Amateur carb question

[berickso]

I have read as many of the carb threads as I can find, and I now know better than to ask what the best kind of carb to run is, but I still have a question.

Running a 302 in my 74 from (what I believe) is an early production 81 F-150. Currently have a UREMCO remanned 2150 on there (that is spec'ed for an 80 302, but not an 81), and I think I need a new/remanned carb. I imagine that I want to put a 1980/81 carb on there, NOT a 74 Bronco 2100/2150, correct? Would it be possible to put the older model carb on there, or am I asking for trouble?

Thanks for any feedback you can give, so grateful for this forum.

 

[Rustytruck]

trouble or not who knows all these carbs were tuned to the truck for emissions every year they were different and in many different states they were different too especially California and their egr/smog pump engines 1974 Broncos were not mandated for unleaded gas catalytic converters just cars in 75 and later they had to deal with unleaded gas. for a generalization the later cars were specified to run on much leaner settings. if sticking with the early carb the main jet sizes tend to run jets sizes from 46 to 52 for the 289/302 depending on the altitude. smaller for high altitude larger for low altitude so be aware of that. its all a crap shoot with emissions and the changes to our modern day fuels. and what emission parts you carry forward in your adventure.

 

[berickso]

That helps, thanks--I have taken out most of the emissions equipment from the 74, so I might try going with the earlier carb. So many of the parts are interchangeable from the various years of the 302 block, but I get nervous when they aren't the same...

 

[B RON CO]

Hi, what is your Bronco doing that makes you think the carb is bad?
If there is a problem with the carb most guys can successfully rebuild an old carb. The rebuild kits come with all the parts and come with good instructions and diagrams. Care, attention to the details, getting everything spotless clean, and rebuilding a carb is a rewarding experience.
Good luck

 

[m_m70]

Care, attention to the details, getting everything spotless clean, and rebuilding a carb is a rewarding experience.

agreed!

 

[armynavy17]

If you're considering rebuilding it yourself, I've had great luck with the kits and parts from Mike's Carb Parts.
https://www.carburetor-parts.com/

 

[bmc69]

The engine may actually run better with one of the earlier model carbs. But at the end of the day, all carbs are stupid-simple air-fuel mixing devices, so getting any of them to work properly is easy stuff.

 

[armynavy17]

Forgot to mention that only a true old school carb shop has even the slightest chance of actually supplying the correct carb for the engine. As Rustytruck said, each carb was built for the specific engine each year.
A parts store will tell you the carb is for such and such year and model, but it's also for every other vehicle that ever came with that model carb. The reman companies certainly don't care what parts go into the core, they just go to the parts bin for a 2100 carb and take whatever they need.
If you're set on replacement, I'd look on eBay for an original carb of the correct application 2100/2150 and rebuild it when you get it. The application details can be found on Mike's website.

 

[bmc69]

Forgot to mention that only a true old school carb shop

I owned a well-regarded carb shop back in the 1980s when I was also an automotive machinist. In addition to standard rebuilds, I built a number of custom carbs for dirt track racers. It was a good "side business" then ....I would starve to death nowadays. LOL.

 

[berickso]

I am having some flooding issues--I think. It shuts off randomly and then often won't start back up. I have replaced all the spark equipment, from distributor to plugs to timing chain to module, adjusted timing, etc. I have checked vacuum and I've got good vacuum (~18), played with the idle adjustment screws, but it doesn't want to run smoothly unless the idle is set really high. It ends up too rich, and then is flooding. I have replaced some parts of the carb, but am at the point where if swapping out the model to something simpler would help at all, it feels like a good investment. If this one was the original for the engine, I would rebuild, but it's clearly a reman.

 

[m_m70]

So has this carb ever run right for you??

I think. It shuts off randomly and then often won't start back up.

Vapor lock maybe??

but it's clearly a reman.

pretty sure that's all you'll find. Is your intake from '74??

 

[berickso]

I believe the intake is from the 81. I have been thinking about vapor lock, too. I tried starting with the cap off the tank, and I have insulated all the fuel lines. It's doing it even when it's cold, which makes me think it's more carb and less vapor lock, but I'm not sure. The carb did run right at one point, but then it sat for awhile. Ran fine again for a bit but with regular driving things have gotten progressively worse.

 

[m_m70]

how's the fuel pressure?? Fuel filters been changed recently??
I run a fuel pressure gauge between the pump and carb to help diagnose any problems I have with my carbs.
just a thought........

 

[Rustytruck]

check your fuel lines from front fuel pump to rear make sure hoses are good and clamps are tight you don't want them sucking air if you still have the metal fuel under the drivers seat you can replace the o-ring under the switch cap if need be. You will also need to replace the gaskets under the carb and spacer if your truck has one. under the carb use an isolating gasket its almost 1/4" thick and has plastic support rings around the stud holes. may need longer carb studs.