Edelbrock 600 carbs and loading up when hot...what is the REAL fix???

[AKcharger]

A google search shows these Edelbrock carbs have the save problem...they all seem to load up when hot then not what to start. Both my Cars have them and both suffer from the same problems. A phenolic spacer helps but I've just leaned to live with it, but I want to fix it.

- Carbs run good...when cold so I don't want to trash them if I don't have to but I see all these "supposed fixes" out there...Change metering springs, test and re-set float levels, run a fuel pressure meter looks like it's just doing some serious work and hoping something fixes it! So question is...Is there really a fix to this?

- If not what is a good suggested replacement? Seems like a lot of people are happy with Demon carbs

[myk]

So you're having starting problems only, or driveability issues as well?  For starting the only way my car got over that was when I installed an electric fuel pump.   I'm guessing the electric fuel pump forces fuel past the boiling fuel in the bowls of the carb.  I also have a phenolic spacer like you...

[firefighter3931]

The problem with the Eddy/Carter style carbs is the design which promotes vapor lock. The issue is the location of the fuel bowls which are housed in the main body of the carb. This promotes fuel boiling due to conductive heat.

A Holley style 4150/4160 has the fuel bowls hung on each end of the main body which helps keep the fuel cooler. It's a better design.

Todays fuels are a pain in the azz for carbureted engines. The fuel is formulated for high pressure fuel injection and when it's introduced into a low pressure carbureted application the fuel just boils and causes vapor lock. 


Ron

[AKcharger]

Todays fuels are a pain in the azz for carbureted engines. The fuel is formulated for high pressure fuel injection and when it's introduced into a low pressure carbureted application the fuel just boils and causes vapor lock. 
Ron

Hmm, the subject of fuel came up as well. as I recall the spacer fixed the problem when I put  them on in '03/'05 but it slowly came back...pretty much as ethanol came on-line.

MYK - they drive OK but when hot and in traffic each seems like they want to die and when you do shut it off after being hot you have to treat it like a flooded engine to start it again. now surprisingly all the posts and edelbrock tech page said too high of fuel pressure would cause this problem by pushing fuel past the metering rods...but high fuel pressure is fixed yours? 

[myk]

My electric fuel pump is putting out 5# of pressure or less; I think that's the equivalent of a mechanical pump.  Besides, my Edelbrock 1411 won't take more than 5 or 6#, according to Edelbrock anyway.  I'm not saying that the hard-start problem is completely gone, rather it takes maybe an extra second for the car to fire on a hot start.  With my mechanical pump it took a few seconds and when the engine finally fired you could tell it wasn't happy. 

Doesn't a mechanical fuel pump output change with engine speed?  Maybe the fuel pressure/output of the mechanical pump at startup and idle isn't enough to overcome the boiling fuel?  I'm guessing with the electric pump the fuel pressure and output is constant and there, whether the engine is hot or not, and maybe that's why my hot starts are easier.  Someone correct me if I'm wrong...

[AKcharger]

... with the electric pump the fuel pressure and output is constant and there, whether the engine is hot or not, and maybe that's why my hot starts are easier.  Someone correct me if I'm wrong...

Well wait, if pressure isn't high sounds like the Elect. pump may be putting out VOLUME needed...that would make sense

[AKcharger]

I called Edelbrock, they said chek floats and if they are set to 7/16 change to 1/2 inch...we'll give that a try

[Tom68]

What also can happen is the fuel in the bowls boils and ends up bubbling up out the vents and into the carb body thus flooding it.

I had the same issue on 68 Mustang and eventually went to a Holley which solved the problem

[AKcharger]

What also can happen is the fuel in the bowls boils and ends up bubbling up out the vents and into the carb body thus flooding it.

I had the same issue on 68 Mustang and eventually went to a Holley which solved the problem

Makes sense but there HAS to be a fix! well Started digging into it, no smoking gun yet I guess I'll try setting the floats to 1/2 ?? 

[myk]

Outside of the float level I don't see what else you could try.  Except get a Holley lol...

[firefighter3931]

What also can happen is the fuel in the bowls boils and ends up bubbling up out the vents and into the carb body thus flooding it.

I had the same issue on 68 Mustang and eventually went to a Holley which solved the problem

Makes sense but there HAS to be a fix! well Started digging into it, no smoking gun yet I guess I'll try setting the floats to 1/2 ?? 

Bill,

A couple of things that may help :

(1) install the Felpro 1214 intake gasket (383) that blocks off the heat crossover....this will reduce the intake manifold temp

(2) insulate the fuel line between the pump and carburetor with the DEI insulating conduit

(3) run a return style fuel system to keep the fuel circulating


Ron

[69wannabe]

Like Ron suggest's, block the heat crossovers with the fel pro performance intake gasket. Are you running a cast iron or aluminum intake? Don't know how good a cast iron intake will do in the winter months with the heat crossovers blocked. I have drilled a few holes in one side of the gasket where it is blocked and left the other side blocked so it could get some heat but not circulate the heat and get so hot under the carb. Wrapping that metal fuel line will help, I actually wound up running my fuel line over to the inner fender on the passenger side and mounting my filter there and running it to the carb from there and keeping the fuel line away from the engine as much as possible has helped mine alot even tho I am running a holley carb mine still has had these same issues. If you plan to block the crossovers completely check into a place called cool carb tecnology's. They make several different spacers for different style carbs like eddy's and holley carbs and I have one on my car and they do help with this issue. If you choose to go with the cool carb tech spacer kit you will have to block the crossovers or it will melt the insulation that is in the spacers from excessive heat.

The edelbrock's are completely aluminum which make's them heat up more than the old casting holley carbs. With today's fuel we are all battling these same fuel issues with carbs no matter what brand you have. I have ran several 600 eddy carbs and had good luck with them. Tried a few 750 eddys with no luck so anything over a 600 cfm I go with the holley style carbs.

[AKcharger]

OK, I got it all back together after setting the floats to 1/2 inch and took it out for a spin. It ran fine but it was early evening and wasn't that hot out, I really don't think it did anything

Hi Ron! I was hoping you'd stop by! I read your post and noted that intake manifold gasket, That's next on the list.

- DEI insulating conduit, check

- can you elaborate more on this "return fuel system??"

[AKcharger]

Like Ron suggest's, block the heat crossovers with the fel pro performance intake gasket. Are you running a cast iron or aluminum intake? Don't know how good a cast iron intake will do in the winter months with the heat crossovers blocked. I have drilled a few holes in one side of the gasket where it is blocked and left the other side blocked so it could get some heat but not circulate the heat and get so hot under the carb. Wrapping that metal fuel line will help, I actually wound up running my fuel line over to the inner fender on the passenger side and mounting my filter there and running it to the carb from there and keeping the fuel line away from the engine as much as possible has helped mine alot even tho I am running a holley carb mine still has had these same issues. If you plan to block the crossovers completely check into a place called cool carb tecnology's. They make several different spacers for different style carbs like eddy's and holley carbs and I have one on my car and they do help with this issue. If you choose to go with the cool carb tech spacer kit you will have to block the crossovers or it will melt the insulation that is in the spacers from excessive heat.

The edelbrock's are completely aluminum which make's them heat up more than the old casting holley carbs. With today's fuel we are all battling these same fuel issues with carbs no matter what brand you have. I have ran several 600 eddy carbs and had good luck with them. Tried a few 750 eddys with no luck so anything over a 600 cfm I go with the holley style carbs.

Hi Wannabe! I saw 303 used that cool carb thing on RON sticky thead and had good luck. if the easy fixes don't work I'll just keep throwing $$$ at it till I get it right 

[firefighter3931]

- can you elaborate more on this "return fuel system??"

The 440 engines came from the factory with a fuel vapor separator which had a return line coming off of it and circulated unused fuel/vapours back to the gas tank.

There is an inline filter available from Napa auto that has the return nipple built in so you can set up a return to the gas tank. Dan (Mopar303) has one on his car and it has been working fine. Hit him up for the part number 



Ron

[AKcharger]

- can you elaborate more on this "return fuel system??"

The 440 engines came from the factory with a fuel vapor separator which had a return line coming off of it and circulated unused fuel/vapours back to the gas tank.

There is an inline filter available from Napa auto that has the return nipple built in so you can set up a return to the gas tank. Dan (Mopar303) has one on his car and it has been working fine. Hit him up for the part number 

That seems like a lot of work to replumb all that stuff back to the fuel tank...one a scale of 1-10 (10 not a big deal) how important is that?


Ron

[myk]

Can't rate how important the return system is but I assumed you had one installed.  I have one and I think it helps to some degree...

[AKcharger]

Can't rate how important the return system is but I assumed you had one installed.  I have one and I think it helps to some degree...

My car had the CA emissions package and I think part of the return line is there somewhere 

[histoy]

Adding a return line to the tank would probably help as noted above, but the cars that had one from the factory had an extra nipple on the gas tank sending unit for the recovery hose attachment.  You might be able to add a Tee at one of the tank vent hoses to get the return gas back into the tank.

Last year I had the same problem you described with my '64 Corvette with an AFB carb.   Mine was so bad that it was puking gas out of the carb at the throttle shaft and the gas would then puddle on the intake manifold.  The Vette already had a phenolic spacer from the factory.  I started by blocking the heat going under the carb, but that didn't help.    I lowered the float setting, but that didn't eliminate the problem.  I than added a fuel pressure regulator.  I knew from my Mopar big blocks that 4 1/2 lbs. worked well with my cars, and caused no percolation when hot.  I started there with the Vette, but the problem persisted.  I started lowering the fuel pressure in 1/2 lb. increments, and when I got to 3 lbs. the percolation problem when hot stopped completely.  That's where I'm still running the pressure at today.  I've never had a fuel starvation problem at 3 psi with my 327 engine.  Thought that I'd just toss that out there for your consideration.

[AKcharger]

hmmm good tip, thanks history! 

[b5blue]

I used the heat blocked intake gasket. Tried the 1/8th hole drilled to allow some heat to intake. The hole allowed entire block off to burn away in a few years. Florida you don't need the holes anyway. Here is the return system, with this return/heat blocked/thermal-spacer combo I've no problems.
http://www.dodgecharger.com/forum/index.php/topic,40106.0.html

[Dino]

I had the 750 version of that carb with the same issues. The spacer helped a bit but the valley pan with blocked crossover did the trick.   
I later ran a vapor separator with a return line and although it never hurts to have it didn't change anything. The car ran a lot better on the thermoquad though. I ran a 650 for a short while after that and it was pretty good.

[AKcharger]

B5 and Dino...thanks!

OK I'm gonna do the Valley pan and see where that gets me, stby! 

[myk]

Your crossover isn't blocked off?

[AKcharger]

 :scratchchin:I don't think so, I put the engine together in '03 and don't recall any special gaskets