Cam question

[ITLBOK333]

So it looks as though I have cam walk in my newly rebuilt 360. It tore up my distributor gear. Im reading that this is a problem with 360 rebuilds. My question is this, do I have to replace my cam now, I already got a new distributor, but now I have to fix the cause, does anyone know if it could be that the cam was installed improperly, or is the cam dead. If it is dead and I need to get a new cam kit, any suggestions on which cam kit to buy? I was looking into the Edelbrock one, since I have a Edelbrock intake. Thanks

[carrotman]

According to the 76 TSM, camshaft endplay is maintained by the load placed on the camshaft by the oil pump and distributor drive gear. I would assume that the metal of the distributor gear is softer than the cam gear. Could the distributor have been installed wrong? Do you have any type of warranty on the rebuild?

[Knucklehead]

The cam is kept in place by the load placed on it by the lifters and the taper of the lobes. The taper 8 lobes is towards the rear and the taper of the other 8 is towards the front. This taper is also what ratates the lifter in its bore.

Roller cams require an retainer and/or button to keep them from walking as the lobes are flat with no taper.

Is you cam "flat"?

[Al Johnson]

Another possible explanation for your distributor gear failure is the timing set. Dynagear Corp was making Edelbrock and their own roller chain timing sets for AMCs. They had a bad casting setup, and the cam sprocket did not have the oiling passage all the way through the hub. There should be two "slots" inside the cam sprocket hub: one is square, for the keyway. The other is half-round, and is the oil passage. The oil passage HAS to go all the way through the hub, or no pressurized oil gets to the fuel pump eccentric or the distributor/oil pump gears. There will also be darn little oil to the timing chain, but the first thing to fail will be the distributor gear.

[Chero77]

Another possible cause is the cam itself. A substantial number of cam blanks have one journal that is about .100 wider than stock. (I think its the third journal--don't remember off hand.) This causes the cam to walk towards the front of the engine destoying the distributor gear. You need to closely compare your cam to the stock factory cam. The difference in journal width on the bad blanks is apparent to the naked eye, however I would measure each journal with calipers and compare to stock.

Aftermarket cams with out-of-spec journals and cam sprockets that are missing the oiling slot are common problems on AMC engines. You must check these parts personally. Most rebuild shops are not aware of the defects. For more info, do a search here and on the AMC boards. These problems are well known.

Anyway, I would pull the cam and check it. Also, check for the oiling slot in the cam sprocket as well.

[billyrb]

Chero77 is correct. The cam itself was made incorrectly. If you bought it from Summit, Jegs, or one of several other places, they'll replace it for free.

Crane Cams & P.A.W. in CA. have had good cams thus far. The cam I currently have is a PAW and doesn't have the cam-walk problem. The cam I am changing to (H-260-2 Crane Cam) also doesn't have this problem. Check into both of those.

As for the oiling slot in the cam gear, I was one of the first to experience this. The machinist was building my short block, and a well-known AMC engine builder buddy of his happened to stop by, and instantly noticed the 360. They looked at it, and the AMC builder pointed out the cam-gear slot not being drilled all the way through. Here is a link to the original post:

Timing Gear Oiling Problem (http://www.ifsja.org/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=2;t=009595)

I hope this helps out.

[ITLBOK333]

Thanks for all the input, my rigs at the shop right now, they are working on it, I will mention the above and see what they come up with! Thanks again all.

[mark barton]

YOU CAN ALSO INSTALL A ANTI-FORWARD CAM BUSHING,

IT IS A PLASTIC CAM BUTTON THAT INSTALLS ON THE CAM BOLT AND KEEPS THE CAM FROM WALKING.

GO TO THE AM RACING WEB SITE AND LOOK UNDER ENGINE PARTS.

[chrisnsarah]

You got me worried now about the timing sets. I got a miloden roller chain from PAW. Should I worry?

[Al Johnson]

Originally posted by chrisnsarah:
You got me worried now about the timing sets. I got a miloden roller chain from PAW. Should I worry?No need to worry at all. The problem timing sets were made by Dynagear. If your engine is not together, just look in the cam sprocket hub for the oil passage, make sure it's open all the way through. If it's assembled, well, no need to worry now, 'cause worry won't help. It's good or it's bad, nothin to do about it now.
:D
Al

[billyrb]

Mark, the anti-forward cam bushing will only really work on a standard cam that is made correctly. It is made to take up for the loss of minor tolerances of older engines. The major cam-walk problem that has been discussed here over the last year or so is due to camshafts that have been made incorrectly. As of the manufacturing defects, the cam jumps VIOLENTLY forward 1/2" at a time. No bushing, button or part will correct this for a cam that was made wrong.

Now, having said this, on a good cam in an older engine, the parts you mention will work wonderfully. For more info, you can talk to Randy Guynn at Performance American Style (http://www.performanceamstyle.com)

[kellysguy]

Which cam manufactures had this problem and which pt #s?