Crankshaft gear position

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Nov 6, 2013 | 04:40 PM

75sl48

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Crankshaft gear position

So I'm finishing my hci swap, finally, on my 75. One of the things I replaced was the timing set. I ordered the comp cam magnum set. After looking at and trying to install it I realized that the crank gear was machined wrong. The key slots are the shape of the corresponding mark. Meaning the square is square and circle is circle. Get the drift. Lol. So the only position it fits is 4* retarded. My question is does it really matter? I mean as long as #1 is at tdc and I line up the cam up with it it won't really be retarded, right?
I have emailed comp cams and they admitted that the piece was obviously machined incorrectly but have not come up with a solution for it.

Nov 6, 2013 | 04:55 PM

Scottd

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From: Syracuse NY

[QUOTE
I have emailed comp cams and they admitted that the piece was obviously machined incorrectly but have not come up with a solution for it.[/QUOTE]

The solution is they send you a part thats machined correctly. You dont want to do this job a second time. Will 4 degrees matter? Depends on who you ask, but Id hate to spend the rest of my time second guessing myself. Why cant you just get the correctly manufactured part?

Nov 6, 2013 | 05:00 PM

75sl48

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That's what I'm hoping to do is get the correct set in return since they did it incorrectly.

Nov 6, 2013 | 09:27 PM

Super6

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Have you tried taking the gear to a machine shop to see if they can broach a square keyway where you need it?

Nov 6, 2013 | 09:42 PM

TimAT

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Many cams are built with 4* advance built in. Check with your cam company to find out if yours is. If so, I read your description with the crank gear installed 4* retarded then your install will put the cam at 0*. 4*advanced (cam) +4* retarded (gear) =0*. Short of doing the full degree the cam installation, you can't really know where it will be.

Nov 6, 2013 | 10:04 PM

68post

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From: Indianapolis IN

Yes you should degree the cam, if the cam does end up being 4* retarded it may make a huge difference, (it could be more than just 4* retarded also).
I'd send their junk back and buy a brand name set that is known for their timing sets.

Nov 7, 2013 | 12:14 AM

iokepakai

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From: Kona Hawaii

Degree in your cam,it's not that difficult.Check you tube for tips.For better low end response advance your cam 4-8 deg.If you want more high end retard the cam.As stated your cam could already be advanced but you can't be sure until you degree it.What happens when you advance the cam you close the intake valve sooner which builds more cyl pressure for increased lower end torque.This is the multi key timing set I used....http://www.jegs.com/i/JEGS-Performan...oductId=761240
My roller cam install..http://forums.corvetteforum.com/c3-t...-cam-swap.html

Nov 7, 2013 | 06:14 PM

75sl48

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I ended up mocking it up and decided to just take a file and take some off the gear and crank itself and it slid right on. My cam card says to install straight up. I know I should degree the cam and I might. I know I have to in order to get every bit of performance out of it. Is it hard to do with the engine in the car?