Doesn't start up straight away

I drive my vette to work twice a week and use it once on weekends.
I cover it in a 'breethable' cover the rest of the time.

ok, now to the problem, It is a '77 with a fairly new engine (1 year
old GM 350)
It doesn't start up right away sometimes.
I usually pump the accelerator pedal once before starting and twist the
ignition.
It usually catches 3 out of 5 times. Other times I either get a petrol
smell or the godawful cranking from the starter. I let it sit sometimes
10 mins before starting her up again.

But sometimes, I just floor the accelerator and turn the ignition till
it catches. Then of course the engine springs to life and the car
shakes and a ton of smoke comes out the exhaust.

It runs perfectly after that. I guess it's the cold engine or
something, but I need to know.
What am I doing wrong ? Or am I just not pumping enough before start ?
or flooding it ?

"E_Tar" > wrote in message
oups.com...
>I drive my vette to work twice a week and use it once on weekends.
> I cover it in a 'breethable' cover the rest of the time.
>
> ok, now to the problem, It is a '77 with a fairly new engine (1 year
> old GM 350)
> It doesn't start up right away sometimes.
> I usually pump the accelerator pedal once before starting and twist
> the
> ignition.
> It usually catches 3 out of 5 times. Other times I either get a
> petrol
> smell or the godawful cranking from the starter. I let it sit
> sometimes
> 10 mins before starting her up again.
>
> But sometimes, I just floor the accelerator and turn the ignition
> till
> it catches. Then of course the engine springs to life and the car
> shakes and a ton of smoke comes out the exhaust.
>
> It runs perfectly after that. I guess it's the cold engine or
> something, but I need to know.
> What am I doing wrong ? Or am I just not pumping enough before start
> ?
> or flooding it ?
>
Just a guess but pump it once and then hold it about 3/4 open for a
bit and let the mechanical linkage and choke set. Then crank it over
at an idle throttle position. Remember your engine temperature and if
that don't work pump it twice the next time. What works on a cold
engine doesn't always work on a hot engine when it's naturally
aspirated so adjust the procedure with the engine temperature.

--
Dad
05 C6 Silver/Red 6spd Z51
72 Shark Black/Black/4spd

Oh in addition, when the car does start, when I put it into gear i can
hear a thud and the car jolts a bit, then i reverse and when I put it
into forward gear, it jolts and thuds again.. This is not an engine
noise, it is transmission.. Do I need to replace anything ?
If it's normal then i'm just being paranoid.

I guess the reason I haven't put a stereo in yet is so I can monitor
the engine noise at all times for something out of the ordinary.. I
guess I get carried away sometimes.

keep adding to my vette page by the way, check it sometime.
www.eslurf.com/corvette

E_Tar
77 Stingray

Quote Dad
"...pump it once and then hold it about 3/4 open for a bit.."


but wouldn't that flood it ?

it's a carborator, if it is cold, pump it at least 3 times then try starting
the car. It is not fuel injected, when cold there is no fuel in the system
it has evaporated, so the intake and carborator will be dry inside until you
press on the peddle.


"E_Tar" > wrote in message
oups.com...
> I drive my vette to work twice a week and use it once on weekends.
> I cover it in a 'breethable' cover the rest of the time.
>
> ok, now to the problem, It is a '77 with a fairly new engine (1 year
> old GM 350)
> It doesn't start up right away sometimes.
> I usually pump the accelerator pedal once before starting and twist the
> ignition.
> It usually catches 3 out of 5 times. Other times I either get a petrol
> smell or the godawful cranking from the starter. I let it sit sometimes
> 10 mins before starting her up again.
>
> But sometimes, I just floor the accelerator and turn the ignition till
> it catches. Then of course the engine springs to life and the car
> shakes and a ton of smoke comes out the exhaust.
>
> It runs perfectly after that. I guess it's the cold engine or
> something, but I need to know.
> What am I doing wrong ? Or am I just not pumping enough before start ?
> or flooding it ?
>

"E_Tar" > wrote in message
ups.com...
> Quote Dad
> "...pump it once and then hold it about 3/4 open for a bit.."
>
> but wouldn't that flood it ?
>
Nope, nothing happens unless you keep pumping it, note the term
"pumping". That's why I said pump it once, if that is not sufficient
pump it twice the next time. There is about a 1/2 diameter piston like
pump in the carburetor the squirts 2 jets of raw fuel into the cold
manifold, one on each side. The way to flood it is to just keep
pumping or if the choke sticks. As you hold the throttle open the
linkage is free to set its self to fast idle speed and sets the choke.
Now you can crank it and when it starts it should be on fast idle if
you let off on the pedal as I said before you started it. Until the
choke stove warms up and a bimetal spring warms up and pulls the
linkage back to a normal run speed the fast idle will be maintained
until you kick it off by blipping the pedal.

On my 72 Vette (350/4 spd) and 54 Pontiac with a 400 cid sbc t350 tranny,
all you do is pump it once and it fires up right away. After sitting for
weeks!

The problem is that the choke is not set properly. You should have a
quadrajet carb on the 350. You need to pump it once to set the choke closed
and to put a squirt of gas in the line. As you crank, the vacuum should
open the choke a little bit (usually set with a drill bit) to the first
fast idle knotch which also has a fast idle rpm adjuster screw.

After the car warms up, the electric choke coil or intake manifold choke
coil oven will heat up and then you have to kick it down to release the
fast idle and get to the slow idle setting.

Most garages don't like to spend the time to set up a quadrajet because to
do it properly can take a couple of days. You have to have the engine cold
for the cold engine settings and hot for the normal idle. It takes me a
couple of days to get everything right. Most is waiting for the engine to
cool down so that I can test it again.

There are 3 functions of the choke:

1. Initial startup where it is closed completely so you can suck in as much
fuel as possible.
2. Once its fired, the choke opens a little bit to let the engine run at a
richer mixture than normal.
3. Once its warmed up, the choke opens all the way for a normal mixture.


E_Tar wrote:

> I drive my vette to work twice a week and use it once on weekends.
> I cover it in a 'breethable' cover the rest of the time.
>
> ok, now to the problem, It is a '77 with a fairly new engine (1 year
> old GM 350)
> It doesn't start up right away sometimes.
> I usually pump the accelerator pedal once before starting and twist the
> ignition.
> It usually catches 3 out of 5 times. Other times I either get a petrol
> smell or the godawful cranking from the starter. I let it sit sometimes
> 10 mins before starting her up again.
>
> But sometimes, I just floor the accelerator and turn the ignition till
> it catches. Then of course the engine springs to life and the car
> shakes and a ton of smoke comes out the exhaust.
>
> It runs perfectly after that. I guess it's the cold engine or
> something, but I need to know.
> What am I doing wrong ? Or am I just not pumping enough before start ?
> or flooding it ?

Thanks for all the input, I am not sure I really want to touch the
carb, or even open it up myself. The thought of losing or messing up
any precision part in there would give me nightmares. Dad's idea worked
and the car starts up after pumping and then tapping it once once it
catches.

Just out of curiosity, how much does it cost to convet to EFI and what
needs to be removed ?

E_Tar
('77 Stingray)