Hard starting when the engine is warm

Hi everyone,I'm a new member and I need help.I bought a 1978 correct craft mustang17 off this website and I love the boat, but I have a nagging problem. The engine is a stock 302 an this is what I have done to it. This spring I installed a new 600cfm edelbrock carb on it,set the fuel mixture and is running perfect.I also installed a pointless system with a new electronic coil.The ballest resistor is taken out of the system for it all to work correctly.All new plugs,wires,cap,and rotor have been replaced. When the engine is cold it starts perfect,warms up to proper temp and runs perfect.When I shut the engine off I can start it right back up.My problem is when I let it sit for 5 to 10 minutes It takes for ever to start back up.Like 8 to 10 cranks.As the day goes on it gets harder to start.I'll have to crank the engine 3 times,each time 8 to 10 revolutions before it starts and on the third time I have to bury the throttle to get her to start.I have checked everything an i am stumped.At first I thought I was boiling the gas out of the fuel bowls of the carb because of heat.Thats not the case,I can pull the thottle back and I have gas.I check the anti-siphon devise at the tank and it is working.The engine is perfectly time at 10 degrees btc and I have good vacuum on the engine, it 18 inches.The plugs are burning clean. So I have gas and fire but its just hard starting when the engine is warm.When it does start it runs incredible.Need some help guys,PLEASE!

She's flooding out due to a leaky needle valve (or two). Time for a carb rebuild.

David F wrote: She's flooding out due to a leaky needle valve (or two). Time for a carb rebuild.

I guess you missed the part about it BEING NEW?

Tim D wrote: Check the exhaust manifolds and make sure you don't have water leaking in past.

That would cause a hydro-lock situation and prevent it from cranking, while it bent rods because it couldn't compress the water in the cylinder.

It does have the electric choke but I never touch it or adjusted out of the box I thought that was done at the factory.I'm a little ignorant when comes to carbs.Thanks for the tips and if you can think of anything else let me know.About the hydro-lock situation,I don't think thats the problem because it will turn over. This engine only has 214 hours on it an its the orginal,just to let you guys know.

I would have to say you are wrong about the leaking exhaust. Mine did this once. It ran fine, the exhaust was blow the water out while it was running. But when you turned it off, water could enter through the exhaust port, which would slow cranking some, and hindered it from starting a few moments after turning it off. The longer it sat after turning it off the quicker/better it would restart.

    I always liked to run my choke a bit on the lean side and have found better results pumping the throttle a extra time in real cold weather.
     When it does eventually start, does it pour out the black smoke?? If so, chasing a ignition problem wouldnt cure it. Good luck!!

                                  Jeff...

79,One question if I turn the choke 2 notches rich wouldn't I put more gas to it.Seems to me that I would want to lean it out 2 notches.I have noticed that my choke does seem to start closing to soon after I shut it off.Is my thinking correct about this or am I wrong?

Adjusting the choke doesn't really add any more or less fuel it adjusts the amount of air allowed to pass past the top butterfly. Basicly the coil is a spring tension for the top butterfly and the choke pull-off is what cracks the butterfly once started so it's not completely closed. As you rotate the choke stat you should see the top butterfly move some. The elect. connects heats up the coil and opens the top butterfly all of the way once it's hot and you can adjust the choke stat hot or cold engine running or not.

Try 2 notches rich and go from there, just make sure the choke pull-off is set corectly, so you'll have to re-move the arrestor to check. Actually check the choke pull-off setting first.

More info:

An area of the carburetor generally misunderstood is the function of the automatic choke. Automatic chokes use a bimetallic coil to close the choke plate, and vacuum to open the choke plate. It is important to understand that the bimetallic coil does NOT open the choke. Automatic chokes are of two types: integral, and divorced (also called remote). The integral choke is an integral part of the carburetor. The divorced choke resides on the manifold (divorced or remote from the carburetor) and has an operating rod from the choke to the carburetor. In general, carburetors with divorced chokes use a separate choke-pulloff to open the choke. Integral chokes have a piston inside the choke housing. In general, the bimetallic coil rotates when cold to close the choke. As the bimetallic coil is heated, it relaxes, and the choke is pulled open by vacuum. In the case of the integral choke, there will be a tiny vacuum passage from the throttle area (vacuum source) up to the choke housing where vacuum is exerted on the piston. If this tiny passageway is clogged (often), no vacuum is applied to the piston, and the choke does not fully open. A problem with divorced chokes is the use of an incorrect thickness carburetor to manifold gasket when the carburetor is rebuilt. This will change the required length of the choke operating rod, and may result in the choke either not closing, or not fully opening.



Setting an automatic choke is quite simple, even if an aftermarket choke is used. For integral chokes, loosen the retaining screws such that the choke will rotate freely. Adjust the choke such that the choke plate just touches closed at 68 degrees F. (65~70 degrees is close enough). Tighten the retaining screws. For the divorced choke, the same setting applies, but bend the operating rod to set the choke plate.

Hey guys,last night this what I did. When I first started I looked at where the choke was and it was already set 2 notches to the rich side right out of the box.Then I rechecked everything,timing,vacuum readings.Found out due to a bad gauge that my vacuum was low so I recalibrated the carb.I reset the idle mixture screws and got 18 inches and the boat did sound better.I also noticed the butterfly would not completely open so I actually had to lean the choke open to the first rich setting.I did notice once I did this that the choke would stay open much longer when I shut the engine off. .The engine seem to start a little better,like the sixth crank .Also each time I started the engine I would never give it any thottle to start when it was warm.If I set it any richer it would just crank and crank so I set it back to the first rich setting.I really don't think I've really fixed my problem.Now To let you know I can simulate my problem whether the boat is on the trailer,with a hose hooked to it or in the water.I know 0n my 1965 mustang car that I own it has the old autolite carb on it with the stove pipe setup for the choke and it works great.Once its warm all I have to do is hit the key and it starts right.So tell me guys what else could I be missing or is this the best I'm going to get.Maybe I'm just to picking on how it should be starting,but I don't think I am.Anymore suggestions would be great.

I turned the mixture screws in until they seated,backed them out two turns then adjusted each screw in to lean it out and got 18 inches of vacuum.

A old mechanic kinda showed me how to do it,but I went onto a website for ford motorsports and they showed how to calibrate a edelbrock performer series like I have on a 302 by using a vacuum gauge instead of a o2 monitor.So I just went by that,its what I had to go on.Anymore suggestions from anyone would be greatly appreciatied.Thanks to 79 for your input also.

I'll give it a try JoeinNy.I just did what 79 said.When i started the choke was already 2 notches to the rich side of the choke,the butterfly was still not open all the way when the engine warmed up .So I took it to the first notch,this opened the butterfly all the way and when I shut the engine off it stayed open longer.Like I said it may start a little better but not like I think it should.

bmiller,

regarding the fuel mixture adjustment,

the holley manual supports your old mechanic in that they say to gently seat both screws, turn out 1-1/2 turns, start the engine, let it run up to temperture, turn each screw in use 1/4 turns till rpm drops, then use 1/4 out turns till rpm drops due to rich mixture, now set each screw to to somewhere between the two extremes where maximum rpm and maximum smoothness is obtained obtained.

although this is a subtle difference in all the approachs suggested, i since that it's going to be a subtle change your looking for. nonetheless, set it according to manufactures procedures, and you can atleast move on to further analysis other than the fuel mixture.

Now set your idle speed adjustment till specified RPM is acheived