Click on the pictures for a larger image.

For those who work on AMC engines, especially those who use them in high performance applications, it is not uncommon to see problems with the cam gear and distributor gear, which can cause serious problems with the distributor gear, the distributor shaft and valvetrain, since the mesh between the cam gear and distributor gear along with the pressure of the lifters on the cam is what keeps the AMC cam in place. These problems can be caused by a number of things, including wear, inadequate lubrication and slight machining irregularities. Some solutions have included cam buttons, requiring machining of the cover and tedious fitting, and anti-walk kits that install at the rear of the cam, which require the transmission to be separated from the engine if the cam is to be removed.

Fortunately, Nick Alfano has come up with a solution that is both elegant and effective. The kit requires only two small holes to be drilled into the block, and best of all, it will absolutely not affect any stock settings or function. I bought this kit in June, 2003 and installed it on my completed 401 longblock. Note that this kit will also install in the same fashion on any AMC engine after 1971.

The kit costs $210 for a standard double roller set, or $245 for a billet double roller set. The kit includes:

Standard Thrust plate kit: # AMCV8-TPC - price $210.00

Billet Thrust plate kit: # AMCV8-TPB - price $255.00

You will need: The first step is to place the template on the front of the block. It goes over the timing cover locating dowels. Actually, if your engine already has a timing set installed, the first step is to make sure that the timing marks are aligned, then remove the existing timing chain and sprockets.

The template is metal, painted in AMC blue. Classy!

Once the template is in place securely against the block, center punch the two marked holes, one above and one below the crank. This step isn't absolutely necessary, since the kit bits split point so they won't walk. Next, drill pilot holes using the 5/64" drill bit. Do not go deeper than 1/2" into the block, including the thickness of the template!! I strongly recommend using an adjustable drill stop or some other method of limiting the drill travel. Also be sure that the holes are being drilled parallel to and in line with the camshaft.

I used an adjustable drill stop (left). Note how it prevents the bit from going too deep (right). Note that this photo is for illustrative purposes only, since I masked off the cam and crank bearing areas to prevent metal filings from getting in.

After the pilot holes are drilled, switch to the #7 bit and final drill the holes, again not exceeding 1/2 inch depth. Now it is time for the tap. Use the lead tap (pointed end) first, then switch to the bottoming tap (flat end) to get the threads to the bottom of the holes. It's a real good idea to use good cutting oil, and to mask off the cam and crank bearings to prevent metal chips from getting in there.

The left picture shows the lead tap (left) and the bottoming tap (right). Go slow when tapping, frequently backing out to clear out the chips. You don't want to strip out your mounting holes! Note also the use of masking.

Once the tapping is done, clean all oil and metal chips out of both holes. If you haven't installed your cam yet, do it now. Place the thrust plate in place over the end of the cam and lightly snug down the two allen head bolts. The instructions say to apply Loctite and tighten them down now, but I was more cautious. I removed the keys from the cam to allow me put the cam sprocket in place and turn it to make sure there was no interference with the thrust plate. There is a little adjustment built in to the plate since the bolt holes are slightly oversize. Once that looked good, I replaced the keys, and installed the cam sprocket, the fuel pump eccentric and the distributor gear and torqued down the retaining bolt and washer to spec. The endplay/clearance to the thrust plate should be .004-.006, and the cam should turn freely. It that is all good, then remove the gear, eccentric and sprocket.

The left picture shows the thrust plate installed. I then test fit the cam sprocket. The right photo shows the difference between a regular double-roller sprocket (left) and the kit sprocket (right). The kit sprocket has been specially machined to account for the thrust plate. You cannot use a regular sprocket with this kit! Serious engine damage will result!

Once you are satisfied with the fit, tighten down both bolts. Remove one, place Loctite on it, and reinstall. Repeat with the other bolt. If you are working with a bare block, it's time to install the pistons, rods and crank, then install the kit timing set and go through the degreeing process. If, like me, you are dealing with an assembled block, install the kit timing set, making sure to align the timing marks. If you have already degreed the cam (like I did) make sure to use the same marks on the kit set as you used on the original timing set (straight up, advanced, or retarded). That's it!

The finished result. You can see the top allen bolt and part of the thrust plate through the cam sprocket.

The verdict? Well, I haven't installed the engine and fired it up yet, but the kit went in very easily and uses totally stock dimensions. There is no machining, grinding or other modification necessary aside from the two holes. If you decide to go back to the stock setup, just remove the thrust plate and put in a stock timing set. Is it worth it? Well, a good true double roller timing set is going for $90-100, and for me, the peace of mind that comes from knowing that I won't have to worry about my distributor gear getting munched - EVER - is worth the other $110. The kit is obviously well engineered, the pieces are well executed, and Nick has done a fine job of putting this kit together. All the hard work is done - all you have to do is drill and tap two holes. Nick's contact information is below - and tell him you saw it here!


Nick Alfano
262-308-1302 (day)
262-942-8271 (evening)
4849-76 St.
Kenosha, WI. 53142