Hot Rod Forum banner

Just bought 78 Camaro Z28, quesiton on changing 2 barrel carb to 4 barrel

7K views 8 replies 6 participants last post by  cobalt327 
#1 · (Edited)
I have purchased a 1978 Camaro Z28. It has a 350 engine, but a 2 Barrel carb. I am going to change this to a 4 barrel setup, but need to know what I need to do to get this done. I know I need to change the Intake Manifold. I am going to purchase an Edelbrock Performer II intake, I am not sure about the carb. I do have a Carter Carb, Its a Competition Series, I can provide the number on the carb if needed. And do I also need to change the Heads on the motor? I do have 4 spare 350 Heads in my garage, I will need to have two of them machined before installing. Please can someone let me know if I just need to change the intake manifold to install the 4 barrel carb, or Do I also need to change the Heads as well.

thanks in advance, Much appreciated.
 
#2 ·
Just need a 4BBL intake and the carb, if your staying stock i would go with about 500-550CFM, and also you might want to look into going with some headers, if it has stock manifolds that go into a single pipe, it makes your engine into a pig from my experience.
 
#3 ·
Upgrade from the rear of the car forward.

Start with rear gears/limited slip
Lots of highway time-3.23/3.42
Just cruising town/strip-3.73/4.11

Then suspension upgrades, stiffer/lower springs, better shocks anti-sway bars, new bushings.

Next better flowing exhaust systems, I believe that 78-older cars are emission exempt so cats are optional. I would run ceramic coated long tubes 1.625" pri.3" coll. and a dual 2.5" and then chose mufflers based on what sound you like.

Once these are performed you will have a vehicle that will respond MUCH better to any upgrades you make in the engine compartment.

I'm quite bothered by your "typical gearhead" who bolts on a bunch of chrome and a 4 bbl carb and then insists they have something special under the hood........nothing special about a polished TURD.

If the engine is all original in your ZEE, than it should be equipped with a 4bbl quadrajet. Although it is a real possibility that someone unwittingly replaced the venerable quadrajet setup with a lesser two holer.

So the fact that GM had intended for your engine to be inducted through a 4bbl is a good thing, it will likely respond well to being returned to it's stock configuration or something similar, perhaps a holley in place of the factory q-jet. However, even with a 4bbl carb your cars engine is rated at 185 GROSS hp, which means that your likely only putting down around 100hp at the wheels.
 
#4 ·
yeah 78 is exempt, cats are optional, but he should have 3.42 gears in the rear end if it IS a Z-28 (been building camaros for a while) and while all the suspension work is nice, in my oppinion if you have the money, great go for it, but if you dont, take it for a spin, if she feels decent, wait untill your in a financial position to do that.
 
#5 ·
Be careful about what you take off the car. A '78 doesn't have to go through emissions testing, but you still have to pass the safety inspection.

And as part of that inspection they'll check to see if you have the emissions equipment in place. They won't check it to see how well it's working, but if they look for what's supposed to be there and don't see it then they can and will fail you.

Where I live in Texas, I've noticed the shops have gotten a lot stricter about going by the book, as DPS has apparently been cracking down on places that are being too casual.

I'd definitely get rid of the stock cat. Those '70s GM cats are like a cork stuck in your exhaust. But you can get an aftermarket cat that flows pretty well.
 
#6 ·
Juicer28 said:
Please can someone let me know if I just need to change the intake manifold to install the 4 barrel carb, or Do I also need to change the Heads as well.
The intake, carb and the bracket for the throttle and kickdown will be needed, along w/a gasket set.

I would use the aluminum factory intake w/a Q-jet carb. If you choose to go w/the Edelbrock Performer (an OK intake, but nothing special on an otherwise stock engine, IMHO), you can still use the Q-jet.

If you use a square bore carb like the Edelbrock or Holley on the 2101 Performer, you'll need the metal spacer #2732 or a 1/4" thick insulator-type gasket to assure there won't be an intake vacuum leak at the carb base.

If you know you want a square bore carb, get the Edelbrock EPS intake. Either of these intakes will require a throttle/kickdown bracket like the Eddy #8030.

Be sure to position the engine @ TDC and note whether the rotor is pointing at #1 or #6 so the distributor will be easy to reinstall. Do NOT crank the engine over once the distributor has been removed, or you'll have to start from scratch to reinstall the distributor correctly- this is something that gives problems all the time, so avoid the whole issue by doing things correctly from the start and you'll be fine.

Don't forget a low restriction 14" x 3" or 4" tall element air filter.
 
#7 ·
Thank you for the info, I have learned not to trust anyone who says, they know what they are doing. I am handicap, and now in a wheelchair, My son is going to be helping me. I also have a 1980 Camaro, and It has the edelbrock Intake. The guy who helped, said he knew how to handle that job. I arrived home one day to find him working on my car. I saw he had removed my original Intake, I then went into the house, Well the next day I learned he failed to make note where my dist was when he removed it. That has caused me to start from Scratch, I tell ya,, I was only 16 when i did my first intake replacement and I was smarter than he was,, I made note where my dist was once it was TDC, and I had no issues what so ever. Well, this was not the story on my 80 camaro. Never again will I go away while someone removes my intake. Thanks guys for the help, work will begin soon on my 78z28. I have given my 80 to my son.
 
#8 ·
stroker_SS said:
Upgrade from the rear of the car forward.

Start with rear gears/limited slip
Lots of highway time-3.23/3.42
Just cruising town/strip-3.73/4.11

Then suspension upgrades, stiffer/lower springs, better shocks anti-sway bars, new bushings.

Next better flowing exhaust systems, I believe that 78-older cars are emission exempt so cats are optional. I would run ceramic coated long tubes 1.625" pri.3" coll. and a dual 2.5" and then chose mufflers based on what sound you like.

Once these are performed you will have a vehicle that will respond MUCH better to any upgrades you make in the engine compartment.

I'm quite bothered by your "typical gearhead" who bolts on a bunch of chrome and a 4 bbl carb and then insists they have something special under the hood........nothing special about a polished TURD.

If the engine is all original in your ZEE, than it should be equipped with a 4bbl quadrajet. Although it is a real possibility that someone unwittingly replaced the venerable quadrajet setup with a lesser two holer.

So the fact that GM had intended for your engine to be inducted through a 4bbl is a good thing, it will likely respond well to being returned to it's stock configuration or something similar, perhaps a holley in place of the factory q-jet. However, even with a 4bbl carb your cars engine is rated at 185 GROSS hp, which means that your likely only putting down around 100hp at the wheels.
Amen to all that; Yes, one thing that annoys the heck out of me(not sure why) is that the first thing EVERYONE AND THEIR BROTHER does when they get a chevy, if it has not been already done, is to discard the stock q-jet and manifold and replace it with a holley----resulting in no appreciable benefit and a lot of times decreased performance.

i totally agree with modifying a car from the rear axle forward. Actually, if i had a camaro or any unibody car, the first thing i would do would be to install subframe connectors before doing anything else. Weld in, not bolt in.
 
#9 ·
Juicer28 said:
I have purchased a 1978 Camaro Z28.
Be sure you actually have a Z/28- there were a ton of the base models "cloned" (often w/nothing more than a V8 transplant and a set of stripes), then sold to unsuspecting buyers at a premium.

There are many differences between a Z/28 and a lesser Camaro, some subtle some not so subtle- like the aforementioned stripes. Take the time to see exactly what it is you have before going all-out on a restoration. Hopefully you bought it as a decent driver rather than some sort of investment.

You can tell if the engine is original to the chassis by matching the VIN to the partial VIN on the passenger front of the block, behind/under the alternator (example below). If your block has been decked, the numbers may have been removed during the process. The block casting numbers and date code will also help to determine the block's origin.


SUFFIX CODE/PARTIAL VIN PAD




Good luck.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top