Timing Cover

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   In the middle of rebuilding my '78 258.  Put the timing gears on tonight and the timing cover will not go on.  The cam sprocket bolt is sticking out too far for the cover to seat all the way down.
Closer inspection of the cam sprocket against the old one and it appears that while the teeth and overall thickness of the sprocket is the same the new gear isn't as "deep" on the inside allowing the washer and bolt to seat in far enough for the cover to go on.  I put the old gear on and the cover goes on fine.

I've found the old style gear on eBay, and can probably just order one.  However it has the nylon teeth and would rather use the new gear which is all metal.

Any thoughts?

Tom

Edited by tloftus - Nov/17/2019 at 8:11pm

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tloftus Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Mar/18/2008 Location: Sioux City, IA Status: Offline Points: 296	Post Options Post Reply Quote tloftus Report Post Thanks(0) Quote Reply Topic: Timing Cover Posted: Nov/17/2019 at 8:09pm
	In the middle of rebuilding my '78 258. Put the timing gears on tonight and the timing cover will not go on. The cam sprocket bolt is sticking out too far for the cover to seat all the way down. Closer inspection of the cam sprocket against the old one and it appears that while the teeth and overall thickness of the sprocket is the same the new gear isn't as "deep" on the inside allowing the washer and bolt to seat in far enough for the cover to go on. I put the old gear on and the cover goes on fine. I've found the old style gear on eBay, and can probably just order one. However it has the nylon teeth and would rather use the new gear which is all metal. Any thoughts? Tom Edited by tloftus - Nov/17/2019 at 8:11pm
	1966 AMC Rambler American Rogue - 232 I6 http://theamcforum.com/forum/1966-amc-american-rogue_topic20995.html 1978 AMC AMX - 258 I6 http://theamcforum.com/forum/1978-amc-amx_topic62333.html

FSJunkie Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742	Post Options Post Reply Quote FSJunkie Report Post Thanks(0) Quote Reply Posted: Nov/18/2019 at 2:38am
	The nylon cam gear looks stupid but in actual practice they last well past 100,000 miles. I've seen them still going with close to 200,000 on them. I did not run into this problem when I installed a new steel cam gear in my 1977 and 1984 sixes. Their cam bolt cleared the timing cover no problem. Perhaps you got a low quality cam gear.
	1955 Packard 1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19677	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Nov/18/2019 at 6:07am
	How much difference is there? If it just needs a little clearance you could carefully grind the hub of the gear down a little in back. It doesn't have to be perfectly flat there, but if concerned about that could take it to a machine shop to be surfaced. Take the old gear and match the measurement. It can't be off much or there would be an issue with the crank gear also. Should be no more than 1/16" off (0.0625"). 0.040-0.060" off shouldn't make a difference in the chain, you'll have to measure the two hubs and see if that's enough. The bolt and cam shouldn't expand more than 0.010-0.020", so 0.030" or so clearance should be adequate.
	Frank Swygert

tloftus Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Mar/18/2008 Location: Sioux City, IA Status: Offline Points: 296	Post Options Post Reply Quote tloftus Report Post Thanks(0) Quote Reply Posted: Nov/18/2019 at 8:03am
	When I install the new cam gear it is very close to the block. It may even be touching but when I compare the two the rear recesses appear to be the same. On the old one the front is "dished" out more than the new one, allowing the washer and bolt to sit in further and allow the timing cover to clear. When I put the new one on and torque down the bolt, the timing cover actually rocks on the bolt, I would say there is a good 1/16" gap between the cover and the block. I could grind off the back but if the cam is bottomed out in the recess (I think it is) then grinding off the back might work by allowing the cam to go further into the block. Headed back to the parts store to see if they have another one, maybe this one is defective. If that doesn't work I'll probably just buy the nylon one.
	1966 AMC Rambler American Rogue - 232 I6 http://theamcforum.com/forum/1966-amc-american-rogue_topic20995.html 1978 AMC AMX - 258 I6 http://theamcforum.com/forum/1978-amc-amx_topic62333.html

Heavy 488 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3553	Post Options Post Reply Quote Heavy 488 Report Post Thanks(0) Quote Reply Posted: Nov/18/2019 at 8:30am
	Replace it. China strikes again? Start cobbling on the back side all you need is gear wobble.

tloftus Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Mar/18/2008 Location: Sioux City, IA Status: Offline Points: 296	Post Options Post Reply Quote tloftus Report Post Thanks(0) Quote Reply Posted: Nov/18/2019 at 8:44am
	I went back to the parts store -- the gear they had in back was (as expected) exactly the same. I guess it's possible there is a bad batch or something but there's no way anyone got this to work without either a thinner washer or modifying the gear itself. I just don't see how it could ever work. I've ordered the nylon gear and will use it. Guess it will be an unsolved mystery. Thanks, Tom
	1966 AMC Rambler American Rogue - 232 I6 http://theamcforum.com/forum/1966-amc-american-rogue_topic20995.html 1978 AMC AMX - 258 I6 http://theamcforum.com/forum/1978-amc-amx_topic62333.html

Heavy 488 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3553	Post Options Post Reply Quote Heavy 488 Report Post Thanks(0) Quote Reply Posted: Nov/18/2019 at 9:07am
	You could also look into a stock replacement for a Jeep 4.0. it's a single roller.

Trader Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6884	Post Options Post Reply Quote Trader Report Post Thanks(0) Quote Reply Posted: Nov/18/2019 at 12:18pm
	The S388 is the same casting number for Enginetech, Melling and Cloyes (C3035). The Seal Power KT3493S gear has the recess for the washer.

tomj Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544	Post Options Post Reply Quote tomj Report Post Thanks(0) Quote Reply Posted: Nov/18/2019 at 8:06pm
	i just changed the timing set in my 199 a couple weeks ago. the original plastic gear, 198,000 miles. noticable wear on the teeth, chain slack, still quite a ways from failure. i have nothing else to offer here, other than i got a Mahle kit, i think it was, with the repair sleeve. all steel sprocket, no clearance issues. the rear is of course recessed with the locating pin. what exactly is hitting? dab some paint on various places and check.
	1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19677	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Nov/19/2019 at 6:27am
	My best guess is that you probably are getting a 4.0L timing gear. Someone collapsed a catalog and spec'd the newer part as fitting all. This happens a lot, and often small things like that dish are missed. A newer timing cover might solve the issue, but I'd just get the nylon covered gear or a different manufacturer that fits correctly, such as the Sealed Power gear Trader mentioned. The newer timing covers have larger bolt holes in some places due to a difference in how accessories were mounted (I believe 74 and newer). There are enough bolts the same size as the older ones that it will align correctly on those, washers on the larger holes. Bolt pattern is the same.
	Frank Swygert