Back fire through carb

1991 CHEVROLET TRUCK
160,000 MILES • V8 • 4WD • AUTOMATIC
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KARLAREIMJR
  • MEMBER
  • 1 POST
k 1500, I changed the heads (due to a cracked head) while i had it apart i changed the timing chain and gears. I re-assembled the engine and i now have a slight hesitation and it backfires through the throttle body. So I changed distributer, rotor cap plugs wires. everything was assembled properly (firing order) still hesitates and backfires through the throttle body i was advised to check all vacuum hoses (all good)
then i changed the map sensor, knock sensor, coolant temp sensor, and all vacuum hoses and still responds the same. the only engine code is 44. which is to lean, would this cause the truck to backfire if not what am i missing?
Jan 14, 2008 at 8:38 PM
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KASEKENNY
  • CAR REPAIR CONTRIBUTOR
  • 18,907 POSTS
More than likely, we have a timing issue. Take a look at this guide which will cover the most common items but based on what was done, I would jump to the timing:

https://youtu.be/HiI_eeFg-2A

https://www.2carpros.com/articles/engine-backfires-while-running

Below I am attaching the timing info and I would set number 1 cylinder to TDC and then check the timing and make sure the engine is set on the proper mark.

If not, then we need to remove the front cover and see if the timing marks are lined up.

Please run through this info and let us know what you find.

Thanks
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Feb 14, 2022 at 6:03 PM
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