Cadillac Timing Gear Problems

[jdotson]

I am currently running a 500 Cadillac direct drive with a 74" two blade Terminator. I am averaging about 30 to 40 hours run time before the timing gear on the crank explodes. I have just experienced this for the third time in a row. The motor has been completely rebuilt and a new crank installed in late summer of 2004. The last gear to fail was a true roller timing set. Is this a result of having direct drive and would a reduction box solve the problem? This motor is currently running at 12.5 to 1 compression with ported and polished heads, oversized valves and springs, and shaft mounted rocker arms at 1.72 ratio.

 

[BigBoom]

Purchase a Cloyes True Roller Timing Set, part # 9-3139. It's stronger than the stock gears. It can be purchased at a performace parts shop or Summit Racing online for $91.95. http://store.summitracing.com/default.a ... 497+300333
My engine has 35 hours on it with no problems. I know people who have hundreds of hours using these gears.

 

[jdotson]

The last timing set I tried was a Cloyes True Roller set from Cad Company. It didn't last long either. I also added a crank bolt and washer kit to be sure the hub wasn't walking and allowing the gear to move. I'm just wondering if the harmonics of the direct drive is busting the gear.

 

[Waterthunder]

The problem you are encountering also happens in very high performance standard transmission cars. The problem happens when you let of the throttle and a de revving load is transferred directly to your timing chain thru your crank. This never happens in an automatic car because the torque converter doesn’t transfer the load to the crank. If you have ever let off the gas in a standard car you felt the motor rev down. That’s why airboat motors and standard trany cars quickly stretch timing chains. I run gear drive any time a customer will spring for the additional cost. If you can’t locate a gear drive for a caddy you can reduce some off the load by controlling the (cam walk). Each time you de rev (let off the gas) on a motor the timing chain gets some slack on the load side. This slack allows the cam to walk forward thus putting a side load onto the rollers of the chain and gears. Chains are not designed for a side load so this wears out timing chains prematurely. Anytime you install a roller cam you must prevent the cam from walking or you will damage the roller lifters and all the rest of your motor. So we control the cam walk with what’s called a cam button. I set airboat cam end play between .010 to .020 thousands. After much experimenting I have found that cam buttons also increase the life of timing chains in cars equipped with standard trannies the same goes for airboats. I would try to find a gear drive first but if you can’t find one then install a cam button this will increase the life of your timing chain substantially. Also was your motor line bored when it was rebuilt if so you must run a shorter timing chain or it will wear out quickly.

 

[cowboy]

Killer post. Again!
keep it going waterthunder.

 

[jdotson]

Here's an update on the timing gear problem...turns out that the pulley hub on the crank has busted and the keyway fell out. The timing gear is intact but the chain is broke, possibly due to the hub failure. I'm still thinking this is a result of harmonics on the direct drive. My next step is to install an aftermarket viscous dampener to see if that fixes the problem.

 

[Waterthunder]

Since your already there I would recommend a cam button their less than $40 and will extend the life of your timing chain. Sounds like you got lucky I had a buddy who put one of those cheap Chinese balancers on a 400 SBC he came to find out it was a lot more expensive than a fluid damper. It did the same as yours the key way in the balancer cracked and the balancer flew off busting his crank snout and then it went thru his prop. If you do put a fluid damper on be careful how you install it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Don’t beat it on carelessly with a hammer. If you do you will pinch the vibration ring that floats inside the silicon.

 

[RJ]

Posted: Wed Feb 16, 2005 7:28 pm Post subject: caddy
Hay mon, what do you want to know about a cadillac? Go to my special spot and order their catalog and all and I mean all your questions will be answered. [url=http://WWW.CAD500PARTS.com]http://WWW.CAD500PARTS.com[/url] The tele. number is 505-823-9340
They are located in Albuquerque N.M. They are the best and with the most info. So until next question, keep that gas running and the exhaust hot. slow henry