I am restoring my 1966 F250. it has the straight 6 300 motor. I would like to go dual exhaust to add some power. any recommendations on where I should look for manifolds? I am also interested in adding some power with the carburetor. any recommendations here? 2bbl? 4bbl? anybody know which brands are better than others?


many thanks on both items.


craig.

 

Grab some snacks and drinks, sit back and start reading. What you ask has been cussed, discussed and continues to be cussed, and discussed each and every day on this Forum and here too: FORDSIX PERFORMANCE - View forum - 240-300 "Big Block" Six Performance

Read, take notes, make a plan, work the plan.

 

Offenhauser makes 4 and 2 barrel manifolds I found mine for a reasonable price and excellent condition on eBay. I have heard of 4 barrels working great but with upgraded cams and head work. Just stock a 4 can be a little too much. I run a holley 2 barrel 350 cfm and love it. I have plenty of power.

 

For the dual exhaust go with a pair of EFI exhaust manifolds. These can be found on 87-97 Fuel injected 300's ( 4.9L ) . You can also find new replacements if you don't want to deal with used ones.


For a carb swap, my recommendation is an Offenhauser C-series 4V intake manifold with a 4V to 2V adapter. If you are ok with running/rebuilding a used carb. Then an Autolite 2100 or Motorcraft 2150 2V carb in the 1.02 - 1.08 size range is a great choice and cheap choice. If you want a new carb a Holley 350 or 500 cfm 2V will also work. If you want a 4V carb then anything under 500 cfm would be a good choice. But if you are working with a budget a 600 cfm 4V will work and can usually be found much cheaper.









Offenhauser doesn't make a 2V manifold for the 240/300. They make two different 4V intakes. And a 4V carb works fine on a stock 300. They come in enough different sizes to run a 4V carb on just about anything.

 

Sorry my mistake its Aussiespeed that makes a 2 barrel manifold for the 300.

 

I haven't seen an intake from them for a 300. Their website mentions 240/300's but I couldn't find anything on their site for them. They have plenty for the small 6's and crossflow Aussie engines.

 

I agree with everything fordman75 mentioned.

 

I'd really like to go with an Off intake and 2bbl carb someday.
Right now I have a brand new single bbl Carter and she runs perfectly. My exhaust is ready for more airflow so when I do finally go with more carb, she is good to go.