Hi guys. I am restoring my 1970 Chevelle SS LS6. The motor is being rebuilt to the original specs. I prefer the original appearance of the factory engine components. I have decided not to use the original A.I.R. pump and exhaust manifolds, but I am going to use headers. This is the only aftermarket part I care to use.
I have the original dual plane aluminum intake manifold and an aftermarket single plane aluminum intake manifold. My question is, would I notice much difference in performance between the two manifolds. I plan on showing the car and occasionally want to pull a few RPM's. Would the headers make up the difference. What are your thoughts?
Thanks, Curtis.

Me personally,I'd keep the original LS-6 manifold on the car.If you where to put on an aftermarket intake,I wouldn't use a single plane..you proably be better off with a Performer RPM.

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1970 Chevelle SS396/L78/M21/4.10 My 70 SS396 (http://www.chevelles.com/showroom/mr4speed70SS1)
1982 Oldsmobile Cutlass 350 Olds,TH350(daily driver)
"Be aware of the possible ramifications of the potential outcome"
Chris Corwel,the man from the too much taxes and over priced gas state of Connecticut
TC Member 785

i too would stick with the original intake. there is not that much difference in performance.as a matter of fact.the after market intakes are basicly takeoffs of the factory g.m. piece's and i've run in the 11s with a 163 casting intake,with the only mod done was port matching.

Curtis, stay with the original dual plane. First because your building to origianl specs. Second you said except for headers and deleting A.I.R. you prefer the original appearence look. Therefore you don't want to relocate the coil and bracket, reconfigure the vacuum source for your power brake booster, eliminate heater and by-pass hoses, have no provisions for your divorced choke linkage to name a few. Besides that dual plane will have far better throttle response and driveability not to mention that if you were to run it down the quartermile it will ET better too.

Pulling a few RPM's is more about the design perameters of your buildup than what manifold and headers you are using. If your staying with the stock LS6 flat tappet mechanical cam 242/242 @.050 with .520/.520 lift you'll have more than enough RPM with a 6000 - 6200 RPM shift point and 6800 RPM redline.

There are however better flat tappet cams available today both hydraulic and solid lifter versions that will make more power yet operate within the same powerband of the original grind.

As for headers I recommend going with 1 3/4" primary tubes with 3" collectors. Dynomax, Hedman or Doug Thorley have well built headers that fit without major struggle, modifications or headaches.

[This message has been edited by racer1320 (edited 01-06-2001).]

I hope everyone here realizes that intake he has is the pancake intake or flat. The other intakes 65-69 were high rise dual plane aluminum intakes. I would not go with a single plane intake because you need the torque to pull that heavy Chevelle.

I would recommend the GM factory hi-rise alum intake that came on all the hi-per engines. Make sure the intake divider isnt machined out. That low rise original intake is a choker, the runners actually extend below the intake ports into the lifter valley
and the airflow has to make a bunch of turns, hurts power. This manifold was designed for low hood clearance on vettes and novas, the chevelle will clear the factory hi rise, no problemo. Also you can use the factory oil slash shield that clips under the intake, block the heat passages with appropiate aftermarket intake gaskets. The performer will fit also but the factory manifold looks more OEM, I've noticed no difference in power.

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http://msnhomepages.talkcity.com/yosemitedr/quintillis/index.html

plain, I'm with you on that. But he's doing a stock rebuild and wants stock appearence. Just not worth spending the money for a high rise for what he is doing because he'll never "feel it" on the street. Besides plenty of LS6 Chevelles running A/SA, B/SA in NHRA Stock Eliminator competition using this manifold running in the 10's.

I agree with Glenn on the high riser version though providing he can get it cheap. The lifter valley splash shield is a must. This is one of those "secrets" to making power.

[This message has been edited by racer1320 (edited 01-06-2001).]

I glad to see you running headers. I like a full resto too, but if its going to be driven why give up 50 HP !! I tend to agree with the rest of the guys on the manifold issue. High rise factory job, leave the singles to the light weight/ 4 speed guys guys ( 3200 lbs or less)

just my $.02

Thank-you to all that have posted information. I enjoyed reading all of the messages and I will be placing my LS6 intake back on the car.
Much appreciated, Curtis.