Well, from what my dad says, he can just tell that the engine isn't running right and that it smells of gas. Of course my dad is the kind of guy that ran a drill bit through his leg and didn't go to the hospital saying "it's really no big deal". So if he said it smelled like gas, it was probably enough to be alarmed about.

I'm going to check the plugs on the next sunny day we have. My pops is a bit protective of his Vette, and doesn't want me dissasembling things with out him around.

You might be onto something with the vaccume leak. it's certainly the most plausible, though one of the things we had that corvette guy check were the hoses. Perhaps he might have missed a leak though, who knows? How might we check for a leak? and for that matter fix the issue?

One of the things I'm going to do is take it out and just let it run for a little while, after we pump the tank and put fresh gas in, just to see exactly what it looks and feels like.

In other news, I just looked at the 1973 rochester quadrajet portion of the service manual, and holy load of crap, Batman... I'll never be able to dissasemble the carb in this life time. It seems so complicated, yet all I want to do is check the seat and the float. How do mechanics do this stuff? esshhh... I guess I'm just going to have to learn what things like a metering rod is, or what a solenoid is. How come the float bowl doesn't even look like a bowl? I have a new found respect for mechanics. haha, sorry, this is just a rant proving my ineptitude.

 

Since you've been messing with carburators I'd check to make sure that you are using the correct mounting gasket for it, I seem to remember that there are bunchs of different ones and what came with your rebuilt carb. might not be the correct one for your motor, having the wrong one can cause vacuum leaks and poor running, along with trash, (rust etc) in the fuel tank, lines etc. Good Luck. Peace,,,Moosie

 

There really isn't much you can do to balance a small block without tearing it down so other than a bad harmonic balancer I doubt it's a balance problem.

My 350 used to start to shake a bit at around 80 to 90 MPH but it was due to the engine running rough at higher RPM..... I didnt see where you mentioned which engine is installed.

Hey Moosie!
If its a stock '73 it should take the plain thick paper style gasket, no metal, nothing fancy.

 

I would pull the vacuum line coming off the intake manifold to the headlights, brake booster, etc. (plug off the fitting of course). That should just leave the vacuum line to the distributor. You can plug that off as well if you want. This should eliminate any possible vacuum leaks in hoses.

See if the engine runs any better. I check for vacuum leaks on the engine by spraying carb cleaner or WD40 around intake-to-head gasket and carb-to-intake gasket. If the liquid sits there you don't have a leak. If it is sucked in you have found your leak.

My 72 had a thick paper gasket between the carb and intake BTW.

If engine is running better, you can plug vacuum lines back on and see if that makes a difference. You have lots of vacuum lines (but not as many as my 72). Any of these could be leaking and causing a problem.

Not to badmouth you or your dad's skills about the gas smell....many people haven't been around a carb car and aren't used to their "smells".

Good luck.

 

Some good points SS
I use a few sets of forceps and start by pinching off the hose to the rear of the carb and trace from there.

I also use a propane torch not lit on a very low setting to test for leaks, If the RPM increases, you have found a leak.

It can take a while to complete this process.

 

I'd say that that's the case, but as I said before, that this problem happened with the stock carb after 5 years of the vette's life: before anyone tampered with the carb. I'll check for it anyways, in the event it somehow isn't the right mounting gasket.

And SS we take no offense though my IS 67 and remembers cars with the stick steering wheel, so I'm sure he's pretty used to alot of things.

I will definately try your trick for testing the hoses. I can tell this is going to be a long and artuous process, haha.

In regards to which engine it is, I beleive it's the 350 ci V8 (ZQ3) - which I beleive produces around 190 bhp, on the generous side, of course. I want to get the hotter small block option, which I beleive is the 350 ci V8 (L82) which produces roughly 250 bhp. the large block is just too heavy for the amount of power it produces. The only thing that I dont like about the '73 is the power reduction due to the lower compression engines, but I beleive that's easily correctable if I really wanted to boost HP.

Is there anything I can do to correct the "rough engine" at high RPMs?

oh, and thanks alot guys for all the info, I'm really learning alot.

 

Do an advanced forum search on "L-48" by forum member Jackson. Or simply read any posts made by Jackson that relate to enhancing the L-48 engine if thats what you have.
There are many other members that are very well educated in making these engines more productive as well, Jackson just came to mind as one being able to get the most out of an engine on a budget.

Theres a lot more to learn about the engine and it's HP ratings, how they were measured back in '73 and how to get the most out of one for the least $$$$

Does this car even run at all right now?

Have you inspected it for rust, where has it been stored, indoors, outdoors?

Theres hundreds of things that can fail over years of neglect.

A C3 Corvette is usually a car that requires a lot of cash to get back to a safe running, performing vehicle if it has been sitting for quite some time.

My '73 sat for 11 years before the two previous owners dumped many thousands of dollars into it.
And I have put another 3 or 4 thousand in it myself.

I'm not trying to discourage you in the least but these old Corvettes are usually always in need of constant maintenance and care and it doesn't come cheap.

You need to know your priorities first.
Is there any rust?.... A huge issue on C3's

Keep reading all you can about the early C3 and take it from there

Keep reading and asking questions..... thats the way to learn about these wonderful cars

 

Well Bob, the vette was stored in our garage for all those years, and is in surprisingly excellent condition. The interior could use a make over... (I dont know what they were thinking in the '70's with the color brown) and it's getting a little raty in places, but that'll come later. I've seen no body rust to speak of. The car DOES run, however, my father didn't feel it was safe enough to drive until we fixed this problem. Asside from this problem, the car is in great condition, although not quite ready for a car show.

The way I see it, I'm doing society a favor by trying to preserve this marvolous, homegrown American sports car. And also myself, so I can ride in it. So really if it's a matter of money, it'll just be a matter of time until I save up enough. Besides, I like to tinker with things. So I'm by no means discouraged.

On a side note, my fiance' bought me a corvette book and in the '73 section it as a picture of a white '73 with colorado plates that reads "BOBS73".

 

Thats great news
Sometimes you cant get an idea of what shape a car is in from just a few posts.

 

You could also check the vacuum advance actuator on the distributor. If you pull the vacuum hose off the carb and suck on it the actuator should pull the rod on the opposite side (going into the distributor). If the diaphragm is shot you would have a vacuum problem and the timing would go out at higher rpm which could cause the engine to run rough at the higher rpm.

 

Brilliant, mark! Now that sounds like something someone could miss and not fix. thanks alot, I'll be sure to try it! By the way, that corvette as your default photo looks like it's seen better days.

And indeed it's very good news, Bob, because a working corvette is a good corvette.

 

[QUOTE=heirloomvette73;[/QUOTE]

I've seen no body rust to speak of.


I hope not it's fiberglass.

 

When you talk about the engine needing balancing, I can't help but think of it not firing a cylinder and giving you a rough performance.

I know you already didthis, but if you already double checked your plug gaps and plug wires and made sure they are all set and routed correctly, tripple check them.

I just pulled my 73 out of hibernation and it was running strong after a good fluid change and fresh gas. But while zipping around town I noticed a very distinct change in performance. Opened the hood and only after careful inspection did I see that one of the spark plug boots had come off.

2 Days later I changed the fuel filter and once again performance changed drastically for the worst. Checked a bunch of other stuff before I pulled the filter back out. Very simple to see the filter I put in for a 73 did not fit. It actually crunched in the fitting. I put the old stone filter back in and problem solved. Still have not check to see what year set up I have on my Vette. But I'm not the original owner.

 

I stand corrected, lyle, haha! It makes more sense now that they added the 5 mile and hour bumper in 73 to protect the FIBERGLASS body, because to my knowledge, fiberglass is rather expensive to repair. I should have known better!

And I'll be sure to triple check things. I'm going to do a once over, then if nothing is fixed a twice over, etc. I am determined! This problem will be fixed by the end of the summer, God willing. Then I'll have the honor of driving it, though pops doesn't know it yet.

Monday we start working on the vette. God help us all.

By the way, does anyone put turbines on older vettes? I've heard of people using superchargers, but never turbochargers. It's more of a curiousity thing, but perhaps one day she'll be getting 3 miles to the gallon and have alot of vroom.

 

actually, now that I think about it, the bumper was changed in 73 to accomidate some change in laws, involving something about bricks and bumpers... Oh I can't keep it all straight.

 

The Plug wires and spark plugs can also breakdown when under load (high rpm) or when they get warm (the heat causes a crack to grow) this would give you good performance when cold and BAD when all warmed up!

bad misfiring would also give you the gass smell - unburnt fuel will get into the exhaust.

<<<<----- That is my vette we had a HUGE storm a few months back and a tree decided to lie down on my 73 - so now I have some bodywork to do - rareish car on my side of the world (south Africa)

Good Luck

 

I think the bumper law was to protect pedestrians?

 

I'll throw in-- Mine developed rough running at higher rpms-- turned out to be a fuel restriction-- fuel pump, filter, lines ect....
check fuel pressure

 

When was the gas changed ? has it been sitting with the gas for long?
Could be alot of water in the gas if its been sitting long..

 

And by this you mean a mechanical failure resulting in fuel restriction and not one of those stupid things car manufacturers actually install, correct? Id didn't think of that, but obviously not getting enough gas could throw everything out of whack. I'll be sure to check the fuel lines etc. if everything else fails. Is it possible that they're clogged or something? How might I check all those items?

And holy crap Mark! Did you cry? I would have. No bumper in the world could prevent that, are you doing the body work yourself? By the way, I think it's cool that there's a vette running on another continent. I'm sure lots of people buy vette's and take them over seas, but you're the first I've heard of.

And I looked up the deal with the bumper in one of my corvette books. "A new federal law now decreed that every new car should be able to hit a concrete block front on at 5 mph (8km/h), then reverse out with all its lights and control systems intact." Well, that's what I found. For once the government made a law that aided in the creation of one of the coolest cars ever. It's a urithane bumper that added a few inches to the length of the car and also 35 lbs to it's total weight. But it looks like you could take all that weight back if you had gotten the alloy wheel option back in the day which removed 35 lbs.