Little carb issue

[DPete]

I have a 350 with Edlebrock carb (manual choke) and intake. Starts cold and runs fine but when I shut it off hot and try to start it up after several minutes the engine is hard to start and seems flooded. I took it to the local dyno tune shop and they made some changes but the condition still exists. Anybody have a clue? The dyno shop checked spark and say it is good. It will start right up if shut off hot and immediately restarted, the problem is when it sits, say long enough to have lunch. I asked about the float level, they said it's good.

[1project2many]

It's possible your engine really is flooded. If so, the question is why?

Some suggestions, in no particular order:

1) Fuel leaking from the bowl into the engine after the engine is shut off?
2) Float level adjustment allowing fuel vapor to fill the intake while the engine heat soaks?
3) High fuel volatility combined with engine temperature causing fuel vapor to fill the intake?
4) Saturated float failing to close needle valve?
5) Contamination in the needle valve preventing valve from closing?

This can be quite a fight to cure in some cases. Checking float level and potential leaks are the first step. Checking the float for saturation or replacing it is fairly easy. At the same time the bowl and needle can be checked for foreign materials. If the problem is due to modern fuel and carb heating you may be able to help it with a phenolic spacer between engine and carb. Or, you may want to learn to do what many old-timers can do and start the engine with the throttle in "Clear Flood" mode, which means pedal to the floor. As soon as the engine begins to catch you let the pedal up and the truck will start without revving up excessively. Some of us have so much practice you can barely tell the engine is flooded.

[DPete]

Thanks for the good advice, I'll get it somehow

[Jesse Z]

Clogged fuel tank vent. Clear vent obstruction.

Heat soak. Install phenolic spacer below carb for insulation. Insulate fuel lines that pass near exhaust.

[DPete]

How thick of a spacer? 1"? It's an aluminum intake manifold

[Jemezcrusher]

Originally Posted by jesse z

clogged fuel tank vent. Clear vent obstruction.

Heat soak. Install phenolic spacer below carb for insulation. Insulate fuel lines that pass near exhaust.

x2

[bosco]

When it's hard to start, does the engine turn over like it's tight? Mine did this and I had too much timing in it. Pulled a bit of timing out and it starts great when hot. I have the same set up.

[nail pounder]

Originally Posted by DPete

How thick of a spacer? 1"? It's an aluminum intake manifold

With aluminum intake I believe you need a spacer. I had the same issue, and boiling fuel on a hot day. Installed this and it's been fine ever since.

[gbooth]

Back in days gone by I had a truck with a 327 in it and a holley carb. It kinda did the same thing started great cold but when warm after sitting for a few minutes acted like it was flooded. I found that my low profile air cleanner, the lid presed down the vent tube on the carb causing it to boil over and flood the engine. Removed the tube and problum went away.

[dsraven]

get it hot, pull the air filter, shut it off and check if fuel runs out the vent into the throttle bores. if it does then look at the inlet needle and seat, fuel pressure setting etc. if not then let it sit for an hour or so and then open the throttle slowly so as not to spray fuel all over from the accel pump, then look past the open throttle plates into the intake and see if there is raw fuel down there. if so check for the reason why.
I have used the phenolic heat gaskets as well and also had one car with that plus an alum plate under the carb that was larger than the carb base so it sort of deflected any heat waves out and past the carb. could be fuel boiling issue causing fuel to run out the vent into the throttle bore area. you could also try placing a short piece of clear tubing over the vent tube that goes vertical (on a hot engine with the air filter off) and see if fuel rises in the tube, meaning the fuel is actually boiling and escaping through the tube and would have gone into the throat of the carb if not up the tube. that escaping fuel would be your flooding issue. fix the heat soaking issue to fix that issue.

[DPete]

Originally Posted by bosco

When it's hard to start, does the engine turn over like it's tight? Mine did this and I had too much timing in it. Pulled a bit of timing out and it starts great when hot. I have the same set up.

No it turns over fine, the advance checks out good. I'm going to order a spacer like the other posts suggest. Thanks for the replies, will keep you posted on spacer results

[DPete]

Bought the spacer in the above pic, double checked the float level while I had the carb off and installed spacer. Seems to have cured it, will know for sure as time goes on. Thanks to those who posted.

[dsraven]

no pic, didn't happen. haha
good to hear you cured it.