so '02 Magnum 360, stock heads, Comp #20-745-9 (212-218 (264/270), .480/.480, on a 114* LSA - a truck cam, and a 2300 2bbl Sniper. My Sniper sits on a 2bbl adapter atop my Eddy 7577 dual plane. The adapter has a contoured bottom to allow the flow to 'expand', but there is the immediate wall of the 4bbl right below it, and after lots of reading I'm thinking I should remove about an inch or more of the 4bbl center divider, maybe leaving a half inch remaining, and radiusing the upper edge.

This is a 'truck' application - my Mag 360 is essentially 'done' by 4500 rpm, and from what I'm reading there don't seem to be any real drawbacks, and potentially a couple pros. What I dislike the most is the 'gap' between the adapter and the intake - it just looks...'improper'. I have the intake off to replace the original lifters (with a fresh set of Viper V10 units from Top Line), and while it seems to run fine I'm just wondering about cleaning things up a little while it's open. Thoughts?

as-is configuration -


seems like a less-than-awesome setup -


intake as-is -


intent is to remove the divider as shown...


...to result in this -


...and what's interesting is the big block dual plane I had before had a 'reduced' divider from the factory -

since the intake is off already... but that's just me

I’ll just say that I ported a couple that were cut out and welded back in.

The ONLY real way to know is to test.....test......test.

Or read about it from someone else who tested it on a combo as similar to yours as possible.

well I can't test, and I was just surfing for some real-world feedback. Some other threads had indicated non-negative results, and I was just bumping the topic for any new revelations.

I think there was an article in Mopar Action a while back - late last year ? - that dealt with modifying that truck intake.

the question really is...'open it all up' or 'isolate the two sides' - I can use the open scenario described above (which I kinda-sorta already have), or, I can opt for an adapter like this and completely isolate the two halves of the throttle body to the two sides of the intake -


Hell I dunno... 🤯

Cutting the center divider almost always improves power a little in the higher RPM ranges, on dual plane intakes in my experience.
But you said your engine is done by 4500 rpm, so it would be a toss-up in my opinion.

agreed - there's likely power to be gained in the upper rpms, and the question tho is are there drawbacks on the low end by removing the divider - that's the big question, and that lends to fully isolated, or open, and pros and cons of each way. It may be 'unanswerable' without a dyno, and I'm not going to that level of effort.

For sure I wouldn’t trust a dyno for this test.

yah my main thoughts are on how much better (if any) the MAP sensor might function if the divider were trimmed down and there was a bit more(?) signal strength on it from 'all '8 vs a 'limited 8' - that's a question I'll have to ask Holley on Monday. I think tho that what I am also seeing is that fully isolating the two halves is not the best idea...

I've done many a dual plane 4bbl intake and cut the center to varying depths. Depth makes a big difference on HP/TQ. I now just add different thickness intake spacers. Works better and the intake is better for resale intact. So what you have with that 4/2 plate is a spacer. Add a 1/2" and see how it feels when driving uphill with a load.

...I had a good conversation with Holley Tech, and they have no problem with my current setup - apparently the gap between the adapter and intake is...for lack of a better term...a non-issue, and recommends to run it as-is. I would love to get the true 2-hole adapter and run it to see if there were any perceivable difference, but for my application it doesn't sound like there is anything to gain by that, so, unless y'all see something 'off' in the config or datalog I'll (continue to) run it as-is. The good news is by all accounts milling the divider would not benefit my low-rpm 'truck' application at all, and could actually induce low-rpm drivability issues, so I can forget about intake mods and just bolt it up. If, down the trail, I want to drop on a 2-hole adapter I can do that...but that'll be way down the trail.

Thanks all
- Sam