Hard to start help

[American Mister's 2002]

So I have a 1976 square tail 

current set up is: 

38/38 Weber 

292 cam 

fresh plugs, rotor, cap. 
stock exhaust 

electric fuel pump 3.5psi no regulator 

otherwise mostly stock 

my current issue is that after the car sits for any period longer than 30 minutes it’s start or restart is very laborious. Once started and warm it runs wonderful. This began after installing the bigger cam. 
 

I have also adjusted choke settings and dialed in lean idle settings. 
 

Any tips appreciated! 

[John76]

Do you have a fuel return circuit connected to your electric pump?

This will circulate (cool) the fuel in the lines to help prevent vapor lock. It will also allow you to lower your fuel pressure a bit depending on the return line orifice size.

The Ethanol in fuel starts to boil at 178 degrees F.  When your car sits (with the hood closed) after a drive, the carb can easily reach 185 degrees F which causes percolation and vapor lock.

 

Solutions:

- Fuel return line to keep fuel cool. Run electric pump for a few seconds before starting.

- Phenolic block between the carb and intake manifold.

- Reflective heat shield (aluminum duct tape) under float bowl and air cleaner. 

- Keep fuel lines and filters away from heat sources (head, coolant lines, etc.).

- Fresh, cool air to carb from outside the engine bay.

- Check condition of all fuel lines. No air leaks!

- Try to use "real" gas ... no Ethanol! (If you can find it).

 

John

 

[American Mister's 2002]

Thanks for this info! 

 

Do you think it could be vapor lock even though its hard to start when the motor is cold and been sitting inside the garage? 

 

Thanks

[Son of Marty]

Your electric fuel pump should eliminate most vapor lock problems, when you go to start it  how many times do you pump the gas?
 

[American Mister's 2002]

Typically the more I pump the harder it is to start. I started with 3-5 pumps then tried 7 and now only 2. Best results are 1-2 pumps. If pump it too much its definitely flooding and having a real hard time starting. 

 

Is this a plug gap issue? I thought I was gapped to just under .30 so around .28 or so... 

[Mike Self]

With an automatic choke, at least in theory, a single pump of the accelerator pedal (when cold) should be enough to "set" the choke--i.e. close the choke flaps and position the fast idle.  To see if that is happening with a single pump, on a cold engine, pull the air cleaner top and floor the accelerator once.  If it sets, that's all you need to do, because every pump of the pedal squirts more fuel into that cold manifold via the accelerator pump, and all that gas is gonna flood the engine.  

 

With my manual choke, I've learned that when cold, I pull the cable all the way out to set the choke, and hit the starter without touching the accelerator pedal.  And it starts right away.  

 

mike

[American Mister's 2002]

I have verified that the choke is engaging when the accelerator pedal is pushed once. However, with the choke engaged its worse if no choke engaged. So I have to a very low setting of tension. (Florida) Climate.