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I bought a rebuilt 2150 off ebay for my 79 bronc with 351m & 4-speed. It did not come with an id tag bolted to it so I am having a hard time trying to find out what it came off of & tune it for my application.

Motorcraft 2150 variable venturi
1.21
tdjax - numbers printed on front foot of carb
59-main jets
75-power valve
I live 1500 ft above sea level
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1-How do I measure my float height without any special tools?
2-what is the float hight for a 2150?
3-what jet's & power vale should I install for sea level & egr delete?
4-Also there is a small vac port on the back of the carb just above the pcv port, it is in the middle of the carb body between the air horn & pcv port, where does this get hooked up at?

I have searched & been to Bubba's 351 351 v-8 workshop, but still cant figure these things out.
 

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Welcome Tenn4.:beer

Your '1.21' numbered carb is a 351 CFM, and is the most common. It might have come off of several different models and years; hard to say without the ID tag.

Your #59 jets might be a tad on the rich side. Mine came stock with #56's and I've experimented with numerous sizes, from 54 to 62, and now have #57's in mine. (351M, no EGR, and 1000' ASL). The best way to check the mixture and determine best jetting is to read the plugs, looking for a light tan color, etc....

The vacuum port you mention that's above the PCV port is for the EGR hookup.

If you're trying to eliminate pinging because of EGR disable, I've found that it's best to change the spark curve instead of rejetting. When you get it rich enough to stop pinging, you're way to rich for normal driving. You might try 'tightening' up the vacuum advance first, and see what that does. It's adjustable by using a 1/4" allen wrench in the vacuum port.

Good luck.
 

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Welcome Tenn4.:beer

Your '1.21' numbered carb is a 351 CFM, and is the most common. It might have come off of several different models and years; hard to say without the ID tag.

Your #59 jets might be a tad on the rich side. Mine came stock with #56's and I've experimented with numerous sizes, from 54 to 62, and now have #57's in mine. (351M, no EGR, and 1000' ASL). The best way to check the mixture and determine best jetting is to read the plugs, looking for a light tan color, etc....

The vacuum port you mention that's above the PCV port is for the EGR hookup.

If you're trying to eliminate pinging because of EGR disable, I've found that it's best to change the spark curve instead of rejetting. When you get it rich enough to stop pinging, you're way to rich for normal driving. You might try 'tightening' up the vacuum advance first, and see what that does. It's adjustable by using a 1/4" allen wrench in the vacuum port.

Good luck.
Thanks for the welcome ROE, glad to be here.
I have figured out the float heigt & adjustment, & now I know what that vac port on the back of the carb is. Next I checked my plugs & they are black & sooty, so I need smaller jets to lean it out? Also my egr system seems to be all there just needs to be hooked up, if I hook vacum to my egr & use it would I have to go even leaner on my main jets? One more thing what about the power valve? what size power valves should I try, if at all?
thanks
 

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There is only one power valve for the 2150 for a truck. Cars with a 2150 use a differant power valve and you should not mix the two, or so I have been told. Since you bought a generic 2150, the adjustments (choke, unloader, etc.) may not be set for your truck. I ran into the same problem when I bought a replacement carb for my truck. Thankfully, I kept the tag and was able to reset all the adjustments to what they should be when I rebuilt the carb. Ran like a champ after that with the exception of adjusting the idle needle valves.
 

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.....Next I checked my plugs & they are black & sooty, so I need smaller jets to lean it out? Also my egr system seems to be all there just needs to be hooked up, if I hook vacum to my egr & use it would I have to go even leaner on my main jets?.....
Yep, if the plugs are sooty, then you need smaller jets. I did the same thing with mine, going to larger jets to stop pinging, but then it cruised too rich. What I did was go up 1 jet size, and then adjust the timing curve to eliminate the pinging. I did that by setting initial timing at the stock 6*, and installing weaker distributor springs to get more timing in at lower RPM. Then I fine-tuned it by adjusting the vacuum advance. Crane makes a good kit for experimenting with different dist springs and advance weights.

As far as EGR goes, it simply replaces some of the air/fuel mixture with inert exhaust gases to cool combustion, therefore it dosen't affect the fuel mixture. When you delete EGR, then the combustion is hotter, and bigger jets will cool it down and prevent pinging......but then it runs too rich. If you want to reconnect the EGR, I'd put smaller jets in it (closer to stock), and if you have any pinging, tune it out by adjusting the timing curve......
All of this while reading the plugs.
Ain't these old trucks fun.....?
 

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There is only one power valve for the 2150 for a truck. Cars with a 2150 use a differant power valve and you should not mix the two, or so I have been told. Since you bought a generic 2150, the adjustments (choke, unloader, etc.) may not be set for your truck. I ran into the same problem when I bought a replacement carb for my truck. Thankfully, I kept the tag and was able to reset all the adjustments to what they should be when I rebuilt the carb. Ran like a champ after that with the exception of adjusting the idle needle valves.
The holley power valves work in place of the chitty motorcraft ones (the jets will not interchange, though). You need to know your vacuum readings at idle, light cruise and acceleration to be able to pic the correct power opening point. The power valves openings range from 10.5 to 2.5 of vacuum.

As an example: my bronco has 20"Hg (vacuum) at idle and cruises around 12"Hg or so and then drops down to @ 6-8"Hg while under normal acceleration. This tells me that I want a power valve that would open around 8-9"Hg to allow the extra fuel I need. You don't want one opening too early then you could get a bog/hesitation from running too rich, and visa versa, don't want one opening late and not having the extra fuel which could lead to engine failure.

Some say a rule of thumb is to take half of your vacuum at idle to find the correct power valve you need.

If you have 10"Hg at idle then start with a 5.5 or 4.5 power valve and test from there. Your engine will let you know.
The jets can be hard to find, but have been know to fill the jets with jb weld and redrill them to the smaller size that I needed if that is the case.

I know the 1.08 (capri V6) series came with 0.050" jets (or smaller) in it and was rated at about 280cfm and the 1.14 (260 & 289 V8s) series came with 0.052" - 0.054" jets and was rated at 300 cfm.

Kirk
 
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