bwiencek

Hello all,

I've got a built 355 (5.7) that I'm using a 750 CFM edelbrock marine carb on. The engine runs great, but I've got a problem starting after stopped for a few minutes. The engine just cranks over and over for about 45 seconds before stumbling to life. I've tried the following things and have exhausted all the possibilities that I know of and the edelbrock techs know of. This is a BRAND NEW carb, not a re-man or used one so I've sort of eliminated problems with an old carb.

- Adjusted idle mixture (several times, following instructions, with a vacuum guage and other various ways)
- Installed fuel pressure regulator, set to 4 PSI
- lowered float level 1/8"
- checked for vacuum leaks at carb base, intake manifold, etc. (Used propane, carb cleaner, WD-40)
- tried a little faster idle and a little slower idle RPM.
- Ran premium gas, ran cheap gas
- checked ignition system, replaced plugs,wires, cap, rotor.

The engine idles great, runs great, has excellent power, and generally behaves fine. It's only when stopping for a couple of minutes then trying to re-start that the engine has a hard time starting. If I "blip" the throttle before shutting down it seems to be better on the restart.

Any ideas are greatly appreciated!

- Brian

MKast

May I ask what your "hot" engine starting tecnique is?
Is the choke still attached, or milled off? Is it slamming shut?
When you crank the engine, does any cylinder sputter?

John B

It may be a condition known as heat soak, where heat from the intake manifold transferes to the carburetor base and boils the fuel out of the fuel bowl. If the fuel goes into the intake you will have a flooded condition. The fix is to make sure you have a proper carb to intake insulator ( gasket ). It should be 1/4 to 3/8 in. thick. Some times multiple gaskets will help.

Good luck JB

bwiencek

Mkast - the choke is factory stock, electric, and it's verified to be open at the time. The starting procedure WARM is to simply turn the key and it should start.

John B - The Carb is barely warm to the touch - I'm guessing no more than 110 degrees - no problem keeping a hand on it for an extended period of time. Plus have run it with the hatch off. Also according to the Edelbrock techs lowering the float level should have cured that if it was the case (boiling over) I've yet to try their 1" spacer, but it was low on my list once I felt how cool the carb was. Plus this also happened when tuning it in october and 50 degree temps outside where the carb barely got warm.

excaleagle42

hello
i would install a carb spacer or extra thick gasket regardless, take off the regulator or at least raise the pressure to 6 to 6.5 lbs. the edelbrock carbs have two sets of needls, seats, and floats unlike a quadrajet and your stock fuel pump won't overcome them unless your over 8 lbs.
put your floats back to the recommended settings. my guess to what is happening is, when you shut your engine off, the coil for your electric choke cools off and closes again even though your engine is still warm. it doesn't take very long. when you go to restart, your too rich.

bwiencek

excaleagle42 - Thanks for the reply - the regulator is on it for a reason - according to edelbrock they want to see 5 PSI max and they thought that it might be fuel was being forced past the needle/seat so that's when the regulator was added - I've removed it and added it back in-line several times with no change. The fuel pressure with the regulator is rock steady through WOT.

The choke is fully open when re-starting - that's verified by having the spark arrestor off and looking at the carb while others start the engine - I've checked that one every time that I've been back there fooling with the thing! I'll be trying the spacer probably next weekend.

excaleagle42

if the spacer doesn't work, i would try another coil. make sure its not sitting flat on the intake collecting heat also.

Gary Anderson

Is there fuel in the carb? Try pumping the throttle a few times and see if the pump jets spray. If not it's boiling out or you've got a siphoning problem (all the fuel is returning to the tank).
Fuel lines getting hot, maybe vapor lock from rerouting the line for the new carb. Try insulating them.
Do you have spark when it's cranking? Try a new coil, they're cheap. It may be getting weak when hot.
My $0.02
Gary

bwiencek

There is fuel in the carb - accelerator pump shoots a healthy shot when throttle is opened and engine warm and not running. Fuel pressure holds at 3.5-4 PSI the whole time that the engine is OFF which leads me to believe that it's not draining back and it's not going into the bowl.

Coil is in the stock location, it's a more recent one (about 25 hours on it before engine work) - it was replaced when doing some testing for a miss which turned out to be burnt valves.

I'll test the coil and throw the old one back on just in case.

Thanks for all the ideas guys!

FlyFast

What type of intake are you running? My rebuilt 355 vortec heads edelbrock 600 cfm carb did not like a stock qjet intake with the adapter. The same motor with the edelbrock air gap for vortec heads works great. the intake made a big difference.

Good luck