Wonder why single plane intakes run, start and idle better than dual plane intakes on a big block?


Veteran Member
Feb 25, 2002
memphis, tn-shelby
Going to put a stock hood on my big block Vega so I took the air gap off and put an old Edelbrock Streetmaster on it. Love those intakes and gained about 1 3/4 more room.
Damn car, idles runs and starts better.
It’s happened with with my 69 and 70 Camaro too.
Obviously air gaps are great intakes but single planes just seem to run better on my 454s. Streetmaster, street dominators and strip dominators. All just run better than dual planes for me.


Veteran Member
Sep 8, 2015
Perhaps it’s the DP inherent port runner design and stronger pulse signals that highlights or magnifies some carburetors “quirks” and/or perhaps a poorly adjusted/machined idle, trans/bleed circuits.

I’ve seen this as well. Sometimes calming things down with an “open plenum” just balances things out, and the engine ends up just in a happier place with he open plenum.

GM never used an open plenum in the HP sbc or bbc, it would of been less expensive to produce, must of been a reason.


Veteran Member
Jun 17, 2006
Ah, my BBC's with dual plane intakes start great in cold or hot weather, might be the carburetors are maybe not right when one has a hard starting issue. The reason I think your car starts better is that Streetmaster intake has small runners and a smaller plenum area for a stronger signal to the booster, but if it works for you that's what counts. Who the hell would want a BBC in a Vega?, 🤣 Just funning with ya, it's probably a pretty cool ride.


Veteran Member
Sep 4, 2013
Oviedo, Florida
GM finally gave in and only offers the ZZ6 with a single plane. There really aren't any drawbacks to a single plane other than low rpm torque loss. In reality I haven't found there to be much torque lost with a low rise dual plane vs a low rise single plane.

Speaking of, I was thinking about swapping the 882s and Chinese dual plane (it was free) on my GMC for some Chinese heads and my Scorpion intake. It's very tempting.


Veteran Member
Lifetime Gold Member
There are way too many variables in engines to make blanket statements about one being better than the other, especially on SBC vs BBC, unless you are assuming that SBC has higher rpm range. In any sort of street motor that is running generally lower rpm, a dual plane should generally be fit for purpose.
Hit this link if you want more info and science than you need.


Veteran Member
Feb 8, 2007
Poconos P.A.
There is absolutely no inherent advantage to a dual plane intake on anything remotely describing performance.

As was mentioned in this post in a round about way , a dual plane intake is a crutch to get better drivability out of a given engine , hence why the bean counters at the OE used them .

And as a "P.S" to the OP , Big block Vega ?? We defenently need pictures :)