Small Carb problem

[Mr. Land Yacht]

when we got some warm weather here in MI a couple weeks ago, Magna decided to act up.
The car died on me in the middle of the rd and did not want to start...I had to put the pedal to the floor to get it to start.

after talking with a buddy of mine and observing the carb that night, it appears that my secondary float is possibly sticking and flooding the carb.
when the car has been sitting for any amount of time, I can see fumes coming from teh secondaries.
especialyl from this thing*see attached*

anyone knwo what I shoudl attempted with this?
I already tapped the fuel bowl on the top with a rubber mallet...not a little baby tap, but not a hard whomp either.

other than this issue, the carb is running very well.

[Mercmarquis]

You running a carb spacer? Usually the fumes indicate that the fuel is boiling out. It could possibly be the opposite of flooding out. If you dont have a spacer I would try a phenolic one just to see. They are cheap too.

If it is indeed flooding out more than likely fuel will come out of the vent and pour all over your motor and down the carb. In that case its unlikely the float is sticking but rather there is dirt in the needle and seat and will require it to be taken apart and cleaned but your be better off replacing the needle and seat. And get a new fuel filter asap. I always have one before the pump as well as a small one right before the carb.

[Mercmarquis]

Oh yea duh, one way to know for sure is pull the sight plugs on the side of the carb, if fuel is gushing out its obviously flooding. If its not then try the spacer and adjust the float to the proper fuel level.

[1987cp]

Eek, not good. Why don't you pull the rear float bowl and see what you find?

[turbo2256b]

The carb has sight plugs from the factory. Fuel level should in most applications on a BG carb be set somewere between the bottom to middle of the site window. Lowering it and raising the level affects the jetting. All BG carbs I have messed with out of thee box are set at the top of the window. Even 12 second cars Ihave tuned dworked best at the bottom portion of the sight glass.

[turbo2256b]

Most carbs will steam a bit after shut off hot. Thats one reason for the carbon canisters were hooked to them to reduce emisssions. If it seems to much a plastic spacer can help. Yes a needdle and seat could be leaking. Some residual pressure in the line might not be sufficet to close the seat properly and some extra fuel coul be leaking it.

Dont know how much its but if steaming as much as is caused by the accellerator pump on a hot engine shut off. Check your float level...if that dosent help try a heat restant spacer. Also look for sources of heat that could transfer into the fuel lines anywere the lines run.

[Mr. Land Yacht]

I just thought of something, reading Pete's post...

you guys know about my coolant issue right?
well, since so much of the coolant leaks out then that would cause teh engine to run much hotter and not cool the intake well.
also, the night it happened, I would pump the throttle with the car off and I could hear boiling as Pete mentioned. I had never heard that before.
As spiradic as this issue is in the weather, the coolant leaking might just be the fix all to it.
That would make total sense if that was the issue.

ps:
I already have a 1" Aluminum spacer.

[turbo2256b]

An aluminum spacer dosent block heat. THE EXTRA GASKET OVER A SET UP WITH OUT A SPACER MIGHT HELP but not much

[Mr. Land Yacht]

allrighty.
I'll get over to home depot tonite and get some teflon paste to fix the coolant leak.
I might even pick up some JB Weld just in case.
it's raiing cats and dogs today....doesnt look like it will stop...so I'll get the stuff and fix it asap.

thanx mangs.

[DuceAnAHalf]

An aluminum spacer dosent block heat. THE EXTRA GASKET OVER A SET UP WITH OUT A SPACER MIGHT HELP but not much

aluminum would make it worse since aluminum conducts heat very very well

[gadget73]

I've never had my EFI system do this. It also doesn't require fiddling with the spacers or floats

[torquelover]

What's up with the coolant leak Colin?

FI FTW

[turbo2256b]

I've never had my EFI system do this. It also doesn't require fiddling with the spacers or floats

I have had EFI cars have serious issues with vapor lock..carbs as well. Have had carbs crap out rebuilt them for 30 bucks. EFI maybe a few sensors for 25 to 120 bucks a piece, or a new ECM or a few solinoids a pip sensor possibly pick up coils in the dizzy melt down. Lets see I have a 1" spacer between my upper and lower intake, oh guess what its made out of heat resitant material. Some have killer heads and need a 30 or 40 % increase in fuel and intake air flow. 19# injectors and a factory intake wont work or a carb guy goes to big or too small with a carb picks a wrong intake. Would rather just hear some help info.

Like the issue with the rear bowl vent possibly smoking more than the front when shut off and still hot. The fuel in the front bowl is always being replaced with new fuel. the bowl in the rear is just sitting there not being used and replaced unless you open the secondarys it just sitting in the bowl absorbing heat. At best when not being opened up a bit vaporizes and a little is replaced. The front is always being replaced with fresh cooler fuel.

[1987cp]

Like the issue with the rear bowl vent possibly smoking more than the front when shut off and still hot. The fuel in the front bowl is always being replaced with new fuel. the bowl in the rear is just sitting there not being used and replaced unless you open the secondarys it just sitting in the bowl absorbing heat. At best when not being opened up a bit vaporizes and a little is replaced. The front is always being replaced with fresh cooler fuel.

I was just reading about that situation with respect to WCFB carbs and their using a four-corner idle system to help avoid just such a contingency. I presume Holleys are normally delivered with only one idle circuit, thus the talk I've read about "converting to four corner idle", or is four-corner idle in a Holley just for race motors that need the extra fuel flow at idle?

[Rob Roy]

I was just reading about that situation with respect to WCFB carbs and their using a four-corner idle system to help avoid just such a contingency. I presume Holleys are normally delivered with only one idle circuit, thus the talk I've read about "converting to four corner idle", or is four-corner idle in a Holley just for race motors that need the extra fuel flow at idle?

The common reason for converting a Holley to a 4-corner idle system is a big camshaft and the resulting low manifold vacuum. In this situation, to get the engine to idle at the proper speed you have to open the primary throttle blades a lot...which exposes the idle transfer slot and prevents you from controlling the air/fuel ratio with the adjustment screws. Also, as you mentioned a lot of race engines have large fuel requirements, enough that with a 2-corner system you could have the adjustment screws backed out all the way and still be lean. A 4-corner setup allows you much more control. You can split the idle air between the primary and secondary blades and evenly distribute the fuel with the 4 adjustment screws. I have a 750 Holley on my Camaro with this setup, it was a huge improvement over the carb with a 2-corner idle.

Some people drill holes in the primary throttle blades to allow extra idle air without opening the blades excessively, this does work but it is mostly trial and error to see what size holes you need...and the carb isn't much good for a mild setup once the holes have been drilled.

As for the Demon carb in the original post, I would remove the secondary bowl and inspect the bowl/needle/seat for foreign material. It is not unheard of to find aluminum shavings or dirt in new carbs. One piece of debris under the needle will cause tons of problems.

What are you running for fuel pressure?