[belky]

Hi guys, just following on a previous post I put on regarding engine bay temp. Sill having trouble on tick over, I’ve done everting possible to eliminate the heat issues, re routed fuel lines, moved all electronics, 1/2” spacer under carb, that’s all I can fit under the hood,
I’ve managed to improve tick over to 20-25 minuets until it cuts out, what is the operating temp of a carb?. Had a laser heat gun on the carb & is about 150f-155f, poured some fuel into the float & instantly started to bubble & hiss then evaporate, any ideas how to overcome this.
cheers Mark.

 

[SWPruett]

In my experience with Edelbrock carbs, there are a few critical things that can't be sidestepped regarding temperature sensitivity performance. First, you absolutely MUST run a thermal spacer below the carb of at least 1/2", and phenolic seems to be the preferable material over the long haul. Summit Racing has an excellent selection of phenolic spacers for very reasonable cost.
Secondly, pay VERY close attention to the fuel/float level setting. The bowls on the Edelbrock carbs are notoriously small in volume and there is very little room for variation tolerance when heat is a factor. Be sure to set float level to the float body and not the float joint seem or you will inadvertently set the float too low.

You will find that they want to crank a bit long on very hot days even on their best behavior due to the percentage of fuel boiling off in heat soak. However, an electric fuel pump can do wonders for hot restart and start after prolonged storage by quickly filling the bowls without the need to crank the engine.

Hope this helps!

 

[myfirstcar66]

This is part of the reason I shelved my Eddy1406 and bolted on an Autolite 4100.

 

[Vintage Ford Guy]

What is "tick over"? I've made my living as mechanic during the carburetor era and I have never heard of that. If were talking about "vapor lock" I have good wealth of knowledge. You have probably heard that water boils at a higher temperature at sea level and the boiling (turns into a vapor) point drops as you go up in elevation. Your car will overheat easier the higher elevation you are at. For every one pound of pressure we apply to the water we raise that boiling point 4 degrees. Inside your car's engine the water would turn to steam at 212 degrees at sea level where the atmospheric pressure is 14.7 lbs psi. For every 1000' in elevation we go up we loose about 1 lb. of pressure because there are less air molecules so at 3000' elevation your water would turn to steam at 200 degrees. When water turns to steam its volume increases by something like 1600 times and it explodes hoses, cracks engine blocks, really bad things happen. Engineers figured out that if they used a radiator cap that could hold additional pressure they could keep the water from turning to steam. A 12 lb. cap would raise the boiling point 48 degrees. You can prove this by releasing that pressure (definitely not recommended) the water immediately boils and turns to steam.

With a mechanical fuel pump you are sucking the fuel out of the tank. Instead of applying pressure to the fuel your doing the opposite, you are removing the pressure from it. That means the gas in the line can boil at a lower temperature and turn into a vapor between you tanks and pump. Your mechanical fuel pump cannot pump a vapor and your engine runs out of gas.

With an electric fuel pump in the tank, like modern cars all have. Your pressurizing the fuel between the tank and the engine making it impossible for the fuel to turn into a vapor. You also are keeping the fuel cool by having the pump in the tank where its not exposed to the heat of the engine.

If you are using a mechanical pump you want to keep the fuel line between the tank and pump as far away from heat as possible (the suction side of the pump.

On the other side of the mechanical pump the fuel is under pressure and is not as likely to boil but its also a lot hotter on the engine side of the pump so it can still turn into a vapor. At the phone company we had a lot of 4X4 Chevy Suburbans. Some of them operated down in the valley at the 1000' elevation and some worked up on the mountain at 6000' elevation, When they got to be a couple year's old we started getting complaints from the mountain Suburbans that they would quit running after they drove awhile , until they cooled down and then they would run again. Why only the mountain Suburbans? It took us awhile to figure that one. When they were new they had 6 lbs of pressure coming out of the mechanical fuel pumps. When they were two-year's old they only had 5 lbs. of pressure. That one pound of difference, at high altitude and high temperature allowed the fuel to boil into a vapor between the fuel pump and the carburetor. Down in the valley that one pound of difference in pressure made no difference. These are the kind of problems where you must understand how things work so you can use a scientific approach to solving the problem.

Carb spacers and heat shields are designed to keep the fuel from turning into a vapor in the float bowl after you have turned the engine off. For a little while the temperature of the carburetor goes up after shutting off an engine (its called a heat soak). In addition to the additiional heat you do not have new fuel coming into the float bowl cooling it down so the remaining fuel in the bowl can boil into a vapor. Carb spacers and heat shields also help keep the fuel cooler for better performance when driving but "probably" are not probably going to be a cure for a running engine that is vapor locking.

What you need to ask yourself was did the car leave the factory configured the way it is now? If it did and it worked that way at one time why would want to start modifying things trying to solve the problem. You need to find out what has changed? Fuel pressure, exhaust routed too close to fuel lines, altitude, even the octane of the gas will effect when the liquid can tun into a vapor. Was there no problem in winter but now its quitting in summer. Here in CA we have winter and summer blends, maybe that has something to do with it. Make a mental note of when this problem started happening and if nothing has changed since it did not have the problem your probably dealing with a fuel pressure problem between the pump and the carburetor.

If you are needing to wait for the engine to cool down and restart see if spraying water on the pump and fuel line speeds up the process, if it does that where your fuel is "vapor locking". You can tee in a fuel pressure gauge between the pump and carb and see what the pressure actually is. You can tee a gauge in between the carb and tank and see how much vacuum the pump is pulling.

Vapor locking was a much more common problem back when fuel octane was lower and so was fuel pressure. My Stromberg 97 carbs on my flatheads operate on only 1-2 lbs of pressure so its easier for that fuel to boil between the pump and carburetors than it would on a Mustang with 5-6 lbs of pressure.

You could also have a plugged "vented" gas cap. As the fuel gets pulled from the tank air needs to be able to go into the tank. If your tank no longer has its after driving awhile your pump won't be able to suck the fuel out, Think of your finger over the end of a straw your sucking on.

YOu can have a rubber fuel line come apart inside. It might look prefect on the outside but inside a layer of the rubber is collapsing under the vacuum of the fuel pump . That would be pretty rare.

Here is a story. A neighbor bought a used van to haul his family out to the desert fro camping and motorcycle riding. One the way there it was fine and on the way back it kept quitting. It would quit and after a while it started again and drove another 20-minutes it would quit again. It took me a couple of days o find the problem. It was running out of gas and there was nothing left it could be but something in side of the fuel tank. While they were camping the three year old son discover the gas cap removed and poured sand into the tank. Inside the tank with a screen type filter. Little by little the sand got sucked up against the screen until it was blocked and the engine died. As van sat on the side of the rode the sand gradually fell off of the screen until enough fuel could flow to drive again. I pulled the tank and took about a gallon of sand out of it. Try and find "sand dune" inside of fuel tank listed in your shop manual as a possible cause.

 

[belky]

I never knew you can set the float levels on the AVS2, I bought it new, took the car to be dyno tuned, timing etc, never touched it, before that I had the Holley 4160 & knew how to set the fuel level, the Eddy is something new to me.
I’m been trying for the few months to try to sort out the stalling, hot engine bay, the last one I found split in one of the headers & thought that I had found the problem but ohhh noooo, still the same, I think the heat is coming from the top, down through the cleaner then into the carb, I’m thinking of making 2 shields, 1 for the top of the carb where the air cleaner sits & & 1 for the bottom where the carb sits on the intake manifold, anyone done anything like this before.

 

[myfirstcar66]

The exhaust crossover on the heads and through the bottom of the intake contributes heat, no splash pan on the bottom of an intake contributes heat, aluminum spacers under carburetors hold heat, rubber or copper instead of steel fuel lines hold heat, an engine that isn't timed properly or cooling efficiently contributes heat, headers add to underhood temps, auto transmissions add heat...

 

[mike306]

I was dealing with some underhood heat two summers ago. I am running a Summit carb and added a pheno spacer but did not help. Basically, after running I could hear the fuel "boiling" in the bowls and hard starting. I narrowed it down to my electric fan/shroud restricting airflow when the fan wasn't running, basically I was seeing much less air flow to the engine compartment vs the mechanical clutch fan and tiny stock shroud. Now the car was not overheating or running hot, just not getting enough air flow towards the top of the engine - imo. I had an adjustable fan controller and tried all sorts of settings. Long story short - went back to my clutch fan and wimpy stock shroud and all is good.

 

[daveoxide]

Going along with Vintage Ford Guy's thought... my wife's 66, when I first got it running, wouldn't run for more than 15-20 minutes before it died and just wouldn't restart until you left it for a bit. It definitely felt like it was running out of fuel, so I would clean the filter, and it would fire right back up, run for a few minutes, and then poop out again. Long story short, turns out the gas tank had a lot of water mixed with the gas (but it could still burn), the problem was it rusted the crap out of the inside of the tank and I was plugging the fuel line from tank to fuel pump with rusty fuel tank bits. A thorough cleaning of the fuel line and a new gas tank allowed it to run like normal.

Fuel boiling in the carb bowls after the engine is off and heat soaked isn't inherently bad (other than causing hot start issues), but if its doing so while running, that isn't good. Even at idle, the amount of fuel the engine is consuming, the fuel shouldn't be able to heat up to the point of vaporizing. Got any pics of the engine bay showing the fuel line routing?

 

[Woodchuck]

The exhaust crossover on the heads and through the bottom of the intake contributes heat, no splash pan on the bottom of an intake contributes heat, aluminum spacers under carburetors hold heat, rubber or copper instead of steel fuel lines hold heat, an engine that isn't timed properly or cooling efficiently contributes heat, headers add to underhood temps, auto transmissions add heat...

In the "old days" we'd pack the exhaust crossovers in the intake with Reynolds Wrap. A 1/2 inch spacer isn't all that thick as far as insulation goes... any chance at running a drop base or other style air cleaner to get a 1 inch under the carb? Also, they make a 9-ply aviation plywood in 3/4 inch... a "sandwich" of that between two 1/8 inch plates would be a possible solution as might a "turkey pan".

 

[belky]

Ok guys, 1 other thing I haven’t tried yet is an electric fuel pump, I have re routed the fuel line, it now runs from the mechanical pump in front of the radiator, up past the battery, the into the passenger side of the carb, a slight improvement to the length of time it runs before cutting out.
Does anyone think by using an electric pump might be a good option.
Or Evan swapping the AVS2 for the Holley 4160 ?

 

[daveoxide]

How does the fuel line from pump to tank look? Is it wrapped around the exhaust pipe anywhere? Or maybe a small leak somewhere (not necessarily leaking gas, but rather sucking in air)? You could try disconnecting the fuel line inlet to the pump (make sure you can plug that line) and then put a temporary hose on it going to a can of gas. Fire it up and see how long it runs like that... that would take the gas tank and supply fuel line out of the equation.

Any chance your engine oil level is increasing? Does the engine oil smell like fuel?

 

[belky]

I’m pretty sure all the fuel lines are good & are away from the exhaust.
any thoughts on the AVS2 against the Holley 4160

 

[P-51]

I never knew you can set the float levels on the AVS2, I bought it new, took the car to be dyno tuned, timing etc, never touched it, before that I had the Holley 4160 & knew how to set the fuel level, the Eddy is something new to me...

Two good sources of info:

(1) The manual which tells you how to set the float level (page 8). IMO, this manual is well written and worth reading regardless of what carb you have.as it goes somewhat in depth on how generally carbs work.

https://www.edelbrock.com/pub/media/wysiwyg/documents/carb-owners-manual.pdf

(2) Youtube. Lots of videos on how to setup and tune edelbrocks. Some good examples

(3) And an interesting video on a possible solution to severe vapor lock

 

[Woodchuck]

I have re routed the fuel line, it now runs from the mechanical pump in front of the radiator, up past the battery, the into the passenger side of the carb, a slight improvement to the length of time it runs before cutting out.

Which means you must have rubber hose from the pump to the carb. Therein probably lies most of your problem. Rubber hose won't let the fuel inside it release heat. Rubber is an insulator. The fuel will keep getting hotter and hotter. You need a steel line from the pump to the carb. Get one of the Edelbrock inlet tube/filter kits and steel line.

 

[belky]

Your right I have, good shout woodchuck, what other fittings would I need to connect to the mechanical pump, & the fuel filter end.

 

[belky]

Which means you must have rubber hose from the pump to the carb. Therein probably lies most of your problem. Rubber hose won't let the fuel inside it release heat. Rubber is an insulator. The fuel will keep getting hotter and hotter. You need a steel line from the pump to the carb. Get one of the Edelbrock inlet tube/filter kits and steel line.

Thanks for the advice Woodchuck, I’ve tried a temporary steel fuel line from a can in front of the car, had the car running hood down for a good 35-40 minuets, your right with the steel fuel lines,
Now what I’m wanting to do is run a steel fuel line from the mechanical pump to the carb, I’m happy with the inlet tube & filter kit, but what other fittings do I need to make the connection to the pump.

 

[HarryZ]

There was another thread here that referenced finelines.com (which seems to nowadays route you to sstubes.com) having the fuel supply line for the SBF with an Edelbrock carb, but when I search their site I don't find it. Maybe you can contact them and see if they can / will produce this line.

Harry Z

 

[belky]

I’m ok with making the line myself, I have the tools needed, I just don’t know what fittings I need to buy to connect to the pump outlet up to the fuel filter. If someone could point me in the right direction on what fittings to buy.

 

[Woodchuck]

I’m ok with making the line myself, I have the tools needed, I just don’t know what fittings I need to buy to connect to the pump outlet up to the fuel filter. If someone could point me in the right direction on what fittings to buy.

A stock-type pump to carb fuel line will probably work. At the carb end, just cut off the "hose barb" and use a 5/16" tube to -6AN adapter for the Edelbrock filter & inlet kit like the one below...

Earl's AT165156: Ano-Tuff Hard-Line to AN Adapter Fitting -6AN Female to 5/16" Tube | JEGS

 

[belky]

Thanks Woodchuck, really good advice I now know the parts I need to make a complete hard line from the pump to the carb,
Just had a quote from Jeggs, $71.00 for the parts & the best bit $171.00 p&p to the UK. So I don’t think I’ll be buying anytime soon, none in the UK that I can find, so I’m stuck for the time being.