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Hi folks, seems my timing chain is worn? Excessive Slack when one of the sides is tight. What would be the correct replacement with chain and sprocket. I see so many options on the internet. Just need something good but standard. This is a stock 1971 350 with hydraulic lifters. Don't necessarily want to spend too much either. Thanks
Actually, it doesn't look like excessive slack to me, but I think there is a description of how to measure the slack in the shop manual to determine if it is excessive or not. Anyway, having it apart as you do now would make replacing it a simple and smart task. Why not just get AC Delco OEM parts from Rock Auto?
If you drive it hard all the time with your foot in the carburator ,,,, it may be worth replacing.If you drive normal most of the time I would not worry about it.
Although I doubt it's OE, the Cam Sprocket (340235) in pic is a genuine GM piece ...
... Crank Sprocket & Chain probably are as well ... perhaps replace chain only.
Leaking seal/gasket? If damper has suffered oil over time, damper's rubber has weakened and is prone to failure.
Regardless of what others may say, I prefer a Double Roller. Then each chain is only subject to half the stress & torque put on it by the crankshaft.
Just like double & triple fan belts are better than single.
Timing Chain sets run from $19.95 to $119.95. Like Big2Bird said, something around $40+ is just about right.
Just before you remove the old set, turn the crank and align the dots to each other. Makes installing a new chain and sprockets a snap.
I also recommend a lock-down plate $5 for the cam bolts, along with a drop of LockTite Blue.
Last edited by HeadsU.P.; May 25, 2020 at 04:48 PM.
Regardless of what others may say, I prefer a Double Roller. Then each chain is only subject to half the stress & torque put on it by the crankshaft.
Just like double & triple fan belts are better than single.
Timing Chain sets run from $19.95 to $119.95. Like Big2Bird said, something around $40+ is just about right.
Just before you remove the old set, turn the crank and align the dots to each other. Makes installing a new chain and sprockets a snap.
I also recommend a lock-down plate $5 for the cam bolts, along with a drop of LockTite Blue.
But a double row chain (and triple as in HD sportster primary) Are a single discrete chain ...
... rows permanently joined together during manufacture and experience stress & torque as one discrete chain ...
... quite unlike two or more distinctly separate chains ... nor like separate fan belts on multi-groove pulleys.
Stick a 9-1100 Cloyes Street True roller in there.......one of the best bargains in the performance world. My street builds get this......the hotter stuff gets a Hex-a-Just.
That's what I have also Jebby. But was thinking it was closer to $50. ^ ^ ^ ^ ^ ^ ^ that is a good deal . . . . . .
And Jackson, no matter how you look at it, two chains welded together or not, its still twice the strength as one chain and half as likely to snap. Physics.
Last edited by HeadsU.P.; May 25, 2020 at 08:08 PM.
If I did anything it would be a double roller. Most of the issues with timing sets over the years was the plastic cam teeth what idiot thought that was a good idea ? You have an iron gear and your chain isn't awful, but while you're in there. Cloyes makes nice stuff in many price ranges.
I hear ya on the nylon teeth for anti noise / vibration. Looked good on the drawing board. But the little yellowish chunks laying in the oil pan did not look so good.
I believe some of the Ford 289s had them also? But I remember the most with Chevy 283s.
I hear ya on the nylon teeth for anti noise / vibration. Looked good on the drawing board. But the little yellowish chunks laying in the oil pan did not look so good.
I believe some of the Ford 289s had them also? But I remember the most with Chevy 283s.
70's 454 had them. I did a whole fleet of them in 73 for a pipe supply. And, pass side ( gutter side) ex manifolds. They loved to crack.
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pull down on the chain at the center of the bottom gear and the same at the top. If it moves more than half way up the tooth, replace it. If it doesnt you arent in danger of it jumping.
At this point, its obvious this is not a fresh rebuild. No need to test for slop unless its just out of curiosity.
And 90% of the work is done to swap out the set. $40? Just do it!
The gear set you have now is one of the heavy duty parts listed in the GM Power manual for use in off-road racing applications. The top gear is improved because it does not have the plastic teeth. The aftermarket chain you have might be a "little" bit worn from use but not excessive. While you have the thing apart you might just replace the chain with the proper matching GM Morse chain. The one I would look for is GM part number 14087014. Rock Auto wants about $48 bucks just for this chain but I just saw one on Ebay for $35.
Thank you All very much for the great feedback and direction!
I bought this car 2 years ago and the previous owner told to me that the engine was rebuilt but had no paperwork to prove it. From day one I could never get the engine to idle smoothly. The former owner attributed the rough idle to a performance cam. Somehow I was always a skeptic of the engine being rebuilt or having a performance cam. During some detailing work, I figured ill take a closer look. I took off that timing cover in hopes of identifying what camshaft I have. Instead I find what I believe is a loose timing chain, and NO markings on the camshaft end.
Perhaps my a rough/loopy idle is caused by a worn out timing chain? The deflection of the chain while the opposing side is tight measures 0.5" half way between 2 sprockets. Please see the attached pics. The car has 80,000 miles. Would you guys say that's the original chain and sprocket? Is 0.5" deflection considered worn out? I will definitely be replacing the sprockets and chain, just wondering, Will a fresh chain and sprockets (tighter) help improve the idle?
Timing chain?
