I've been told that before I put my intake manifold on I should grind down some of the dividing rib below the carb. Attached a generic picture showing what I'm talking about. Has anyone else done this or heard if it's good or bad? I would figure if it did anything to improve performance Edelbrock would have made it that way?

Olds 350 with stock Rochester Quadrajet.

Any input would be appreciated before I start grinding

 

I have seen that done before but have no idea what it does.

 

What it does is equalize the area beneath the carb so the carb is feeding all of the runners from both sides of the carb. There are different theories about performance help. Helps in some cases, not in others.

 

Normally worth about 7-10 hp above peak. Do it but round the edges.

 

about 3/8" of an inch down sound about right, or, should I go deeper?
And round over the top edge.

Thanks, it's on the "get it done this weekend" list.

I'll post some before and after pics.

 

Well it's finished. Figured I post some pictures. It turned out pretty good, didn't hit the carb mounting surface and screw it up. That was my major concern.

Taped off so that I wouldn't hit the edges. Came close a few times so I added some carboard.
TAPED OFF TO KEEP FROM HITTING CARB BASE.JPG

This was the target depth for grinding
TARGET DEPTH.JPG

Grinding in process
GRINDING IN PROCESS.JPG


The finished product. Since I had the Dremell out to round off the center rib I figured I would hit the Edelbrock and Oldsmobile Performer 350 text and take the paint off so it would stand out a bit. I think it looks pretty good if I do say so myself.....
FINISHED.JPG

While taking the photos I noticed these two holes in the bottom. Since I bought this at a flea market I have no idea if they are supposed to be there or if someone drilled them. Anyone know if they were put there by Edelbrock???
ARE THESE HOLES SUPPOSED TO BE HERE.JPG

 

EGR passage

 

NICE job i like the edelbrock clean up too.

 

Destructor,

Do the EGR passages get pluged or are they fine the way they are?

 

The holes stay...at least on mine they did! By the way, let us know if you've noticable difference! That is, if you had it on already and had a baseline to compare to!

 

You could have gone a little deeper especially if you're not using a spacer plate but it looks nice nonetheless.

 

No baseline, going from a bone stock 350 4bbl with 130K and a weak #8 cylinder to:

Machined 7A heads and block, heads pocket ported valves done

Block .030 over, new forged pistons, speed pro L2321F with 6cc dishes (should be better compression about 9.6:1) they were kinda hard to find.

Comp Cams XE 268H-10 http://www.compcams.com/Cam_Specs/Ca...csid=1171&sb=2
Lifters
new springs and retainers
Double roller timing chain

Comp Cams 1441-KIT Magnum roller tip rockers
push rods
guide plates

Flow tech 31150FLT headers (after looking them up the web site it says "
"WILL NOT FIT COLUMN MOUNTED STANDARD OR FLOOR MOUNTED AUTOMATIC TRANSMISSIONS"
Crap, we'll see about that....)

The Edelbrock manifold in the pictures

Rebuilt quadrajet for engine specs

Everything else in or on the engine is new.

Hope this combination yields a decent, fun daily driver motor.

 

Cutlassefi.... is it really worth it in your opinion to do this on a big block performer intake. What change if any are you likely to see???

 

Word is it can't hurt, had everything torn down so I figured I would do it while I could. Can't imagine it would have a negative effect and it only took about 30 minutes or so. We'll see what happens I guess. I'll never know if it made any difference because I never ran it with the center rib the way it was..... Ironic that someone would spend the time doing something based solely on others advice....

 

Yes
The guys at Wilson manifolds in Ft Lauderdale swear by this. They did it to my EFI'd Performer RPM. They claim 7-10 hp gain above peak with little or no loss below it. In a big block that's even better, especially since the BB Performer doesn't have a bunch of plenum area to feed all the cubes anyway, part of the reason why they don't run well higher up.

I know this, it make sense, and on mine I have 2 O2's, 1 in each collector. My air/fuel ratios don't vary more than .2 side to side anywhere in the rpm range. I'd like to think the manifold has something to do with that.

 

Cool. Thanks very much.

 

You're welcome.

 

Good job! It looks like it turned out great.