I did a forum search and come up to Gun Jam’s issue, mine is the same but I was leaning more towards vapor lock still. Mine won’t die on the highway, just after I get it to start and if I take off.

My car is hard to start, 30-40 seconds of cranking, when warm. It sometimes sputters and dies when I give it gas or start it from a roll. I've since learned what it's going to do and I feather the gas to keep it alive.

I had another post here and applied everything the tips that were presented.

I put in a new tank (so that is clean), I replaced all my fuel hose with braided stuff, I rebuilt the carb and then purchased a new one all together, put in a new fuel pump with a filter before and after and also put in a psi meter. It reads 5 when the car is running. I also added a carb spacer. I did this all last weekend. I started it up, checked for leaks and drove it around, re-checked for more leaks and drove some more.

Car is getting fuel but it's still a bitch to start after its warm and sits for over a minute. Oh and I looked at the plugs, they look perfect according to a few plug websites, they are white crowned with the arm thing black. A tad bit lean and running hot I guess, if anything.

I was getting ready to replace the spark wires at least but those are only three years old, my 6AL box is four years old. My coil is mounted to a head, but it’s been like that for the past year (15k miles and no issues), I'm hoping these have a longer life span than four years.

Could it be something simple like my timing? The car backfires once in a while if I mash it from the start (like a 1 in 20), but I thought they all did.


James

 

ive had issues like these, mine car would refuse to start after sitting for 10-15mins after driving around.

even if you bought a new carb, even expensive ones like holley or edelbrock they arent always tuned right out of the box.

take off the air filter and start here up watch the choke see if it opens all the way when warm.

now turn it off and watch it, see how fast it closes.
if it closes within 5 minutes then somethings wrong (im assuming you have auto choke) im not familiar with all type but i know that my autolite has a bimetal coil that controls the choke depending on temperature.

it would help if you mention which carburetor you have on.

 

when warm and you expect it to give problems. do not start. remove air cleaner and open the top butterfly so you can see into carb and agitate the throttle per hand. only open once slowly. does it spray fuel into carb at this time? yes/no?

 

It's a Holley 670 Street Avenger with an electrical choke.

Kalli: I'm on my way to work and I will see when I get there what happens. If no gas is coming through the jets, that would mean that gas is vaporizing in the front bowl correct?

Should I get bigger jets or take apart the carb and look for blockage somewhere? Maybe the bowl is sticking? It's a new one right out of the box.

On the rebuild of my other carb, I put it together fine and when I started it up, it had two leaks....I screwed down on one of the front bowl screws and it stripped out from the main carb body..duh.

Here's a video of it before I leave to work, looks like the fuel level is right on (it started in one crank cold):

[vid]http://www.youtube.com/watch?v=btbBNws6l4g[/vid]

 

High under hood temps, volatile modern fuel mixes, intake manifold exhaust crossover, and fuel line routing are some issues that promote vaporization in the fuel line and carb bowl.

Timing advance affects idle temperature. Can run vac advance (if equiped w/ dist vac diaphragm of course) to full time vac or ported vac.

Lean idle mix will promote higher exhaust gas temperatures and will contribute to high under hood temps. I run a lean idle mix but my under hood temps are under control. what is your header temp during hot idle?

do you have a functioning exhaust crossover?
should be blocked except those living near the north pole.

have you already addressed under hood temps?

i like to get the choke out of the equation when diagnosing; thats why i like manual chokes. when diagnosing auto choke car I temporarily adjust choke wide open.

 

btw
my 351w starts easier w/ more advance.
have stock dist and not easy to find different mechanical limit arms..
most critical is all in total adv of course.
i'm running 36* all in.
would like to run 38* but i'm chicken.

to improve cold starts i run full time vac to dist diaphragm.
this maximizes idle advance.

 

I'll invest in that header wrap kit from O'Rielly's and I will richen my gas a tad bit. Used to be so rich that it was watering my eyes out sometimes. I figured out how to use the vacume gauge and tweeked the front screws on the front meter block perfectly but I guess it's runs too hot now.

Weird because it got over 100 degrees here during the summer, I drove over 15k miles last year, once to Mass and once to a 6,000 feet mountain in Ashville, North Carolina.

Thank you for your input though. I did everything else that you suggested.

 

i like to set idle lean also. My under hood temps are good so i only have to worry about not damaging header coating. no fun smelling rich exhaust fumes at drive thru.

you can measure header temp vs idle adjustment; the temp change is likely insignificant.

i ran that wrap in the past. it really cools things down; at the expense of header embrittlement. if i ran cheap headers i would wrap them; I've no interest in going back to a hot under hood car.

there is also the dreaded winter gas mix.

 

keep in mind that most if not all completely original carb cars back in the day would boil the fuel out of the bowl on the hottest days. was just a part of life.

how can you expect a vented bowl of gas atop a 200+F engine to just sit there.

in walks fuel injection and no more vaporization problems.

 

and in comes complicated stuff