Can anybody solve this hot start issue? I'm out of ideas!

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my5thmopar

my5thmopar

Life Long MOPAR Owner
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I can’t seem to resolve my hot start issue and tired of buying stuff. I know there are a lot of particulars; I’m just trying to be thorough. 72 Dart 318, bore 30 over, stock heads, flat top eyebrow pistons, Comp XE256, New Eddy Performer Intake and New 1406 Carb. Engine was rebuilt 800 miles ago.

Here is what I have done. New water pump and radiator. Ignition Pertronix II and Flamethrower II coil, distributor is new and locked at 20 mechanical. Idle is at 14 btdc, 34 deg at wot and vacuum is at 20. Engine is set to idle at 700 rpm in park. I have new mechanical fuel pump, pressure is regulated at 5lbs, new fuel filter. New Autolite 66. The carb has been cleaned and float, idle mixture adjusted, needle and seat clean and working. Also new Eddy Heat spacer 9266. I have also insulated the fuel line from the pump to the carb. Engine temp gauge is always below half and never dies or gets hot.

I am confident that the carb is getting hot and either boiling fuel or flooding. The bowls are not empty. If I pump the throttle it gets worst. If I hold the key for 5-7 seconds it will start. If I hold the throttle to the floor it starts quicker. The engine starts quick when cold and every time hot but, just takes 5-7 seconds.

Is this normal and do I have to accept this? Can this be fixed or what else can I do? Thicker spacer, Holley, electric fan. I’m all out of ideas. I’m hoping somebody can fix this. Thanks
 
I'm thinking you should try an insulator between the carb and intake.

I found this on the net. Quote: This heat insulator is ideal for preventing fuel percolation in Edelbrock Performer Series carburetors.

USe google and search for "carburetor heat insulator"
 
check your floats..........

got same carb on a eddy rpm manifold in las vegas, never had hot start problems in summer
 
I'd check the float setting also, but a short spacer if your hood will allow it will go a long way to keeping the fuel from precolating. If you don't have the hood clearance, try the thicker gaskets.
 
Put an insulated carb spacer in there, and SERIOUSLY CONSIDER a vapor return system. THEY WORK. Ma installed them in the hemi and 440 sixpack cars from the factory

If you can rework your fuel tank system (vent) and don't need the carbon canister for state smog in your area, you can use the 1/4" fuel line for the return

Get a Wix 33040 (5/16) or 33041 (3/8) which has a 1/4" vapor return port built in. You can mount the filter can either vertically or horizontally so long as the 1/4" fitting is on top. Here's one now:

33041.jpg
 
I think he says he already did the heat shield/spacer... Seems to me if you are needing to floor it, it's flooding, or too rich when you turn the key.
The 1406 is electric choke. What is the choke wired to? When you shut the car off hot, remove the air cleaner and look down the carb... Is the choke fully open? How long does it stay that way? Is there fuel still dripping from the boosters? Have you tried lowering the float level? Fuel will not normally "boil" out of a carb in the sense that it doesn't bubble and splash all over. It will evaporate out the vents but there's not enough pressure in the bowl to force it up into the boosters unless the float level is high to begin with.
 
I had the same issue with mine. The Eddy carb I had would do the same thing. Swapped to a Holley street avenger and problem solved. I messed with that Eddy carb for weeks, bought the calibration kit, did the spacer etc... Finally I got fed up with it. Holley went on and all around better performance and starts right up and idles hot or cold with no choke.
 
Make sure the bowl vent is opening. All of my fuel delivery issues turned out to be the bowl vent not opening.
 
With the edelbrock carburetor on the performer manifolds in the mopar line it is important to have the edelbrock #2732 plate installed. It acts as a heat shield as well, and can be used together with what you have already.

The edelbrock instructions are pretty clear about the 2732 plate, but it somehow gets overlooked a lot.

Of course others here have already covered the float level issues, but too much fuel pressure can cause this too. Even if you set the floats right, too much pressure will push past the needle & overfill the bowls. Since you can't see it, you calibrate & tune with a too high float level - so it runs great but floods on a hot shutdown... Those carbs are just fine with 4 psi, and 7 or 8 will sometimes be too much. They really are a Weber in that way. I had to run a regulator on a mechanical pump.

B.
 
How good is the starter? Your condition reminds me of what was happening to my convertible. After many carb adjustments, I finally bench tested the starter and it was drawing too much amperage under hot conditions. I replaced the starter and the car starts right up when hot.
 
sounds like the fuel bowl is not vented right and forcing fuel into the intake, so you get flooded out. Thats why you have to crack the throttle open.
 
oliver said:
sounds like the fuel bowl is not vented right and forcing fuel into the intake, so you get flooded out. Thats why you have to crack the throttle open.
Click to expand...

Edelbrock 1406 carb is what he said he's running. Those do not HAVE a closeable vent. Unless the vent, which is fairly large, is plugged by insects or mud, it would be pretty diffecult to plug 'em

I think this is a simple matter of HEAT after shutdown, fuel boiling over the top and heat pushing fuel past the needle/ seats.
 
I used to have this problem all the time with the 360 that was in my truck (which is now in the car)

I put a 1" spacer. Problem solved.
So far the girlfriends Duster doesn't have the problem but she's using a Holley..which doesn't heat up as fast and percolate the fuel like and Eddy does.

The insulator gasket works..but if the engine is running nice and toasty under the hood I bet it's not quite enough to stop it.
 
I have been working on this issue and still can’t fix it. I pulled the top of the carb off and looked inside. There was fuel in both bowls. There was also noticeable fuel on the passenger side of the intake floor. I am still thinking the engine is being flooded. If you want to suggest something else or ask a question. Please look through the thread since several items have already be tried. Since last post, I have done the following:

Swapped the .5 inch heat space for a 1 inch phenolic spacer.
Lowered fuel pressure to 4.5 lbs
Cleaned carb again.
Lowered float to .5 inch
Put on a Wix 33040 with vapor return
New starter small for a 97 Dakota

I’m going to Edelbrock Monday and see what they can offer. Probably nothing but, I’ll try anyway. Anybody?
 
Did you check starting spark? Maybe I missed that. Might need a helper.

Remove the coil wire at the coil, use a grounded probe (12V test lamp will work) and hold it near the top of the coil tower. Crank the engine USING THE KEY not by jumpering the relay.

I suppose it's possible the carb casting is cracked, but not very likely.

When you have some time, confirm the following:

Make sure the fuel system becomes UN pressurized on shutdown, IE make sure your return line is clear, no obstructions AND that the tank is not somehow building pressure, so make sure it's vented.

If you can't be sure of this, run a little experiment

Warm the engine up as it would normally show the problem. Shut it down and IMMEDIATELY remove and plug the fuel line at the carb.

Take a quick look down the throats to look for any fuel dripping over into the throats.

Button 'er up just as per normal except the fuel supply unhooked -- you want to retain heat.

Then see if that improves things at all.

You are sure float level is OK?
 
Am i just looking for spark during hot condition?

I inspected the carb when I changed the spacer. I'll do a closer look.

How long to un-pressurize? Checked vent today and it was clear.

I checked the throat right after shut down and saw nothing. I guess I need to stare at it for 15 minutes.

I like your test idea, if the fuel line is off means no pressure.

Tried float at 7/16 and 1/2 from gasket.

Thanks
 
1968FormulaS340 said:
40 year old car that takes 5-7 seconds to start when hot.

Why do you think this is a problem?
Click to expand...

Maybe it isn't a problem. I just thought a completely rebuilt engine less than 1000 miles ago and with practicably everything new. Might just start quicker.
 
DFX 340 Duster said:
How good is the starter? Your condition reminds me of what was happening to my convertible. After many carb adjustments, I finally bench tested the starter and it was drawing too much amperage under hot conditions. I replaced the starter and the car starts right up when hot.
Click to expand...

The electrical side of the coin can make one crazy.
The system is designed to send full battery voltage to the coil during start.
If there is a connection heating up and growing resistance during run ( like the fusible link, etc.. ) The strater could still spin fine while the rest of the car suffers from low voltage.

My 73 once had a might start / might not attitude for a time. Cold or hot start didn't matter. I finally found the problem to be in the controller for a secondary choke heater . Pulled the hot wire off that sucker, problem solved.
 
my5thmopar said:
Am i just looking for spark during hot condition?
Thanks
Click to expand...

YES, and you are looking for a number of reasons. First to be sure the ballast resistor bypass circuit (in the switch) is working, to make sure that the coil or ECU is not laying down when heated, and that it simply does have a nice fat spark.

And, I guess in the back of my mind, what was posted about starter draw. IF the engine tried to "drag" when hot, or if the starter is laying down when hot, this will pull battery voltage down when cranking hot. You might crank it when real hot and measure battery voltage. Should be a MINIMUM of 10.5 or more. Would not hurt to check at the coil positive terminal as well, should be very close to battery cranking voltage.

Below 10.5 means you don't have enough battery, cables too small, starter is overcurrent, or engine has a drag problem.

my5thmopar said:
How long to un-pressurize? Checked vent today and it was clear.

I checked the throat right after shut down and saw nothing. I guess I need to stare at it for 15 minutes.
Click to expand...

Should depressurize in seconds. If there's anything there after 10 seconds, I'd look for some problem, like severe fuel boiling in the supply line acting as a "boiler" or a restriction in the return

So far as "down the throat" you might let it sit HOT for about 1 minute, then look down. You should see "we" in the throats and on top of the butterflies if it's boiling over in there.
 
67Dart273 OK 2 things to add if it changes your suggestions. One I have a Pertronix II and Flame thrower so the ballast is bypassed. Starter is new. I'll complete the tasks and report back. Thanks again for the help.
 
For anyone that searched and found this thread. I haven't been able to resolve the issue. I followed all the suggestions and have checked everything noted. Maybe you will have better success than I did. My solution is to crack the throttle slightly open and it starts. I also have idle set at 850 rpm which seems to help. I'm going to accept it as it is. Thanks to all with the help.

Craig
 
1968FormulaS340 said:
40 year old car that takes 5-7 seconds to start when hot.

Why do you think this is a problem?
Click to expand...

My guess is because he's comparing it to cars 40 years newer that start in an instant no matter the temperature. lol
 
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