[chiphead]

Going to run a Q jet, spreadbore nitrous plate and a RPM intake on my 434. Do I need to notch or otherwise modify the divider on my RPM intake when using a plate?

[chiphead]

Nobody?

Is notching the divider not required when running a nitrous plate or carb spacer? I assume the extra space between carb and intake helps the sides of a dual plane intake "see" each other?
Would you not want to notch an intake used with nitrous, to prevent a cylinder from stealing mixture?

[Tom Vaught]

If you use a spread bore nitrous plate, my opinion is you would need to modify the plenum walls to remove the "step" from the Q-Jet pattern to the Square Bore Manifold inlet.

If the Nitrous Plate is the typical thickness, the Throttle Blades should be high enough to clear the side walls without issue. You do the mod for air flow, not for clearance for the throttle blades.

The divider wall (with the NOS plate height), should allow for the rear blades to clear the center divider.

Tom V.

[chiphead]

So basically I would need to lay back the intake's carb pad so it matches the contour of the plate's outer walls?

[Tom Vaught]

Yes

TV

[blueghoast]

I ran a RPM with a n- plate and a 4150 carb for years with no problems.
You should be fine.

GT.

[Tom Vaught]

Originally Posted by blueghoast

I ran a RPM with a n- plate and a 4150 carb for years with no problems.
You should be fine.

GT.

Agree, RPM manifold is designed for a Holley carb.
Nos plate probably designed for a Holley carb and RPM intake.

He is trying to run a Q-JET Carb with a Q-JET NOS Plate on a square bore manifold.

The center divider will not be the issue, the issue will be the edges of the intake opening.

Tom V.

[PAUL K]

It would be a good idea to thin the plenum divider some. Most spray bars have a few discharge holes pointed directly at the divider walls.

[surfsama]

Originally Posted by Tom Vaught

Agree, RPM manifold is designed for a Holley carb.
Nos plate probably designed for a Holley carb and RPM intake.

He is trying to run a Q-JET Carb with a Q-JET NOS Plate on a square bore manifold.

The center divider will not be the issue, the issue will be the edges of the intake opening.

Tom V.

I could be misreading the OPs post but if he's talking about an Edelbrock Performer RPM manifold it has a spreadbore configuration (at least for the Pontiac engine).

[chiphead]

Correct, the RPM accepts spreadbore carbs but has the 4150 bolt pattern too. I did lay the opening back and knife edge the center divider to clear the spraybar pattern. I had to gouge and blend the carb pad at the ends of the center divider, so the spray pattern will spray down the plenum.

[Tom Vaught]

Picture says a Lot. That looks really good now. Glad you posted the picture and I can see that you are using a Holley Spreadbore NOS Plate. Totally slipped my mind about you posting the NOS Spreadbore plate being there. DOH! So used to Squarebore Holley stuff.

Tom V.

[Skip Fix]

I've still got an old Moroso Qjet N2O plate system I put on my 78 TA when I had the stock motor. Felt like another set of secondaries kicking in-which that 180 HP motor needed!

[HWYSTR455]

Originally Posted by chiphead

Correct, the RPM accepts spreadbore carbs but has the 4150 bolt pattern too. I did lay the opening back and knife edge the center divider to clear the spraybar pattern. I had to gouge and blend the carb pad at the ends of the center divider, so the spray pattern will spray down the plenum.

That's what I did too, just like you did, laid the plate on there and smoothed all transitions, and knife-edged the divider. 4150-type carb tho. I ran a NOS Cheater plate initially, then went to a NX perimeter plate, but never filled the bottle. I had no issues though with the gap from an open plate with the RPM (with a 4150).

.