Changing CAM back to stock?

Tiny
HD2424
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • 265,000 MILES
I’ve got a rebuilt engine I’m putting in the truck. I’m taking out the stage 4 cam that was in there and putting back a stock cam. I’ve got the 2 dots lined up on cam and crank sprocket also the number 1 piston it’s all the way up, so I assume I’m at top dead center. The problem I’m having is when I torque the 3 bolts for cam sprocket to 26-foot pounds according to Hanes manual then I try and turn crank it won’t turn I've even torqued it lower to 15-foot pounds and it will not turn. I hand tighten and I can spin it easy. What’s going on maybe wrong sprocket.
Monday, September 5th, 2022 AT 10:24 AM

11 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,097 POSTS
Hi,

What size engine do you have in the truck? Also, yes, it could be the sprocket is wrong. The idea that it only happens when the cam gear is tight sounds like it is touching somewhere. Have you inspected all around the rear of the cam gear? Also, is the crank sprocket fully seated? There could be a bind on the chain.

Let me know.

Joe
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Monday, September 5th, 2022 AT 8:19 PM
Tiny
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I checked that it was not binding there but I think I figured it out. The cam I put in had a slight bend to it. I took it out and put in my old cam in the new engine and it spun fine after torquing bolts.
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Tuesday, September 6th, 2022 AT 10:43 AM
Tiny
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Also, the cam I removed from the new engine was fine when I removed it. So, it’s got to be the new cam I’m installing.

It took me a while to figure it out. But a new question, what is best way to set top dead center. The heads are off.
Top dead center is on Compression stroke when piston is at top of block is that correct. I'm worried about because I took the chain off and working on it timing might be off. I can get the dots lined up on crank and cam and piston number 1 is flush with block. Is TDC on compression or exhaust?

Thanks

Please let me know what you think.
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Tuesday, September 6th, 2022 AT 10:51 AM
Tiny
JACOBANDNICKOLAS
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Hi,

Wow, I've seen them break but never bend. That certainly will cause an issue. Also, top dead center (TDC) is when cylinder 1 is at its highest point in the cylinder, just before it starts going down. At that point, both valves are closed. If you look at the camshaft, the lobes for cylinder 1 will be the furthest away from opening a valve.

I'm not certain of which engine you have, but the cam gear and crank gear should only be able to go on one way. If you have them aligned properly, you should be fine.

Let me know if that helps.

Take care,

Joe
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Tuesday, September 6th, 2022 AT 6:24 PM
Tiny
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It’s a 5.3 so you’re saying if number 1 piston is all the way up and the cam dot is at 6 o’clock and crankshaft dot is at 12 pointing to each other than that’s TDC, right?
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Tuesday, September 6th, 2022 AT 7:29 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

If cylinder 1 piston is at the top, that is top dead center. Align the timing marks at that point and you should be fine.

Let me know if you have other questions.

Take care,

Joe
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Tuesday, September 6th, 2022 AT 9:21 PM
Tiny
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Thanks for all your help.
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Wednesday, September 7th, 2022 AT 1:29 AM
Tiny
JACOBANDNICKOLAS
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Hi,

You are very welcome. If possible, let me know how things turn out for you. I'm interested in knowing.

Take care,

Joe
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Wednesday, September 7th, 2022 AT 6:41 PM
Tiny
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Sure, thing, waiting for a replacement cam. I’ll let you know.
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Wednesday, September 7th, 2022 AT 6:55 PM
Tiny
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Thanks.
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Wednesday, September 7th, 2022 AT 6:55 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

I haven't heard from you for a couple of days. I was just wondering if you have made any progress or if the parts showed up yet. I don't mean to be a pain. LOL Just interested in knowing.

Take care,

Joe
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Friday, September 9th, 2022 AT 8:01 PM

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