L48 intake issue
Thread Starter
Instructor
Joined: Mar 2009
Posts: 157
Likes: 16
From: Yorktown VA
L48 intake issue
I just had my 79 L48 rebuilt, bored to 383, put a slightly beefier cam(magnum cam), with some blueprint aluminum heads, for a little more power, and already have hooker headers and side pipes, and a 600cfm Edelbrock performer carb as well. I know it was a numbers matching car, that's why I opted to rebuild the engine instead of get rid of it.
The thing is I'm still hungry for more power. I can squeal the tires, which is fun, but Id like a bit more which brings me to wanting to get a new intake. After some research I want an edelbrock performer. I have read so much about that with a performer intake not being able to fit under a stock hood and how it can with a dropped base. I haven't been able to find the stock height for an L48 intake thought and I think this would solve the mystery for me if I have some hard numbers.
Or just some people that have done this same thing before?... Id love some help thanks for everything.
The thing is I'm still hungry for more power. I can squeal the tires, which is fun, but Id like a bit more which brings me to wanting to get a new intake. After some research I want an edelbrock performer. I have read so much about that with a performer intake not being able to fit under a stock hood and how it can with a dropped base. I haven't been able to find the stock height for an L48 intake thought and I think this would solve the mystery for me if I have some hard numbers.
Or just some people that have done this same thing before?... Id love some help thanks for everything.
Pro
Joined: Oct 2011
Posts: 743
Likes: 71
From: Jarrettsville Maryland
I was able to fit a Performer RPM intake under the stock hood of my 79 using the stock air cleaner and Edelbrock carb. I'm currently using a GM ZZ4 intake that gives even more hood clearance.
A Performer should fit just fine.
A Performer should fit just fine.
Last edited by dmruschell; Apr 27, 2017 at 12:26 AM.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 157
Likes: 16
From: Yorktown VA
Thread Starter
Instructor
Joined: Mar 2009
Posts: 157
Likes: 16
From: Yorktown VA
If you don't mind me asking why did you change to a GM ZZ4 intake rather then an edelbrock?
Pro
Joined: Oct 2011
Posts: 743
Likes: 71
From: Jarrettsville Maryland
I've also read that the current Perforners are designed to produce low end torque. It's also been said that Edelbrock makes the ZZ4 intake. But, who knows.
I'm sure the difference is minimal, though. There is a dual plane intake shootout that was done by a car magazine a few years ago that compared 20 or so intakes. There are differences between the 3 manifolds, but it wasn't a huge difference.
The ZZ4 can also be had cheap on eBay, much less than I've seen the EGR Performers listed for.
Im going to be putting a Performer EGR on a 75 I'm restoring (engine is being built for max power under 5500rpm), and started a thread with pictures of both intakes for comparison.
Race Director
Joined: Jun 2000
Posts: 10,049
Likes: 675
From: FL
Get the Performer RPM. It will flow better and fit under the stock hood with a dropbase aircleaner. Here is my info on the RPM Q-Jet under a stock hood. BTW, the Q-Jet is a much better carb than the Edelbrock "Performer" (renamed Carter AFB).
If keeping the Q-Jet, get the Performer RPM Q-Jet 7104. Everything bolts on just fine. Only issue is no provision for the hot air choke so convert the carb to an electric choke. If you use a dropped base aircleaner (my favorite is the Moroso Low Profile Racing air cleaner), you can fit a 3" filter under the stock hood. Only mod is massaging the filter base a little for clearance for the accelerator pump arm. You can see where I laid a long socket under the base and gave it a few taps.
Last edited by SteveG75; Apr 27, 2017 at 10:10 AM.
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Pro
Joined: Oct 2011
Posts: 743
Likes: 71
From: Jarrettsville Maryland
It sounds like a standard Performer (or Performer EGR) will be the best fit, though the Performer EPS manifold probably deserves a look if a Quadrajet is not to be used.
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 787
From: Lebanon Township New Jersey
You said your engine was bored to 383. Converting a 350 to a 383 requires boring and stroking - changing the crankshaft.
Is your car manual or auto? If auto, torque converter and rear gears make a huge difference in low end throttle response, i.e. burning rubber.
Is your car manual or auto? If auto, torque converter and rear gears make a huge difference in low end throttle response, i.e. burning rubber.
Race Director
Joined: Jun 2000
Posts: 10,049
Likes: 675
From: FL
The OP said they'd rather have more power at 2800rpm than 5000rpm. The RPM may flow better, but flow doesn't always mean better low end torque (it often means less low end torque in favor of top end horsepower).
It sounds like a standard Performer (or Performer EGR) will be the best fit, though the Performer EPS manifold probably deserves a look if a Quadrajet is not to be used.
It sounds like a standard Performer (or Performer EGR) will be the best fit, though the Performer EPS manifold probably deserves a look if a Quadrajet is not to be used.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 157
Likes: 16
From: Yorktown VA
I bored it but didn't stroke it, has the original crankshaft. She was just bored to a .030 to make it 383.
So your saying the original Quadra-jet Carb is better then a performer carb?...or is a Q-jet carb something different then the stock one?
Pro
Joined: Oct 2011
Posts: 743
Likes: 71
From: Jarrettsville Maryland
Sadly its an auto with a 3.06 back end, but here in the near future I will be putting a T56 Magnum in it. I know that'll change the Torque and power to the wheels but didn't think it would matter much with the intake.
I bored it but didn't stroke it, has the original crankshaft. She was just bored to a .030 to make it 383.
So your saying the original Quadra-jet Carb is better then a performer carb?...or is a Q-jet carb something different then the stock one?
I bored it but didn't stroke it, has the original crankshaft. She was just bored to a .030 to make it 383.
So your saying the original Quadra-jet Carb is better then a performer carb?...or is a Q-jet carb something different then the stock one?
I've put over 40,000 miles on Edelbrock carbs on my 79. They'll work just fine (though I am going to try out a Qjet on my 79 to see if I like it better... past experience with a Buick 455 was that the Edelbrock made more power than the Qjet, but that could have been a fluke). Most C3 Corvettes came stock with Quadrajet carbs.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 157
Likes: 16
From: Yorktown VA
A 350 with the original crank bored .030 over is a 355, not a 383. A 383 requires a different crankshaft, either out of a 400 SBC or one designed as a 383 crank.
I've put over 40,000 miles on Edelbrock carbs on my 79. They'll work just fine (though I am going to try out a Qjet on my 79 to see if I like it better... past experience with a Buick 455 was that the Edelbrock made more power than the Qjet, but that could have been a fluke). Most C3 Corvettes came stock with Quadrajet carbs.
I've put over 40,000 miles on Edelbrock carbs on my 79. They'll work just fine (though I am going to try out a Qjet on my 79 to see if I like it better... past experience with a Buick 455 was that the Edelbrock made more power than the Qjet, but that could have been a fluke). Most C3 Corvettes came stock with Quadrajet carbs.
I still have the stock rebuilt Qjet, I got the Edelbrock a while back thinking it would bring some more power...not doing my research I didn't even know still don't know the specs on the Qjet, (CFM ect)
Depending on which carb I use I think will help determine the intake as well, because the 1" conversion plate I have is killing me for space under my hood!!
Thread Starter
Instructor
Joined: Mar 2009
Posts: 157
Likes: 16
From: Yorktown VA
While were on the subject... is that the only real way I can get more real power out of my SB 350? Actually make it a 383 with a new crank and everything else it takes? Of course without supercharging any forced induction. ?...
Pro
Joined: Oct 2011
Posts: 743
Likes: 71
From: Jarrettsville Maryland
Yeah!... that's what I meant! 355! sorry I'm a bit new to this more serious stuff. I only bored it out and put new heads and cam on it.
I still have the stock rebuilt Qjet, I got the Edelbrock a while back thinking it would bring some more power...not doing my research I didn't even know still don't know the specs on the Qjet, (CFM ect)
Depending on which carb I use I think will help determine the intake as well, because the 1" conversion plate I have is killing me for space under my hood!!
I still have the stock rebuilt Qjet, I got the Edelbrock a while back thinking it would bring some more power...not doing my research I didn't even know still don't know the specs on the Qjet, (CFM ect)
Depending on which carb I use I think will help determine the intake as well, because the 1" conversion plate I have is killing me for space under my hood!!
Every Edelbrock intake that is made to accept a Quadrajet will also accept an Edelbrock carb. The ZZ4 intake will accept both, as well. So, a Performer (with or without EGR), ZZ4 or Performer RPM Qjet will all allow you to use the Qjet or Edelbrock carb without any adapter plates.
I personally would go for the ZZ4 or Performer (EGR) manifolds for hood clearance reasons, and being able to use a heat insulator gasket if needed.
Pro
Joined: Oct 2011
Posts: 743
Likes: 71
From: Jarrettsville Maryland
If you can spin the tires, more power is only going to spin them more.
Chsnging your rear gears from 3.08 to 3.55 or similar will help a bit. According to the 79 user manual, automatic L48 cars were supposed to have come from the factory with 3.55 gears. Though, that will mean higher rpms on the highway.
Instructor
Joined: Jan 2012
Posts: 216
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From: Tanunda South Australia
Put a big block 454 in it you can't beat more cubic inches
Race Director
Joined: Jun 2000
Posts: 10,049
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From: FL
If it a 355, the regular Performer will work fine.
The Q-Jet is an excellent carburetor. It is actually a mechanically secondary carb that has a spring loaded air flap that opens on demand so a well tuned Q-Jet will never be "too much carb" for the engine. Remember, GM used the Carter AFB (which the Edlebrock is based on) back in the '60's. They dumped it for the Q-Jet to get both better performance and better mileage.
The Q-Jet is an excellent carburetor. It is actually a mechanically secondary carb that has a spring loaded air flap that opens on demand so a well tuned Q-Jet will never be "too much carb" for the engine. Remember, GM used the Carter AFB (which the Edlebrock is based on) back in the '60's. They dumped it for the Q-Jet to get both better performance and better mileage.
