[Calvin_Engineer]

Good Afternoon,

I am a new member to this site and proud new owner of a 1973 Chevrolet Nova. It has a 350 small block, a 350 turbo transmission, a Holley 650 cfm carburetor (4 barrel, double pumper), and a summit racing mechanical fuel pump, lines and connectors.

The problem I am having is starting it at different times and temperatures. When the car has been sitting anywhere from 8+ hours, it starts amazing. Even after driving it around for awhile and heating up the engine, if I shut it off and start it up, it fires up fine. However, I am having problems starting it up in during intermediate times, like 15-20 minutes after the car is shut off. Most of the information I have read leads me to think it is a vapor lock problem, but I want to get all of your opinions. What do you guys think? If it is a vapor lock problem, what is the easiest way to check/ correct it?

Thanks in advance for all of the help!

 

[sevenzeronova]

May be getting starter heat soak?

 

[Clean 65]

First of all, welcome to SNS!

Does the starter engage when the engine is hot? If it doesn't and will only start after it cools off for a while you might need to put a high torque mini starter in. I had to do this with mine and it solved the problem.

If the starter engages when it is hot and the car doesn't fire you have either a fuel problem, ignition problem or maybe both.

Just somewhere to start looking, good luck! :yes: :yes:

 

[Calvin_Engineer]

Clean 65, sevenzeronova,

The crank does turn over, very well actually. It just won't combust as easily as when trying to start it when the engine was just shut off and when it hasn't been running for awhile. It is just this 20 minutes to 4 hours in between. I am running some trials tonight trying to start it with different sitting times (15 minutes, 30 minutes, 1 hour, etc...) Any other suggestions?

 

[graymond]

Could be a vapour lock issue. If you open the hood and wait your 15-20 minutes, does it start?

Do you have headers? Is the fuel line close to the exhaust? Is the fuel line from the pump touching the engine?

Have you checked your starter wires? Might need to upgrade those to new ones.

In the olden days, if it was vapour locked, you pumped the throttle until the car would fire and start. If you flooded it, you held the pedal to the floor and tried to start it. This is the simplest way to find out that I know.

Ray

 

[Rich74custom]

whats the status on your Holley? How old is it? Id say look at the carb.

 

[cdahl383]

Just taking a guess from afar, but I know I had issues years back with hot starts where my starter would crank over slow. It always started, just sounded like the starter was going to die. I ended up having to put a heat shield over the starter/solenoid to protect it from the heat from the headers. Since then no problems.

Sounds like that may not be the problem though if its turning over like normal.

Where is your fuel line routed? Do you run a carb spacer or just a basic gasket?

 

[Calvin_Engineer]

I just concluded my study, it just confirmed my suspicion

My car sat in the parking lot at my work from 1:00pm-5:30pm (4.5 hours Ambient 104F, yes it was deathly hot outside) Started right up, less than a second of crank!

I drove the car to my apartment, parked it, turned off the engine (Waiting a few minutes, 195F). Started right up, less than a second of crank!

Waited from 5:45pm-6:00pm (15 minutes, 190F), hard start 4-6 seconds of crank.

Waited from 6:00pm-6:30pm (30 minutes, 180F), hard start 4-6 seconds of crank.

Waited from 6:30-7:30pm (1 hour, 165F), Started right up, less than a second of crank.

So according to what I have seen, it has a "hard start" (4-6 seconds) sitting about 15-30 minutes at around 185F.

In response:

graymond, I do have headers and the fuel line is routed over the valve covers and down the front passenger side corner wall of the engine compartment. The closest section of the fuel line is the fuel pump which is about 4 inches away from an exhaust pipe. Also, I checked each of the starter wires last Friday, they all produced an arc. However, I replaced all of the spark plugs with AC Delco's (.035 gap).

cdahl383, the starter cranks perfectly fine, its a good sound, it just cranks longer in this 15-30 minute window @ 185F. Again, the closest section of the fuel line is the fuel pump which is about 4 inches away from an exhaust pipe. I am not sure if it is a gasket or a carb spacer, how can I tell?

rich74custom, the holley only has 5,000 miles on it, it is hardly broken in.

Thanks again guys for all of your help so far! I hope this new information sparks some though (no pun intended lol)

 

[MBZTECH]

Post a picture of the engine compartmnet and fuel line routing. Where is you're coil mounted? RICK

 

[graymond]

In response:

graymond, I do have headers and the fuel line is routed over the valve covers and down the front passenger side corner wall of the engine compartment. The closest section of the fuel line is the fuel pump which is about 4 inches away from an exhaust pipe. How close is the fuel line to the valve covers? Heat rises and this may be enough to vapour lock


Ray

 

[Calvin_Engineer]

graymond,

The fuel lines are approximately 4 inches away from the valve covers at the closest section.

MBZTECH,

The coil is an Accel HEI. It is located directly behind the Holley.

Please see the attached link below for the pictures in my garage.

http://www.stevesnovasite.com/forums/garage.php?do=viewvehicle&vehicle_id=1640

 

[sbc1320]

What is the voltage to the HEI?

 

[Calvin_Engineer]

sbc1320, my voltage is reading at approximately 14 volts.

 

[MBZTECH]

Have you checked timing and carb adjustments? RICK

 

[sevenzeronova]

Try a insulator between the carb and intake for less heat transfer.

 

[Calvin_Engineer]

MBZTECH,

I checked the timing on Friday. It didn't tell me much, because it has an aftermarket balancer. So what is 8 degrees on a stock piece, might be 20 degrees on this. I don't know what to do regarding my carb adjustments. This is the first carbuerated car I have owned. What do I do?

sevenzeronova,

Would I pull the carb off to install this insulator?

 

[sevenzeronova]

MBZTECH,

I checked the timing on Friday. It didn't tell me much, because it has an aftermarket balancer. So what is 8 degrees on a stock piece, might be 20 degrees on this. I don't know what to do regarding my carb adjustments. This is the first carbuerated car I have owned. What do I do?

sevenzeronova,

Would I pull the carb off to install this insulator?

Yes for the insulator/phenolic spacer.
Need to find TDC and make sure it corresponds to that mark on the balancer. Where is your timing tab on the engine? 12 o'clock postion 3 o'clock?