Timing Chain Help (first timer)
Thread Starter
Race Director
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From: CO
Timing Chain Help (first timer)
My vette manual shows TDC on a SBC when the timing mark on the crank sprocket is at 12 o clock and the camshaft is at 6 o clock.
I thought I had lined them up and I took off the cam sprocket and upon closer inspection I think I used the wrong mark. I think I took off the chain with both marks at 12 o clock.
The peg on the cam is at the 9 o clock position. I remember how it looked when I took it off so If I need to put it back together and turn it more I believe I can. But I dont really think it matters as long as the new one goes on the same way will it? i.e both marks at 12 o clock.
I thought I had lined them up and I took off the cam sprocket and upon closer inspection I think I used the wrong mark. I think I took off the chain with both marks at 12 o clock.
The peg on the cam is at the 9 o clock position. I remember how it looked when I took it off so If I need to put it back together and turn it more I believe I can. But I dont really think it matters as long as the new one goes on the same way will it? i.e both marks at 12 o clock.
Burning Brakes
Joined: Aug 2004
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From: roanoke va
with the marks as you described it is tdc on #6 if you turn the crank 360 degrees you have it at tdc #1. the cam only turns 1/2 turn to every turn of the crank. just line it up with crank timing mark at twelve and camshaft timing mark at six and you will be fine. dont forget to turn crank 360 degrees and install dist. for #1 cly.
Thread Starter
Race Director
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From: CO
So does it have to be at TDC #1 to put a timing chain on? Or can I do it with it at TDC on #6? I am just going to put the chain on the exact same way it came off.
I dont think it will matter , but I could be wrong. The distibutor is not coming out.
I dont think it will matter , but I could be wrong. The distibutor is not coming out.
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
You can install the gears with the dots either pointing together (crank at 12 o'clock and cam at 6 o'clock) or with both dots pointing straight up. It doesn't matter, since the cam rotates at 1/2 crank speed - either way will install the cam in the correct position relative to the crank.
However, for distributor installation, you have to be at the #1 firing position (TDC on compresion stroke). TDC compression stroke is with both dots pointing straight up. When the dots point together, you are at TDC on the exhaust stroke. Common mistake people make is to install the distributor in this position.
If you have not pulled the distributor out, it is still correctly clocked to the cam. So in yuour case, you can install the dots either way, and the distributor will remain correctly clocked to the event cycle (exhaust versus compression stroke).
However, for distributor installation, you have to be at the #1 firing position (TDC on compresion stroke). TDC compression stroke is with both dots pointing straight up. When the dots point together, you are at TDC on the exhaust stroke. Common mistake people make is to install the distributor in this position.
If you have not pulled the distributor out, it is still correctly clocked to the cam. So in yuour case, you can install the dots either way, and the distributor will remain correctly clocked to the event cycle (exhaust versus compression stroke).
Thread Starter
Race Director
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From: CO
Thanks for the replies guys! I was pretty sure that it wouldn't matter for a chain replacement, but I wanted to check with the forum first.
Now to get a sprocket puller and a chain, then on to my front suspension rebuild.
My goal is to get out to second creek (track) before they close. This is the last year I may be able to open the vette up legally on a road course!
Now to get a sprocket puller and a chain, then on to my front suspension rebuild.
My goal is to get out to second creek (track) before they close. This is the last year I may be able to open the vette up legally on a road course!
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
You don't need a sprocket puller. Just take a sharp chissel, stick it between the teeth of the crank gear right where the keyway groove is located, and give it a few whacks. The gear will crack at the keyway groove and slide right off the crank.
And, no - you won't hurt the crank doing this, in spite of what some may say. Every crank grinder in town removes their gears this way, and I've been doing it like this for almost 30 years with no trouble.
And, no - you won't hurt the crank doing this, in spite of what some may say. Every crank grinder in town removes their gears this way, and I've been doing it like this for almost 30 years with no trouble.
Thread Starter
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From: CO
Hmmmmmm ok. 1 BFH on the way.
I had just assumed that I needed a puller. I will try this method and see how it goes. If the advice came from anyone else I might second guess it.
And seeings how this is the first time I have done this, How about re-assembly? Do I need anyting special to put a new one on?
I had just assumed that I needed a puller. I will try this method and see how it goes. If the advice came from anyone else I might second guess it.
And seeings how this is the first time I have done this, How about re-assembly? Do I need anyting special to put a new one on?
Tech Contributor
Joined: Aug 1999
Posts: 14,356
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From: At my Bar drinking and wrenching in Lafayette Colorado
You can tap the new one on with a drift punch. If you'd like, I can swing by your place with my special chissel, drift punch and special BFH and do a demo for you: it takes about 4 minutes to crack the old one off and re-install the new one.
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Thread Starter
Race Director
Joined: Dec 2000
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From: CO
Let me see what I can do first. I will let you know though, maybe you can help me drop the suspension arms and get the coils out "while we're at it" 
I haven't ever done that either and its the only thing I have fear of getting killed doing 
I haven't ever done that either and its the only thing I have fear of getting killed doing
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,332
From: At my Bar drinking and wrenching in Lafayette Colorado
Piece of cake. Drop me an e-mail at home if you need assistance over the weekend:
V8FastCars@msn.com
V8FastCars@msn.com
Thread Starter
Race Director
Joined: Dec 2000
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From: CO
Just an update. I was able to use the hammer and chisel method and the gear split in two. Pretty easy.
For the reinstall I just put the new gear in the oven at 400 for about 30 minutes. Then it slipped on , with a little tap from a hammer. Went right on.
I appreciate all the help. Breaking of the gear was ALOT easier than I thought it would be.
For the reinstall I just put the new gear in the oven at 400 for about 30 minutes. Then it slipped on , with a little tap from a hammer. Went right on.
I appreciate all the help. Breaking of the gear was ALOT easier than I thought it would be.
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,332
From: At my Bar drinking and wrenching in Lafayette Colorado
The technique works every time, and it's a lot easier and quicker than standing on your head with a gear puller to take it off in one piece. Since the gear is hardened, it's very brittle: a few hits with a hammer and a sharp chissel right at the keyway will crack or break the gear every time. Glad it worked well for you!
