My car is as my screen name implies, a Big Block 69. At one time my car had a factory aluminum intake, 3885069. The intake was not original to the car. It was a dual plane with a divider. The car ran great with that intake. I had no reason in the world to take it off, except I also had a Holley Strip Dominator that I really wanted to try. The Strip Dominator killed the low end torque. The car doesn't really wake up until about 4000 rpm but I don't drive it that way often enough to enjoy it. It has 488 gears so it gets right up there pretty quickly, but it really isn't that much fun to drive the way it is now. Common sense says to just put the other intake back on, but I sold it. (I really need to stop selling stuff) Anyway I have a pretty close copy of the 069 intake. It is a Weiand aluminum dual plane with a divider. But before I swap intakes I thought I would ask here if anyone had ever tried to put a divider in a single plane intake like the Holley Strip Dominator. And what were the results? It should be easy enough to do with sheetmetal. Has anyone ever tried this or heard of it being done?
Thank You for any help you may offer,
Rick
Big Block 69

 

Not sure what sticking in a divider on a single plane would do, it still will not have the characteristics of a dual plane.
A modification to the dual plane is to slightly lower the divider, 1/4". See the link below.
Intakes such as the Edelbrock RPM series dual plane already have the divider notched.

 

Agree, go get yourself a good dual plane todays designs are pretty decent
Weiand and Dart have some nice ones
one thing to love about big blocks is you can have the cammed up power, pull some gear out of it and have your cake/eat it too.

 

I switched from the torker to the RPM air gap and there was a world of difference in the bottom end. although I have a sb350, a dual plane proved better for low end.

 

I'm not sure that's a great combination with that gear.I've taken the entire divider out of a dual plane and picked up hi end power with some loss on the low end power which worked out because it didn't blow the tires off as bad but really wasn't much difference.I agree the air gap may be your soloution.
never heard of a divider in a single plane not sure how you'd benefit from it.

 

Hard to imagine a dual plane being better with 4.88 gears. The Strip Dominator is one of the best smaller single planes out there. With 4.88 gears you go through dual plane type RPM in a nano-second anyway. Have you tried raising initial the timing...like into the mid 20's or so? It can really wake up the bottom end and big intakes love it.

But back to your question....yes folks sometimes have put a divider in a single plane. It doesn't act like the average dual plane which have a main benefit of longer runners. Runners stay the same. It does somewhat increase carb signal by limiting the amount of carb throats each cylinder "sees"....but it also limits what they see at WOT which is one of the advantages of a single plane.

The Weiand dual plane will work OK. But again...their largest one isn't as "punchy" as the smaller ones...but help on the top end.

JIM

 

A good alternative should be an rpm type dual plane intake. It just has the center divider cut down a bit, to mimic the single plane a little at high rpm.

alternately you could get a dual plane with a full divider and stick an open carb spacer on top of it or two if you want more open space. If you got the space under the hood that is.

 

A divider just splits the plenum in half.......the true "180" manifold signals the carb every other cylinder in the firing order in sequence and that is where the improved signal comes from.
A really excellent intake is the ZZ454/502 piece.......I would go that way. Or even a factory piece with a slightly milled divider or RPM Air Gap.......all will function very well.

Jebby

 

I agree with your state of tune up the timing, carb adjustments, and carb type are really your problem. I can't imagine a BBC having problems with low end TQ just because of a intake type. Oh a thought just came to mind....... do by chance do you have the 390 HP 427? Very disappointing engine to ever put in a Vette.

But back to the question of installing a divider in a single plane. I only had 355 ci in a 7200 rpm red line single plane equipped. I was talked into installing the new 750 CFM demon double pumper. It just had nothing down low in rpm. so I though why not machine slots and install a .080 aluminum divider. Yes, I was even so smart that I used JB weld to seal and round out the bottom plenum transition. All that crap and engineering eventually got wasted the first time I had a simple manifold backfire or even just intake pulses. but I didn't realize it for a period of time. Many miles later I pulled the carb off. the back fire had bent the divider plate sideways. Enough to come out of the slots I surmised. Intake valve openings create terrific plenum pulses and it worked that aluminum back and forth until all the JB weld fed through the motor. What was left of the aluminum was all rounded like a piece of drift wood on the beach.

Did it work??????? maybe somewhat, but I was also getting a handle on timing and carb adjustments. the real fix would have been just going back to the original Edl VS 750 carb or a smaller cfm double pumper. I really think that modern single and dual planes are so much better that they just work. I'm a single plane guy on my vette since the 80's.

with 4.88's I'd be looking at a 5 or 6 speed OD

 

I see in your profile you have an L88 hood so you have hood clearance to run many different manifolds.
However the lack of low-end TQ and coming-on at 4000 is a problem.
I too smell a initial timing issue.

How big is the cam?

 

Thank You for the responses. I bumped the timing up and it helped a lot. The cam is an old solid lifter(I didn't realize how old til just now) Crane that I bought in 1980. The lift is .597 and I don't remember the duration, 260 or 280ish I think. I need to quit looking at it and spend more time driving it. Thank You again for the responses

Rick
Big Block 69

 

That's what I get yelled at for almost daily, that I don't drive it enough, but this new cam really makes it more fun. But I have an 2018 expidition with 500 wheel horsepower that's just so darn fun to drive, it is hard to choose.