What do I tell the counter dumby at the local auto parts store that I am looking for main jets for my Motorcraft 2150? Is there a specific part number or name I need to use?

Will Holley jets fit the Motorcraft?

Thanks.

 

holley jets are NOT the same as the motorcraft ones.

i got jets here: http://www.carbsunlimited.com/ford2v.htm

btw: my mildly built 400 currently runs kinda lean on #60 jets.
thinking of trying 63's. what are you running/going to?

cheers!

 

Well, I'm not sure what I am running...yet. I just know that changing the jet sizes were my next step for my rebuild.

I'm running a 351M. Hopefully, by next fall I'll stroke it to 400. But before then, I just wanted to tune it as much as possible.

Thanks.

 

Redone, I'd guess that you're running #57's, if it's a factory carb. That's what was in my 78 Bronco. I switched mine to 60's to cure pinging, and now it's slightly on the rich side according to the plug color. I'm thinking of going back down a size or two. It seems that a little jet size change will go a long way, at least on my (stock) 351M.

 

The effect of changing jet sizes depends on your altitude and on the sizes you are changing. Other factors being equal, changing from 60 to 62 will have more effect on A/F ratio than changing from 50 to 52. And changing from 60 to 62 at 200 feet above sea level will have less effect on A/F ratio than changing from 60 to 62 at 5000 feet above sea level.

The optimum jet size depends a lot on altitude. The size that works best on your engine at 5000 feet above sea level is not the same size that works best on your engine at 200 feet above sea level.

The optimum jet size also depends on volumetric efficiency, which varies with the components (especially the camshaft), and even over time as an engine wears out. So the size that works best on your engine at 5000 feet above sea level might not be the same size that works best on my engine at 5000 feet above sea level.

Unless you have access to an exhaust gas analyzer (measures CO, CO2, and HC at least), tuning the carb jet size is a lengthy trial-and-error process. You just have to keep making incremental changes and measuring the results until you zero in on the right size.

 

it would aslo be a good idea to smooth out the air horn casting marks to improve flow. each carb will vary but it takes less than an hour with the right tools and know how. a very fine grit wheel in a dremel works well.

 

Cool.

Thanks for all the advice guys.

Now, if would just get a little warmer outside.