Fuel System: edelbrock 1403

[bhapner]

I just bought an Edelbrock 1403 carb for my 289. I have a 4bbl manifold I am going to modify. It appears I can grind the manifold to match the carb. Do I need to remove the material between the primaries and secondaries? Or should I leave it in. (I have pictures of a modified manifold with that material removed, and wondered why it was done and is it necessary?)

Input appreciated!!!

hapner

[thunderations]

You can do it either way. Removing the extra material is cosmetic.

[karterfred88]

I just bought an Edelbrock 1403 carb for my 289. I have a 4bbl manifold I am going to modify. It appears I can grind the manifold to match the carb. Do I need to remove the material between the primaries and secondaries? Or should I leave it in. (I have pictures of a modified manifold with that material removed, and wondered why it was done and is it necessary?)

Input appreciated!!!

hapner

The ones with "slots" instead of individual holes are usually converted 2 barrel manifolds, if you have an older 4 barrel manifold you could do either, but if hand cutting out the holes it's easier to use what you have and enlarge as necessary. Make sure your studs will be in the right place, use a new base gasket as a template and go to it.

[Mike Van Veghten]

As noted, you can do it either way...but it is NOT cosmetic..!
Any time you increase the plenum volume, you increase the higher rpm power, while lessening the low rpm power. While it may not be by much, that is...what happens.
You can actually remove the entire center of the plenum area if you like, but as noted, it may add too much plenum and take away too much low rpm power for around town driving.
If it were me, I'd make two long slots (front to back). Also, after you are happy with your carving, make sure you round all sharp edges left inside the plenum. A nice large, 1/4" to 3/8" radius anyplace the fuel and air have to go around a corner.

You did make a good choice on the CFM size...

Mike

P.s. - A small 5/16" x 5/16" (3/8" x 3/8" will work) or so slot cut into the plenum divider, will help with smoothing the idle, and make the initial tip-in of the throttle smoother.

[bhapner]

Thanks all for the input. I'll just leave the dividers in place. I'm not going to race so I'm not too interested in top end.

[56GH]

It may not be relevant since you're starting with a 4-barrel intake, but there's some good information in the following articles: see the TW Studebaker Co-operator for December 2000 and Jim Pepper's answer about modifying the intake manifold from 2 to 4-barrel. There was also another article that was more complete and gave explicit maching directions in another TW but I couldn't locate it off-hand. Also see the June 2004 TW for a good article about adapting Edelbrocks to 289s by Brian Curtis and Art Unger.