How long do the original timing chains last on a typical non-abused 1970 LS-5? How do I know when a new chain/gears should be installed (obviously before it breaks)? How can I test the degree of wear/slack?
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Tony -
Re: Timing Chain Replacement
Tony, from the questons you've asked, I assume you are contemplating some makor engine work or a long drive. I would look seriously at any timing chain that gone over 100,000 miles. Rather than try to assess the condition of the one you've got, You can replace it in the same amount of time. I have heard of trying to assess the timing chin condition by reversing the crank rotation and measuring the degresse of rotation in the crank before the distributor moves, but I don't remember what the acceptable limit is, my standing rule on all my old cars is if in doubt, the timing chin is the first thing to replace. It's also a great time to replace the timing cover seal which is usually leaking on a car that old. The timing chain and the rear axle bearings on a c-3 are the things most likely to strand you on the road in a manner that can't be repaired quickly. -
Re: Timing Chain Replacement
Tony, from the questons you've asked, I assume you are contemplating some makor engine work or a long drive. I would look seriously at any timing chain that gone over 100,000 miles. Rather than try to assess the condition of the one you've got, You can replace it in the same amount of time. I have heard of trying to assess the timing chin condition by reversing the crank rotation and measuring the degresse of rotation in the crank before the distributor moves, but I don't remember what the acceptable limit is, my standing rule on all my old cars is if in doubt, the timing chin is the first thing to replace. It's also a great time to replace the timing cover seal which is usually leaking on a car that old. The timing chain and the rear axle bearings on a c-3 are the things most likely to strand you on the road in a manner that can't be repaired quickly.Comment
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Re: Timing Chain Replacement
Tony----
Many original timing sets from the sixties and seventies used an aluminum cam sprocket with nylon teeth. This was used to reduce engine noise, but is a short-lived piece. These begin to deteriorate after about 50,000 miles and are usually in sad shape by 100,000. If yours is the original, even with a lesser number of miles, the age factor may play into the deterioration of the nylon teeth. Usually, there are 2 factors that indicate wear. The first is timing chain noise which usually manifests itself as an irregular "rattling" sound. When the chain and/or sprocket teeth are really bad, the chain starts hitting the cover and the noise increases substantially.
The second, more subtle, indication of timing set wear occurs when timing the engine with a timing light. If the timing mark on the balancer seems to "jump around" while timing the engine, the timing set is deteriorated. A new timing set will produce a "rock steady" timing mark.
While I usually recommend and use only GM parts, the timing set is an exception. For the timing set I recommend and exclusively use the premium, Cloyes Tru-Roller timing set. The ONLY way to go!In Appreciation of John HinckleyComment
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Re: Timing Chain Replacement
Tony----
Many original timing sets from the sixties and seventies used an aluminum cam sprocket with nylon teeth. This was used to reduce engine noise, but is a short-lived piece. These begin to deteriorate after about 50,000 miles and are usually in sad shape by 100,000. If yours is the original, even with a lesser number of miles, the age factor may play into the deterioration of the nylon teeth. Usually, there are 2 factors that indicate wear. The first is timing chain noise which usually manifests itself as an irregular "rattling" sound. When the chain and/or sprocket teeth are really bad, the chain starts hitting the cover and the noise increases substantially.
The second, more subtle, indication of timing set wear occurs when timing the engine with a timing light. If the timing mark on the balancer seems to "jump around" while timing the engine, the timing set is deteriorated. A new timing set will produce a "rock steady" timing mark.
While I usually recommend and use only GM parts, the timing set is an exception. For the timing set I recommend and exclusively use the premium, Cloyes Tru-Roller timing set. The ONLY way to go!In Appreciation of John HinckleyComment
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Re: Timing Chain Replacement
Bill and Joe,
Thanks for your "timely" input! I am planning a trip to Boston (~800 miles one way) for the July regional and I want to make sure I get there in one piece and no delays of the mechanical nature. My 1970 Corvette has about 96,000 miles on it and I believe the engine has never been "operated" on other than replacement of water pump in 71 and oil pan in 72. Of all my recent questions, I think a new timing chain will probably be the best investment I can make prior to this trip. The timing does seem to wander around a bit when I last did the timing.
TonyTonyComment
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Re: Timing Chain Replacement
Bill and Joe,
Thanks for your "timely" input! I am planning a trip to Boston (~800 miles one way) for the July regional and I want to make sure I get there in one piece and no delays of the mechanical nature. My 1970 Corvette has about 96,000 miles on it and I believe the engine has never been "operated" on other than replacement of water pump in 71 and oil pan in 72. Of all my recent questions, I think a new timing chain will probably be the best investment I can make prior to this trip. The timing does seem to wander around a bit when I last did the timing.
TonyTonyComment
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Re: Timing Chain Replacement
Joe,
Thanks for the recommendation on timing set. Where can I get this premium Cloyes Tru-Roller timing set that you recommended in above post? Is this "set" all I need for this job? Any special tools/skills needed tackle this job myself? Briefly, any special concerns or notes or pitfalls to avoid to help make this a successful job? Thanks again for all the input!
TonyTonyComment
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Re: Timing Chain Replacement
Joe,
Thanks for the recommendation on timing set. Where can I get this premium Cloyes Tru-Roller timing set that you recommended in above post? Is this "set" all I need for this job? Any special tools/skills needed tackle this job myself? Briefly, any special concerns or notes or pitfalls to avoid to help make this a successful job? Thanks again for all the input!
TonyTonyComment
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Re: Timing Chain Replacement
Tony, try Summit racing for the Cloyes timing chain & gear set. Their Part Number for a big-block is CLO-9-3310 price is $ 78.95 free shipping on orders over $50. 1-800-230-3030 from the latest catalogue-prices good thru end of June '99 Don't forget a gasket set, timing cover and pan just in case . Timing cover set should contain the front seal. Don't forget the grease for the rear axle Bearings. Have a good trip.Comment
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Re: Timing Chain Replacement
Tony, try Summit racing for the Cloyes timing chain & gear set. Their Part Number for a big-block is CLO-9-3310 price is $ 78.95 free shipping on orders over $50. 1-800-230-3030 from the latest catalogue-prices good thru end of June '99 Don't forget a gasket set, timing cover and pan just in case . Timing cover set should contain the front seal. Don't forget the grease for the rear axle Bearings. Have a good trip.Comment
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Re: Timing Chain Replacement
Tony----
You can obtain the Cloyes Tru-Roller timing set from most automotive performance vendors. Performance Auto Wholesale in Chatsworth, CA (818-678-3000) is one that offers good prices and there are many others. The Cloyes set that you want is their number 9-3110. Actually, Cloyes makes the identical sets for sale under other major brand names. Howver, "others" also make "copy-cat" sets for sale under major brand names. I accept ONLY Cloyes.
The other parts that you will need are timing cover gasket(GM #10114142), water pump to block gaskets(GM # 3860039----you must remove the water pump), oil pan gaskets (GM #10159519---you must remove the oil pan)and, while you're at it, you should replace the front cover oil seal(GM #10191640), so you'll need that, too.
As far as special tools go, you'll need an harmonic balancer puller and a puller to remove the crankshaft timing sprocket. Otherwise, normal hand tools, INCLUDING A GOOD TORQUE WRENCH will suffice.
As far as "special instructions" go: first, make sure that the timing set is properly installed and the marks lined up EXACTLY(or you'll be going "back in"). Check the harmonic balancer seal surface for grooving. If grooved, install a repair sleeve or, better yet, a new balancer.In Appreciation of John HinckleyComment
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Re: Timing Chain Replacement
Tony----
You can obtain the Cloyes Tru-Roller timing set from most automotive performance vendors. Performance Auto Wholesale in Chatsworth, CA (818-678-3000) is one that offers good prices and there are many others. The Cloyes set that you want is their number 9-3110. Actually, Cloyes makes the identical sets for sale under other major brand names. Howver, "others" also make "copy-cat" sets for sale under major brand names. I accept ONLY Cloyes.
The other parts that you will need are timing cover gasket(GM #10114142), water pump to block gaskets(GM # 3860039----you must remove the water pump), oil pan gaskets (GM #10159519---you must remove the oil pan)and, while you're at it, you should replace the front cover oil seal(GM #10191640), so you'll need that, too.
As far as special tools go, you'll need an harmonic balancer puller and a puller to remove the crankshaft timing sprocket. Otherwise, normal hand tools, INCLUDING A GOOD TORQUE WRENCH will suffice.
As far as "special instructions" go: first, make sure that the timing set is properly installed and the marks lined up EXACTLY(or you'll be going "back in"). Check the harmonic balancer seal surface for grooving. If grooved, install a repair sleeve or, better yet, a new balancer.In Appreciation of John HinckleyComment
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Re: Timing Chain Replacement
Tony, I have a 71 LS5 with 111K original miles, and it's currently having the timing chain replaced. It was still quiet, but I did notice some "movement" of the timing mark as I tried to set the timing. At that mileage, I figure that replacement is cheap insurance. The mechanic hasn't gotten into it yet, so I cannot be sure whether the cam sprocket is nylon-faced or not. I have heard diffierent opinions regarding the use of nylon gears on big blocks, so I'll post as soon as I know.
Regards, Nick 71 LS5Comment
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Re: Timing Chain Replacement
Tony, I have a 71 LS5 with 111K original miles, and it's currently having the timing chain replaced. It was still quiet, but I did notice some "movement" of the timing mark as I tried to set the timing. At that mileage, I figure that replacement is cheap insurance. The mechanic hasn't gotten into it yet, so I cannot be sure whether the cam sprocket is nylon-faced or not. I have heard diffierent opinions regarding the use of nylon gears on big blocks, so I'll post as soon as I know.
Regards, Nick 71 LS5Comment
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