Ok, I'm stumped. I've been told several different stories about rejetting the carb on my 86 F150. 4.9. A few have told me that Ford leans them out and you can't put smaller jets in, Others have told me that you can rejet the Carb. Whos right?

 

Do you still have the feedback carb and EEC in place?

 

yes, and no vacuum leaks too. Emissions testing here is strict, and they do a thorough inspection.

 

I've got to think changing the jetting would cause the EEC to freak out. I've you've got to deal wit strict emissions testing you should leave it as it came from the factory.

 

Well I was thinking about changing to a smaller jet (maybe the next size down).

 

billt28,

If you are good with carbs you can clean up the carb throat by removing any cast parting lines and polishing the throat. This will improve the air flow by reducing air turbulance. My experience shows that this increases power and MPGs. However the increases are small (but noticeable) my wife even noticed the ole Plymouth seemed more peppy.

 

Why do you want to lean out the carb?

Ford spent a lot of time and money tuning for the best economy/emissions. On an otherwise stock vehicle there's not much to be gained by changing the factory settings.

 

"Well I was thinking about changing to a smaller jet (maybe the next size down."

Same question as BVA X2. For what purpose?

 

Because the truck won't pass emissions. Everything is new. The carb was rebuilt in FL, then shipped here.

 

What's the issue with passing emissions? What are your output numbers?

 

Sorry its taken so long to get back. Its not passing on CO. It measures 3.28. Max allowable is1.86.

 

Recarbco - Carburetor Smog Diagnostic Chart

Check that link, lots of good info.