RobfromME

Good afternoon, all,

I've been reading on the forums that some intake manifolds, despite saying they won't fit under the stock Corvette hood, will indeed fit the 1973 and later vettes since the hood is somewhat higher.

Does anyone have direct experience with this that they can share? I have a 1974 LS4 (454) Corvette. I am interested in using:

Edelbrock Performer RPM #7161 (oval) or #7164 (oval for Q-jet)
Weiand Stealth
Edelbrock RPM Air Gap #7561

Also, does anyone have legitimate flow data/characteristics for the original LS4 intake manifold?

Thanks in advance for your interest and assistance.

Regards,
Rob

Little Mouse

I can't tell you that a high rise dual plane can fit under your 74 with the
LS4 for sure or not, I will tell you this long winded story.

I ordered a new 73 LS4, 4 speed (same hood, engine) By the time it had
4000 miles on it I could not stand the lousy performance any longer,
Warranty or no Warranty the engine was going to change, without going into all the changes only thing left of the original was the two
bolt block, heads were changed to rectangle port, used a single
plane tarantula manifold, 850 dp holley and a factory 14 inch
drop base air cleaner, I shut the hood, its hitting the stud and
wing nut, I put a regular nut on the stud cut a hair off the length
of the stud that was enough to make it clear, if you do not
know what a tarantula single plane is, it was edelbrocks single plane
race manifold for the time of late 1973, it was as tall as
any of the factory high rise chevy dual planes of the time that
everyone liked to use. If edelbrocks dual planes are not taller then
the old chevy high rise manifolds I would say you can pull it off if
they are taller may not work. The factory air cleaners both
small and big block were designed to work with the low rise
manifolds and match up to the hood. So even if you had a shorter
height small block you call edelbrock ask them if a there high rise
manifold will work, they will automaticlly tell you it will not.

GRIZ73

I have a Edelbrock Torker II manifold on one of my 73' BB's with anormal hood. It works fine, but is a single plane and bottom end is not too exciting at 2500 rpm it starts working and gets better as rpms increase. I have an Edelbrock RPM Air Gap on my other 73 BB, but barely have clearance with aftermarket L-88 hood and drop base air cleaner and 2 1/4 element. Air Gap has much better kick from idle right thru the rpm range. I have another high rise hood with an air box that will eventually replace the stock hood. I hope it will be even better.

yellow-fever

I went through this same dilemma with the buildup of my 74 454 coupe. I wanted a low-rise aluminum manifold with a Holley bolt pattern that would fit under the stock hood. It came down to 2 choices: Torker II or factory LS-6 manifold. Of these two, I preferred the LS-6 because of its divided plenum (for low-speed response with my 3.08/auto.) as opposed to the open-plenum Edelbrock. Bought one in mint condition on Ebay for $600. The only problem is that it is rectangle port and my heads are oval (GMPP aluminum). So I have a local engine building shop epoxy the ports to make them work with my heads. The result was excellent (see photo). I have a 3/8' carb spacer on top of the manifold to allow for clearance for the throttle linkage, a LS-6 drop-base, and a 3" x 14" air filter. The cowl induction is not hooked up. It clears the stock hood easily.

c6silver

Get a TBI intake from an 80's or early 90's 454 and remove the "tbi adapter" ...it should have a Qjet flange and it's aluminum. Match port the runner openings to those in the heads, remove the plenum dividers (the front to back ones, like an aftermarket intake) and cut down the divider .500 between the secondaries only. After all that, go find an 800cfm Q jet at the junkyard on a Buick or Cadillac and send it to SMI, JET, or Greg Gessler for a rebuild, flow mods, and plating. You should be good to go.

EDIT : 87-89 TBI intake is NOT aluminum, which surprises me given the advent of CAFE standards in the 80s...you would think that an LG4 305 getting an aluminum intake would mean that a BBC in a truck would also like a weight decrease for gas mileage, but apparently not...

74 LS4-454

With my 74 454, I decided to use the 427/390 factory low rise Q-Jet aluminum intake, which I bought off of ebay a few years ago. Had it tumbled and it looks brand new. It's still wrapped and ready to install whenever the engine goes back together.... I also have 68 427
"215" heads that are completely done and ready to install with another cam. Someday it will happen......
I felt the aluminum factory intake was a good choice compared to the aftermarket choices, no need to worry about hood clearance......

trw

You might want to look at Weiand Warrior 8123. Oval port and about 1.5" taller than the pancake 68-69's, they say they will fit with a drop base cleaner, it is for both Holley and Q-jet.
I am using the 69 aluminum pancake now and thinking of switching.
The 569 rec port pancakes are repoped for about $299 if you want a Holley.
Terry

Super6

I was surprised to see your statement that the RPM Air Gap barely fit with an L88 and a 2 1/4" element. I have run an RPM Air Gap under an L88 hood with the factory drop base and a 3" tall element on my 427. Mine is an oval port version.

c6silver

The TBI intake retains EGR and cowl induction functionality, if you paint it orange it even looks looks like a factory intake, you don't need a drop base air cleaner and it retains the Q-jet so no need to make up new fuel lines, etc...swap on an alumunum water pump while you're at it and save even more weight. The only downside is the amount of porting needed since these are for "peanut port" heads and not full size oval ports.

Big Block Dave

A while back, another forum user put up pics of his 73 with a stock hood, Performer 2/0 manifold and dropped base air cleaner. I have since purchased a performer for my 74 LS4 car and intend to put it on sometime this century.

Every so often I poke around ebay and look at 73-74 cars for sale to see the underhood setup. I think Ive seen a street warrior under a stock hood, and also the old school factory gm aluminum high rise as well. Dropped base air cleaners are mandatory.

A while back I bought an old Holley Street dominator, which will easily fit, but Id rather run the Performer.

Andy Tuttle

Would all this info be the same for a tall deck 427?

c6silver

No, but there are tall deck (366 and 427) truck engines with Q jet bolt patterns that might work, although I think you'll give up the stock air cleaner/cowl induction for a drop base set up.

c6silver

Look at a factory '71 LS6 intake sometime and see how flat it is...lower than a Performer, and that's under a BB/LT1 hood to boot.

CiCiC3

Yes I have the same year and engine and it does fit but just barely with a square port Edelbrock dual plane performer. I have a double pump Holley carb and an air-cleaner that come down over the top of the carb. Had to go with a shorter air filter that is about an inch and quarter high. Also had to use a regular nut instead of a wing nut on top of the air cleaner. Good luck...

Beedub73

Would something like this help? Made by Spectre, I believe, in several different layouts. I just bought a '73 454 and have an L88 hood as well as the stock hood. I'm sort of leaning toward going back to the stock hood, but performance is important, so I'll keep the L88 if need be. I'm looking to put a better intake on, as well as potentially going to MSD Atomic Injection system.