters that we sell, either.
The break in process is critical. You can ruin a brand new flat tappet cam in just a minute. Engine oil MUST contain zinc (zddp/phosphorus) for a clinging protective barrier between high pressure points. The assembly grease used for cams is really only protection while you crank the engine to start it. The cam lobes on your cam do not directly receive oil from the pressurized oiling system. Meaning that, just because your oil pressure gauge is reading good oil pressure, it DOES NOT mean that your cam lobes and lifters are receiving oil. Oil is only supplied to the cam lobes and lifters (as well as rings, cylinder walls, wrist pins, fuel pump cam, distributor gear, timing chain, etc) at higher rpm, from being thrown off the crank/ crank rod bearing oiling holes. This means that the engine must maintain 2,000 rpm constantly upon engine start up for the first 30 minutes of run time. This 30 minutes of time does not have to be a consecutive 30 minutes. You can run the engine in 10 minute increments if you feel like it, as an example. Before starting your engine and after installing the distributor, you should static time your engine, so you are not messing with the timing while trying to start your engine. This will give you a baseline timing. You CANNOT idle the engine for even a minute during this period. That includes trying to set the initial timing with a standard timing light. A dial back timing light is best. Set your total timing that way, which is 30 degrees total at maxed out advance (stock and mild cams) with the vacuum advance disconnected. The oil the lobes receive from being thrown off the crank is not just for providing lubrication between the two mating parts which are new and do not match, with minimal contact area, creating excessive friction, but the oil is responsible for keeping the cam lobes cool, during this mating process, keeping the lobes from literally melting off. It is not necessary with any cam and spring sets that we sell to remove any of the valve springs during break in.
Break in of the cam, lifters and rings causes mild crank case contamination, by nature. Immediately after cam break in, the oil should be changed with a conventional 30 weight oil with zinc in it.
For a step by step article on engine break in, and instructions on setting static timing, please visit my blog www.nailheadbuick.com/blog. There also may be other articles on there that interest you. Thank you for supporting our small family owned business.
A side note: although its nice that the lifters rotate, they do not have to rotate, per as described in the factory shop manual. It is never recommended to put new lifters on an old cam. It is also recommended that engines are always broken in with a verified good working condition single carb set up that is jetted properly.
REMEMBER: DO NOT IDLE THE ENGINE FOR EVEN A MINUTE DURING THE FIRST 30 MINUTES OF CAM BREAK IN