Need help, 67 Camaro with rhs 502

[sic7camaro]

Checked the crank timing and it’s at 13 degrees so I’m really lost as to what’s causing this problem.
I forgot to mention before that it doesn’t do it every time either, sometimes it fires right up.
If anybody has any other ideas as for what’s causing this, I would really appreciate the help because I am at a lose with this thing

[David Pozzi]

Make sure your cam sprocket has the correct number of triggers. A 2005 GTO will have a 1X cam and 24X crank trigger with black crank sensor but later (2006) cam sprockets are 4X that go with a 58 tooth grey crank trigger sensor. I drove a car that had a 4X cam sprocket, 24 tooth crank trigger, but the ECM was for a 1X 24 tooth GTO and set up for 1X programming. It would either start fine, or buck the starter depending on which lobes it sensed first on startup.
The LS2 came in both flavors depending on year. Some time in 2006 year of engine manufacture, the changeover to 4x/58 took place.
1X

[David Pozzi]

4x There's also an LS3 4x with single bolt




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