First the Carter BBD on my supersix gives up the ship, then I rebuild two only to have one work (the other has a warped throttle body....I have a couple more to frankenstein into 'useable' carbs, I think...).



I checked some basics tonight and found I have wiped out the Mopar Performance 4 degree bushing in my double roller chain cam gear....




the bushing is egged badly, the gear was torqued to spec when I pulled it off (checked before I pulled it). The timing chain cover has a slight radial scratch on it from gear contact front and top. It looks like the dowel also slipped out of the hole and egged the gear hole at one time, but the dowel was in the bushing when I pulled the setup.

I would like to drill the cam and install another dowel (180 degrees from the stock dowel)to help keep the 'force' off the bushing/or find a harder set of bushings to reinstall so I can get my Feather back on it's feet....


Not good for a mill with only 15K on the rebuild....

anyone have a good solution? I figure now the time to get ready to put in a cam stop button too, maybe...

Geeezzz...

also as an FYI, I'm using a Melling oil pump with the 7/8" rotor, and the plastic distributor gear is intact and perfect....


at least I wasn't at 6K trying to get a good shift when it cut loose...

-D.Idiot

thats freaking crazy man!! I wonder how in the heck that could happen?? maybe the cam decided to "walk" on you? i'll definatly be installing a cam stop in my motor!

Justin

Mopar Performance quality strikes again! Dosn't Cox Brothers have a timing chain kit? Or Cloyes? Screw MP, the lack of quality I have personally seen and heard about convinced me to never get anything from them.

My gear is stamped S338, so it's a 'cloyes', but it came in a 'DynaGear' box. I don't need the whole set, I just need to replace the bushing and make sure that there's something to take up the load on the bushing so it doesn't happen again...and I'll have to add a cam stop to keep the gear/chain from contacting the timing cover.

Jeez, wish I could just put the gear on correctly and just fill the hole with Ni-rod to fix it for good...


-D.Idiot

When I drill the bushing hole, I drill a 'blind' hole. I only drill the hole deep enough for the bushing thickness. It will leave a counterbore for the bushing to bottom out in, and so it is more 'captive.'

_________________
'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Wish I could do that, but the bushings are almost as thick as the gear at that point (blindhole might leave about .010" of meat).

I just drilled my cam and added another dowel to 'take up' the load and some interesting things came up that 'weirded' me out....

The scrape marks on my timing chain cover suggest that the cam walked forward enough to scrape the gear on the cover and leave a nice radiused scrap across front of the cover. Also I could shove the cam back into the block a bit when I pushed on it. I pulled out my spare double roller chain timing set and compared the gears, and noticed that the new gear matched the old gear when I aligned the teeth *and* the hole in the offset bushing(the intact part) . Since I have the cam and crank stuck at TDC on the money, and both haven't moved out of alignment, I figured I could plug the new gear in without having to drill it for another bushing (famous last words).

I ruined two carbide bits (need to get some cobalt ones...) but came up with a second dowel to take some thrust of the stock cam dowel.




Using my Journeyman layout skills I determined the centerline of the dowel hole and cam gear and located another hole 180 degrees opposite the stock hole. Installed the gear and cam bolt with a 'short' washer to hold it in place at torque spec with the chain on. Using the gear as a template I added the other dowel...





Another couple of 'hinky' details that were 'odd', was:
1)the stock cam dowel is 7/32", and the stock hole in the gear is 1/4", I noticed this is enough play to allow the gear to have some 'slack' (not much, but 1/32" can be a slight 'burp' in timing).
2)since the cam bolt isn't the same size as the center of the gear, this can allow the gear to 'float', if the cam walks back and forth (placing stress on the gear, and could explain a few things with my bushing problem).

I followed doc's advise and have my timing cover located and drilled, tomorrow I'll get a nut and washer welded onto my cover, and I have a spare pushrod that I can cut and thread to make a cam stop.

sheesh, what a teething problem...at least the 1974 'road oiler' Duster still clicks along, but it's hard to go back to a car with a tired slant and 2.76 gearing....

Thanks for the tip bud, I'll try that if this fails to work.

-D.Idiot

No need to do this, just use a rocker arm adjustment screw as the stop.

BTW, great handywork on the fix, DI
What a goofy failure, this is not a common problem.

My bet is you will make sure everything is super tight when it goes back together. You may also want to use a larger washer under the cam gear bolt to be sure the dowel pin and bushing are covered.
DD

For some reason, my cam bolt has a large washer, and it covers both pins adequately, which I feel will keep some pressure on the 'new' dowel in case it decides to 'make a move'.

Luckily I have some rocker studs laying around, so I'll use one of them.


Thanks, Doc!

-D.Idiot

I got my cam stop fabbed up, and tonight I installed the cover back onto the assembly....so if all goes well, tomorrow afternoon I should be able to drive my car again, and hopefully not worry about that ever happening again for 100+K....


Thank You!

-D.Idiot