Hi, how much does this help over the stock 1BBL and single outlet exhaust on the 300? Im looking to put the 390 Holly 4BBL, Offenhauser 4BBL intake, and the EFI exhaust manifolds on my 1982's 300. Anyone else have this combo? How do you like it? Thanks Fred

 

Mucho! (see sig - below)

broncr

 

That's a good setup, but if you're insistant on running the 4BBL, run an Offenhauser "DP" manifold. The "C" series manifold they sell in the JCW catalog is an open plenum, and kinda sucks for low-to mid- range power with a 4BBL. I am running a "C" series, EFI duals, and an old Motorcraft 2150 2BBL, of 354cfm. More than enough to turn 5,500rpm, and very streetable too. When you do this though, upgrade the ignition to use every bit of power. I have a Performance Distributors DUI unit, and it is awesome. It's custom built for the truck. It also cost nearly $400, but was worth every penny.

 

I will let you know how the conversion works in about a week! I am doing the conversion as we type (more or less). I am Using a Holley 390cfm, Offy "C", EFI exhaust, Walker converter pipe, Walker Cat, Flowmaster 40 and Lokar SS throttle cable. Also adding an Nordskog air/fuel bar graph meter.

 

I've got the Clifford single plane - which is an open plenum like the Offy "C". I got it for fifty bucks. If I could find a DP cheap, I might switch, but I can't complain about poor low-mid range power with my SP (single plane) - SOP boost throughout the driving range!

Look over your Walker - mine was OK, but I've read complaints about poor workmanship. Check to see that the "Y" connection is fully open. & I had to use some muffler goop to get a tight seal at the flanges.

broncr