Corvette project car

[GoCougs]

How is a square bore carb better than a spread bore carb? It's 750 cfm.

It already has full length headers.

Part of it is what is available - most aftermarket performance manifolds and carbs are square bore (Edelbrock has some spread bore manifolds but looks like they discontinued their Quadrajet) and spread bore carbs are in general a PITA to tune and keep in tune.

[280Z Turbo]

I don't need a carburetor, I have a good one.

I think that the Rochester Quadrajet design is technically superior for a street vehicle. The smaller primaries, vacuum and mechanical secondaries, and 750 cfm rating make it a very under-rated carb, IMO. I guess it's not shiny enough for most folks.

The bigger issue with the intake is getting the hood to close. The Professional Products 52001 fits a spread bore carb and fits under a Corvette hood, so I'll probably get that.

[hotrodalex]

750 cfm is huge though - I use a 600 and my dad's Camaro has an 800 with performer rpm air gap intake and other similar level stuff. And even he thinks the 800 is overkill (he contemplated stealing my carb to see how it ran)

[280Z Turbo]

That's the beauty of the vacuum secondary, you can't really have "too much carb".

[Secret Chimp]

I'm forgetting my first gear tops out at 60, that's probably more of my problem...

[280Z Turbo]

I'm glad I don't need to worry about any of that automatic stall nonsense.

[GoCougs]

I don't need a carburetor, I have a good one.

I think that the Rochester Quadrajet design is technically superior for a street vehicle. The smaller primaries, vacuum and mechanical secondaries, and 750 cfm rating make it a very under-rated carb, IMO. I guess it's not shiny enough for most folks.

The bigger issue with the intake is getting the hood to close. The Professional Products 52001 fits a spread bore carb and fits under a Corvette hood, so I'll probably get that.

Unless it's been rebuilt and professionally tuned an out-of-box Holley or AFB with just a wee bit of work will outperform a Q-jet. The Q-jet will also take a lot of work to keep in tune.

Q-jet and T-quads came into being because automakers wanted a single carb they could slap on anything from a 318 to a 440. They also wanted automatic choke and provisions for various vacuum plumbing to fit all sorts of applications.

It's definitely possible to over do it with a vacuum secondary carb. Jetted for equivalent idle and A/F mixture a square bore 600 will perform better than a square bore 750 on a mild 302. The 750 will tend to bog and the secondaries will be slow to respond to throttle input. (The factory spread bore carbs tried to mitigate this with all the extra hardware). 

That manifold doesn't appear to be a great match for that bigger Summit cam.

[hotrodalex]

Holley's aren't good for cars that sit around for extended periods of time.

[Secret Chimp]

How's a 4Junk going to take more work to keep tuned than a Holley? I've had mine set up the same for a year now save for adjusting the choke every few months with the weather.

[280Z Turbo]

I kinda like the Comp Cams XE268H

CamQuest says it will produce 366hp @ 5500 rpm and 397 ft-lbs @ 4000 rpm. Not sure I believe that, but it would be fun.

[280Z Turbo]

10:1 should be OK with 93 octane, right?

[GoCougs]

How's a 4Junk going to take more work to keep tuned than a Holley? I've had mine set up the same for a year now save for adjusting the choke every few months with the weather.

Has a lot more parts.

[hotrodalex]

10:1 should be OK with 93 octane, right?

Yes.

[280Z Turbo]

Has a lot more parts.

Not really. It's pretty simple.

The biggest issue is the same with any carb. Clogs due to spoiled gas.

[hotrodalex]

Not really. It's pretty simple.

The biggest issue is the same with any carb. Clogs due to spoiled gas.

At least it won't leak out the side like a Holley.

[GoCougs]

10:1 should be OK with 93 octane, right?

Like most things in life it depends. With the motor you've laid out - mild/moderate cam, cast iron heads, and a carb - my hunch is many/most engine builders/shops would say 10:1 CR on street pump gas is quite risky. There are things that can help though:

Bigger cam (lots of duration and overlap):  mitigating max cylinder pressure (but bigger cams bring their own issues of course)
AL heads:  more thermally conductive (i.e., mitigate combustion chamber hot spots)
Polishing combustion chambers and using certain pistons:  mitigate combustion chamber hot spots
Port sequential F/I: more precise delivery of fuel into the combustion chamber

[280Z Turbo]

The more I look at the frame, the more nervous I get. I'm finding more and more anomalies.

Looking into buying a C3 frame and moving the body mounts for a C2 body. The NCRS crowd poo-poos the idea, so that probably means I'm on the right track.

This shows the differences:
http://www.71corvette.com/frames.html

Good C3 frames can be had for around $1200. A bargain compared to a $5000-$6000 new frame.

[Eye of the Tiger]

You should put it on a C7 frame.

[280Z Turbo]

Looks like the lower ball joints were in such bad shape that they were popping back and forth in the socket. The uppers feel OK, but I may replace them anyway. The front coil springs were also in bad shape. One side had a collapsed coil.

I was wiring brushing the control arm of the Corvette then I looked up and realized I was kicking up a huge cloud of rust and dirt. I think I may have the black lung now, but in the event I survive I think it will look pretty good when I paint it. I really wish I could sand blast it, though.

[hotrodalex]

Are they press-in ball joints or bolt-in?

[280Z Turbo]

They were riveted on

[Eye of the Tiger]

They were riveted on

The originals, then. Replacements will have bolts. Definitely just replace them all.

[Soup DeVille]

As I remember from doing the same job on Caddies, getting those original ball joints out was sometimes a pain in the ass.

[280Z Turbo]

White, tan, or black top? Original was white.

[hotrodalex]

What color is the interior?

[280Z Turbo]

Black

Used to be dark blue.

[Soup DeVille]

Black.

[hotrodalex]

Black.

[280Z Turbo]

[hotrodalex]

You should bring it to the car show I go to in Columbus every July.