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Old 11-23-2018, 02:55 PM   #59
68Stepbed
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Join Date: Mar 2005
Location: 10-Uh-See
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Re: Carbed 5.3 won’t start please help!

Quote:
Originally Posted by Rdwagoner View Post
Alright gentleman, I went to crank her up today and it just turns over. I have spark, I had my neighbor hold the plug to the block and it lit him up! Lol
I’m gettibg a cam sensor fault on my MSD software while trying to crank. I got one last time but it still fired up. Not today though, will that sensor being bad not let it crank up? Any ideas?
Quote:
Originally Posted by Rdwagoner View Post
Replaced the cam sensor and the crank sensor. Fires up and runs now. I still have the check the transition slot because it seems to not want to run at all with the slots adjusted to a square. I had to open up the slots more in order to get it to run decent. I do have an aggressive cam so maybe that why?
I had a similar issue with the sensors. Here's a quick rundown of how the sensors work. The cam sensor typically only works to tell the ECM/MSD what position it's in in order to send spark to the correct side to start the engine. Once started, the ECM/MSD never reads the cam sensor again until the engine is shutoff and restarted. So, if there's a cam sensor fault, it sends spark to random cylinders until it hits one on the correct stroke. Many times, this may cause the same scenario as a distributor being installed 180 degrees out.

As for the transfer slot issue, there's a couple options. First, you need to make sure you have the correct size power valve(PV). That carb comes with a 6.5 PV. Typically, the PV number needs to be HALF of what your optimal vacuum is at idle. Which means a 6.5 PV needs at least 13" of vacuum.

Here's a good video explaining power valves.
https://www.youtube.com/watch?v=RvlmJoeIcpw

Check out this video for transfer slot and idle circuit tuning.
https://www.youtube.com/watch?v=JDPwY0LbRVY
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68 C10 stepside, LS1/700R4, TCI Engineering suspension system
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