Timing Chain and sprockets
Thread Starter
Instructor
Joined: Aug 1999
Posts: 122
Likes: 1
From: Averill Park NY
Timing Chain and sprockets
70 big block. Car died (close to home) and with some good neighbors and friends got it pushed into the garage. The general diagnosis by committee was timing chain jumped the sprockets. Tore it down (damn the shroud) and sure enough the chain was very loose and the sprockets (especially the cam nylon) was what could hardly be classified as a sprocket. This is a street car, any thoughts on the replacement chain and sprockets. How about thoughts on the cam dowel bushings to advance the cam slightly in anticipation of chain stretch. Thanks in advance.
Lee :confused:
Lee :confused:
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Timing Chain and sprockets (Lee70454)
If it jumped a tooth I would pull the heads and check your valves, might have bent a few. A double roller or at least a steel chain and gears would be the way to go. Were those engines built with nylon tooth gears as stock? Is that the orig engine?
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Re: Timing Chain and sprockets (Lee70454)
Cloyes roller chain. Cam advance/retard notched into gear if necessary. Good quality and inexpensive... I would not change cam timing.
OH YEAH.... love that fan shroud :mad :mad
Eddie
OH YEAH.... love that fan shroud :mad :mad
Eddie
Thread Starter
Instructor
Joined: Aug 1999
Posts: 122
Likes: 1
From: Averill Park NY
Re: Timing Chain and sprockets (Fevre)
It is the original engine and asking others more knowledgeable than I, it came with a steel covered in nylon gear (noise reduction). I have pulled the valve covers, spark plugs and slowly turned the engine over and the valve asembly in motion appears to be ok. Again, anyone out there with knowledge on the potential valve clearance on this please let me know. Fevre, thanks for yuor input.
Drifting
Joined: Jul 2001
Posts: 1,418
Likes: 1
Re: Timing Chain and sprockets (Lee70454)
Lee,your factory cam has some advance ground into it. Best leave it as is IMO
In your particular case a Link Belt design chain and gear set from Cloyes would be my choice since the motor is stock ect.Part # is C3024XSP. It is a HD chain and will last a very long time so with this one install as normal without 3 keyways to mess with
In your particular case a Link Belt design chain and gear set from Cloyes would be my choice since the motor is stock ect.Part # is C3024XSP. It is a HD chain and will last a very long time so with this one install as normal without 3 keyways to mess with
Le Mans Master
Joined: Aug 2000
Posts: 6,362
Likes: 7
From: Brazos TX
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Timing Chain and sprockets (Lee70454)
Do you run the engine hard? A lot of redline shifts? If so I would recommend a double row full (or true) roller chain. It should be a high quality one with non-split rollers. If its not driven hard you can go with a split roller. I wouldn't get anything less than a full roller because they help reduce friction and stretch.
Burning Brakes
Joined: Dec 2000
Posts: 962
Likes: 0
From: Carlisle PA
Re: Timing Chain and sprockets (mountainmotor)
Lee,your factory cam has some advance ground into it. Best leave it as is IMO
In your particular case a Link Belt design chain and gear set from Cloyes would be my choice since the motor is stock ect.Part # is C3024XSP. It is a HD chain and will last a very long time so with this one install as normal without 3 keyways to mess with
In your particular case a Link Belt design chain and gear set from Cloyes would be my choice since the motor is stock ect.Part # is C3024XSP. It is a HD chain and will last a very long time so with this one install as normal without 3 keyways to mess with
What Mountainmotor said :yesnod:
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Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Timing Chain and sprockets (mountainmotor)
mountainmotor
What is your take on degree the cam after timing belt change? I have read that should degree it whenever you change the belt or crank for that matter since there are diff tolorances from diff manufacturers. Or is that just for racing so you can squeeze every last horse out of the engine?
thanks
BTW That was my block Greg got for his car. It had the 72 ZR-1 stamp but he was told it was a newer block restamped but it was in a 73 vette so I have no idea why someone would retamp it and put in a 73.
What is your take on degree the cam after timing belt change? I have read that should degree it whenever you change the belt or crank for that matter since there are diff tolorances from diff manufacturers. Or is that just for racing so you can squeeze every last horse out of the engine?
thanks
BTW That was my block Greg got for his car. It had the 72 ZR-1 stamp but he was told it was a newer block restamped but it was in a 73 vette so I have no idea why someone would retamp it and put in a 73.
