Q: Carb swap kills motor

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Hi, I need some help. I have a 1973 350 Chevy motor which had an old Edelbrock 4 barrel carb. that hesitated and backfired a lot. I found a rebuilt 1973 Rodchester Quadra-jet for a good price, so I swapped out carbs. The Q-jet starts her and idles her smooth and strong, but the second I try to put it into gear she kills, even when allowed to fully warm up. The other carb. would let it run in gear once warm. Plus, I get a double whammy when she dies hot. Hedder heat retards my starter even with a shield wrap. Then it won’t start until she’s cool again. There’s no idiot lights and I can’t scan for check engine codes because this motor was dropped into a 1982 El Camino and I don’t think any of that was set up. Any suggestions to make run in gear would be greatly appreciated. She’s what gets me to work and back daily-(was). Thanks in advance, Tom

Hi Tom:

It’s very difficult to give you a "guess" as it’s always best to inspect the entire set up including your intake manifold, vacuum lines and your emissions hardware, but sometimes when you swap from an Edelbrock 4 barrel carb to a Quadra-jet, you’ll also have to complete some wholesale jetting changes, make sure all vacuum lines are connected correctly and even sometimes change your intake manifold. If I were in your shoes, I’d start by checking all vacuum lines to ensure there isn’t a vacuum leak. I wish we could be more help, but we would need to be there to get a big picture point of view to determine the best course of action.

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