Starts but has issues

Tiny
CAMERONNESS86
  • MEMBER
  • 1977 CHEVROLET CHEYENNE
  • 5.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 50,000 MILES
I have the truck listed above with a 350 small block and I just cant get it to run correctly. It backfires out of the carburetor and exhaust. I've timed it to idle perfect so I shut off truck to tighten distributor and them the truck won't start back up it blows black smoke and it does when I give it barely any gas but not when I punch it.
Sunday, December 1st, 2019 AT 10:23 PM

8 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Couple questions first.

What carburetor do you have?
What ignition system do you have? Vacuum advance distributor?
What did you set the base timing to?
Have you set the total timing?

Basically we need to set the base timing and then tune the carburetor. I suspect the carburetor is your main issue. This is why it is hard starting and smoking because you have too much fuel coming in.
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Monday, December 2nd, 2019 AT 6:18 PM
Tiny
CAMERONNESS86
  • MEMBER
  • 5 POSTS
Carburetor is a 1406 Edelbrock, I believe it is just the stock AC/Delco ignition system for 350 Chevrolet small block. I set base timing to 0 degrees and it sounded great shut it off but wouldn't start back up.
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Monday, December 2nd, 2019 AT 10:14 PM
Tiny
CAMERONNESS86
  • MEMBER
  • 5 POSTS
Total timing has not been set yet.
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Monday, December 2nd, 2019 AT 10:14 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I'm Danny.

It sounds like you might have set the base timing too retarded. You should set the base timing to 8 degrees BTDC. You always want to get the most advance possible. Just adding my two cents. Hope this helps and thanks again for using 2CarPros.
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Tuesday, December 3rd, 2019 AT 2:23 PM
Tiny
CAMERONNESS86
  • MEMBER
  • 5 POSTS
Sounds good. I bought new plugs gonna try to time it in the morning.
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Tuesday, December 3rd, 2019 AT 5:55 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello again.

Okay, keep us updated. Thanks again for using 2CarPros.

Danny-
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Tuesday, December 3rd, 2019 AT 6:15 PM
Tiny
CAMERONNESS86
  • MEMBER
  • 5 POSTS
Alright, I brought my truck over to a buddies house to have it in his shop and we decided to rebuild the carburetor and it ran perfect after that. But we have run into new issues. We timed the truck and when the truck is cold it won't start unless we turn distributor. Once its warm it will fire right up and then when I drop it in to gear it bogs down and shuts off. Any ideas?
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Thursday, December 5th, 2019 AT 10:40 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
What did you set the base timing too? Try setting it to 10 degree BTDC and see how it runs. This sounds like a timing issue as I have run into a Ford 368 Y block that kicked my butt until I pumped up the timing based where I thought it should be. Basically the vehicle will tell you what it likes by running well.
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Friday, December 6th, 2019 AT 4:42 PM

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