hard start hot and white vapor out top of eddy #1904

[kelly76]

Hi, this is my first post but I've searched for hours looking for a solution. I recently kit'd an Edelbrock #1904 quadrajet with Cliff's standard kit. From what I could tell (and I'm no pro on the internals of the quadrajet yet but getting closer), the carb is all stock along with the 73 jets and the rods. I put this on a 250 hp 350, stock engine and performer intake. It fires right up cold and runs awesome down the road, at WOT, etc..  However, when I shut it off, anytime from 45 seconds to 30 minutes after shutdown, it is very hard to start when hot. I can pump the throttle and fuel squirts out but eventually have to hold throttle wide open and crank for 15-30 seconds or so.

Upon shutdown when hot, I can pull air cleaner and see a white vapor pouring out of the primaries. What is this a sign of?  Sorry for the long story.

Float is set at 3/8" according to edelbrock information. Choke is staying open when hot and cranking. Timing is at 14 base and 34 total. Car idles great and throttle is very responsive while running. Fuel pressure is unknown at this time but a regulator/gauge should be here Tuesday. I'm thinking with the stock mech fuel pump I'm running a bit high. It is rated at 7-9 psi.

This setup is in a '64 rambler American so the engine bay is tight and things are hot. Would a spacer under the carb help or insulating the fuel line?  Thanks for all your help.

[Zac Agee]

I'd listen for any gurgling sounds that will let you know if its boiling fuel can happen befor and after the fuel pump specially with headers. If its boiling can fix by insulating lines or running a return if possible

[kelly76]

I tried that a few times over the last several days. Can't hear anything, just see the white 'smoke' that comes out of a passage in the primaries. No headers, just exhaust manifolds, but the engine bay is small and gets hot in there. I did try to insulate the lines with what I had laying around (funds depleted for now).  I used 1/2" copper pipe foam insulation wrapped in hvac foil tape.  After driving for 5 miles today (95+degrees), I popped the hood and couldn't hold onto the first 6" of fuel line coming out of the carb for more than couple seconds.

I'm guessing heat is my enemy here.  I'm gonna open up the shroud some more (I think it's not allowing enough air past it during hwy use as the car gets a tad warm on the hwy  or remove it completely and go with dual electric fans.

As always, thanks everyone for their suggestions and please keep them coming.

[kelly76]

Well, I installed a pressure regulator. Have set it anywhere from 4.5 to 6 psi and still have same issue. I then installed 1" phenolic spacer.....still have same issue. Idles great, drives down road great, runs great at wot. Upon shutdown, white vapors, fuel dripping on primaries and hard start.

Anyone have any suggestions?

[kelly76]

Ok. Last attempt to resolve before swapping on my Holley. Please if anyone has any suggestions I'm all ears. Today I spent a lot of time setting the float at different levels. 1/4, 5/16, 3/8, and 11/32". Same result each time. I did find out that on a cold engine, if I fire it up, run it for about 3 min and shut it down I will still get the white vapors with fuel dribbling onto primaries and leaking out throttle shaft.

[von]

My guess is either a bad float, bad needle and seat or a leak between the seat and carb body. A common mistake is accidentally leaving an old seat gasket in place when installing a new one. Also sometimes the seat gasket surface of the carb body gets damaged or eroded.

[kelly76]

Thanks Von. When I pulled carb yesterday! I inverted it and pulled vacuum on fuel inlet and the needle/seat held tight.  The float was in the kit I got from cliff but it could be bad I suppose.

I checked for the seal before I screwed in the seat but I could have missed it. Would the needle/seat hold a steady vacuum if the old seal was still in place?

[kelly76]

Also! How do I check the float? It's the black float that came in cliff's kit. Do I just drop it in a container of fuel and make sure it floats?

[SundanceKid]

Are the well plugs leaking?

[kelly76]

Pretty sure they aren't.. I tested them according to cliff's book with soapy water and air pressure. I can now start the car, run it for 20 seconds when cold, shut it off and immediately look down carb and see fuel dripping heavily on the primaries. Feels like float is too high. Not sure how low I can adjust it and be okay.

[von]

If the needle and seat hold vacuum for an extended time then them and the gasket area are probably good. If the float is new then it's likely good too. Are you using the little clip that ties the needle and float together? Those are often installed wrong and can cause problems. Many people including me leave them out entirely. I think Cliff does too.

[Shark Racer]

The clip is a good thing to check - if it's installed wrong it can leave the needle not well seated in the seat.

It should be around the half-cicrcle part of the float, toward the float well, NOT in either of the holes. Those holes were added to trick us.

One of these days I'll get a better photo, but you can kind of make it out here: