'85 Timing Chain replace
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Instructor
Joined: May 2002
Posts: 223
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From: Oklahoma City Oklahoma
'85 Timing Chain replace
A friend of mine with an '85 coupe had his cam gear on his timing chain shear off it's PLASTIC teeth. The car had 160K or so miles on it and he ended up replacing with a crate motor. My '85 coupe has 125K miles and I feared the same scenario, so this week I tore into the L98 and replaced the timing chain & gears, water pump, harmonic balance,(it was coming apart) and the hoses. The timing chain cover replace was a wrestling match to say the least, but my friend and I got it done. Now, I haven't posted on here in some time, so sorry if this is old fodder, but I have one honest question. Why in the heck did the General see fit to use aluminum with PLASTIC teeth for such an important part of their engine as the cam gear on the timing chain. Further, I have an almost new 305 Vortec crate motor that i'm about to put in a streetrod pickup I'm building. Does it have a self destructing cam timing gear on it too??? Thanks,
danny
danny
Safety Car
Joined: May 2003
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From: [Quote=WOEII] Is dried brown doodie powders man! [/Quote]
Metal Gear - $1.25
Plastic Gear - $.125
Having your pistons smash your valves at 5000 RPM - Priceless.
Don't know the answer to your other query but for the price of a few gaskets you could always check before installation.
Plastic Gear - $.125
Having your pistons smash your valves at 5000 RPM - Priceless.
Don't know the answer to your other query but for the price of a few gaskets you could always check before installation.
Burning Brakes
Joined: Feb 2000
Posts: 927
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From: Saginaw TX
All manufacturers have used them. They are quiet.... that is until they come apart. I have one strip on a 440 Mopar on the day it turned 100K. It was a 4 speed and had a pretty healthy clutch. It also had a worn out thrust bearing on the crank and crank was moving quite a bit. My 86 Corvette had a nylon cam gear, but will be receiving a double row roller when it goes back together. Would use a belt drive, but them babies are just too expensive.
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
[QUOTE=mash557]All manufacturers have used them. They are quiet.... QUOTE]
That's the only reason I've ever heard for them. People equate a quiet, smooth running engine with quality and Detroit was always ready to satisfy. You know, of all of the multitudes of cars I've owned in 30+ years of driving, the quietest engine I ever had was a flathead six in a 56 Plymouth. At idle, it was literally so quiet and smooth that if standing outside of the car, you had to put your hand on the car to tell if it was running. I'm really doubting that IT had a freakin' %$@&#! plastic cam gear!
That's the only reason I've ever heard for them. People equate a quiet, smooth running engine with quality and Detroit was always ready to satisfy. You know, of all of the multitudes of cars I've owned in 30+ years of driving, the quietest engine I ever had was a flathead six in a 56 Plymouth. At idle, it was literally so quiet and smooth that if standing outside of the car, you had to put your hand on the car to tell if it was running. I'm really doubting that IT had a freakin' %$@&#! plastic cam gear!
Instructor
Joined: Aug 2004
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with all of the above. The reason it's done is because it is quiet, or quieter. I also had a timing gear replaced on a 440 Mopar at high mileage, but I lost one on a 360 Mopar at lower mileage because it had a fast cold start 'racing' idle. 
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
I replaced the timing set in mine, this spring, because I discovered 12* of slop in my rotor movement. The plastic/aluminum cam sprocket was in pristine condition after 160,000 miles, no chips or cracks. The slop was all in the stretched chain.
That '56 Plymouth probably had timing gears. And likely the cam gear was made of fiber for the same reason as our plastic coating. They were at least as troublesome.
RACE ON!!!
That '56 Plymouth probably had timing gears. And likely the cam gear was made of fiber for the same reason as our plastic coating. They were at least as troublesome.
RACE ON!!!
