Need help, 67 Camaro with rhs 502
 

When I go to start it, the starter seems to engage the flywheel and spin the motor a little and then a loud bang and it seems like the motor kicks back the opposite way.
Sometimes it will turn and fire up, but seems like it runs a little rough.

Here is a video I made of it. The first two starts are with the coil harness plugs disconnected and it spins the motor fine like that. The others are with them connected and you can see how the motor seems to kick back https://m.youtube.com/watch?v=gmSln5mdTEc

Too much crank timing advance is my guess.

Might be useful to tell folks what EFI controller etc you are running.

Don

Thanks for the reply, okay so it has a pcm out of a 2004 gto and a vaporworx fuel controller, and the pcm has a base tune in it.

What cam? Base tune from a 2004 GTO?

Don

It’s a cam motion hydraulic. I had a base tune done for the 502 motor

I’m no expert but I think the timing is too advanced when cranking. I would get a better tune. Maybe one of the experts will chime in.

Don

I completely agree here. You need to get HP tuners/EFI Live scan of your cranking ignition timing, before you try to start the car again. It will likely break the starter boss off the block, if you continue. If it were an Oem block, it already would have broke. Check the timing first. I’ve seen this many many times.

I watched the video.
My guess is you have too much ignition timing advance during cranking.
Please please put a timing light on and check during cranking.
My guess on your application is you want about 15-18 degrees btdc while cranking. That means you want 15-18 degrees between 0-400rpm.

I have a F.A.S.T. fuel injected 572ci 68 Camaro.
I completely shredded my flywheel when it backfired through the intake when I had cranking timing set at 22 degrees btdc.

Please don't do what I did! Ugh.....,

Keep us posted. You have friends you've never met who care!

Thank you for all the help, I will definitely check crank timing this week.
I will let you guys know what I find with that
Thanks again

sic7camaro,

I apologize for an error..,
When I shredded my flexplate, the crank timing was 28btdc, not 22btdc like I posted earlier.

Sorry.

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

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

https://www.karlkustoms.com/Resource...12576407_g.jpg

4x There's also an LS3 4x with single bolt
https://i.ebayimg.com/images/g/xYwAA...2k-/s-l640.jpg



https://sites.google.com/site/sloppy...lector-id-page