Re-Jet with Headers?

[RickFury]

Let's assume I have stock vehicle with a stock carburetor that is properly tuned and jetted.

If I decide to install a set of headers and a dual exhaust system with a crossover pipe on a vehicle that didn't originally have these items, would I need to re-jet the carburetor?

If so, is there a "rule of thumb" on what I would need to do with the jetting to make the air/fuel mixture correct again?

[dagenham]

No. If all you are doing is exhaust you will be fine. I assume you have the Motorcraft/Holley carb. Rejetting on a stock engine will not do anything except make fuel mileage worse.

[dynodon64]

If you are running alcohol blended fuels right now with a carb, it should already have been rejetted . Alcohol blended fuel with 10% should be rejetted for 14.1:1 air fuel instead of 14.7:1. A cab won't run that lean but I'm just making a point. You need to jet richer with alcohol blended fuels.