Hey guys, my carburetor on my 78 400 was jetted for 3000 feet but when I moved to Green River, WY, elev 6300 feet, it started to run quite a bit rich. Go figure. Anyways, if any of you guys have some 50-52 and maybe even some 54's I would really appreciate it. I have tried all the parts stores and Ford just laughs at me. I have found a lot of old Motorcraft 2-bbls but they all seem to be about 57, which is what I am running now. There is no question, though, I am running awfully rich. We could probably just mail them so get in touch of you've got em. Thanx a ton. Oh yeah, I also posted this in the carburetion forum so I apologize for the redundancy.

 

Doesn't that carb take Holley jets? I can't remember.

Bear Tracks

 

jdawg78,

I don't think #57 jets should be a problem at 6300 feet altitude. I'm at 5400 feet and running #63 jets that are just slightly too rich.

Before you change the main jets, consider a couple other possibilities.

Have you checked the choke? If it stays closed too long, or tries to close at warm temperatures, it will cause over-rich problems. Did you move the choke rod to the "ALT" hole on the choke plate lever? That keeps the choke a little farther open for high altitude.

A more likely culprit is the power valve. Many late '70s truck calibrations specified a power valve that opens at fairly high vacuum (10-12 in/Hg). Since you moved to a location at higher altitude than you were before, your engine is producing less manifold vacuum, perhaps not even enough to close the power valve when the throttle opens. I've seen that many times in 2150s that weren't calibrated for high altitude.

I suggest you change the power valve first and try it. At your altitude, I'd recommend a power valve that opens at 4-6 in/Hg maximum. After you do that, you may find you're running lean and need to increase the main jet size.

You can get Motorcraft 2150 power valves at any Ford dealer and at most chain auto parts stores. Here's a page with power valve specs and part numbers:

http://home.earthlink.net/~bubbaf250/2150carb/carb10.html

The Motorcraft 2150 doesn't use Holley jets. If you need jets for the 2150, here are a couple of places you can get them:

Parker Carburetion http://www.Holleypartsforsale.com

Carbs Unlimited http://www.carbs.net

 

I'll check when I get home. I live in Denver. You might also call Vern's Carb Shop 303-985-7525. They had the size I needed. I know he works with people all over the contry.

 

You can also increase your timming by about 1 degree per 1,000' of altitude.

 

Sorry I couldn't find any. I probably put them in a safe place. If I find them this weekend I'll let you know.