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Old 01-25-2013, 09:26 PM   #1
jhngardner367
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Vapor lock cure for carbed engines

I'm making a "cool-can" for my '87 c10,because I was tired of having vapor-lock on hot days.
It is basically like the old style ,except it doesn't use ice in the can . It's a sealed unit,much like a miniature cooling system for the engine,and uses DEX-COOL.
I hope to have it done in the next few days,and I'll take pics as I go,so others can try it. I made one, last summer,for my cousin's truck(his was doing the same thing),and it seems to have cured the problem.
He has 8k miles on it,after driving to Arizona,and he says it never locked once.
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Old 01-25-2013, 11:10 PM   #2
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nice I always wanted to try something like that or run a small trans cooler but since my current engine required the use if a electric pump I've not had any vapor lock issues. post pics when your done curious how it comes out


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Old 01-26-2013, 09:47 AM   #3
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Re: Vapor lock cure for carbed engines

With the fuels becoming more and more diluted with alchohol, the vapor lock issues will grow. Especially in the carb bowls.
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Old 01-26-2013, 05:07 PM   #4
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Re: Vapor lock cure for carbed engines

The way it's designed,it should help.
the "cool-can" is not cooling the fuel,as in most. It holds the coolant,which circulates through a plate that the carb sits on(basically an insulator plate),and keeps the fuel from reaching boiling point.
It is a simple thing to make,and has worked well on my cousin's truck,so, I'll try it on mine,and,this time,I'l take pics,as I build it.
Right now,I'm waiting for some materials I ordered,to get here.
I'll keep you posted.
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Old 01-26-2013, 05:57 PM   #5
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Re: Vapor lock cure for carbed engines

Seems like a funny time of year for a guy from Michigan to be concerned about vapor lock?
While I can see your under-carb being a cool thing, I'm not convinced that it is the "cure" for vapor lock problems. Bowl boiling is not the only source. Many times the lines to and from the fuel pump on the side of the block are the blockage.
As far as I can see, an electric pump near the tank is the best cure.
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Old 01-26-2013, 07:47 PM   #6
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Re: Vapor lock cure for carbed engines

That is true,however,I've already changed to an electric fuel pump,and insulated the lines.
I'm more worried about the fuel boiling out of the carb,at this point.
I tried the standard plate under the carb,and,though it did help,it still boiled out on hot(78f+) days,especially in traffic.When I made the one for my cousin's truck,it wasdoing the same thing,but now,with the mods,he hasn't had any problem. He used the truck in July,in Tucson,AZ,and he was happy with it!
It can't hurt,right ??
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Old 01-26-2013, 08:14 PM   #7
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Re: Vapor lock cure for carbed engines

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,it still boiled out on hot(78f+) days
No offense, but...




Seriously, 78 degrees F is not by any stretch of the imagination a hot day. If you are getting symptoms of what you think are vapor lock on a day like that then there is actually some other issue going on.

Half the laughter comes from my having lived 95% of the year these days on either the gulf coast in New Orleans/Mobile areas or around Atlanta for the past 7-8 years now... 78* hot... leading to vapor lock...

honestly, there is something else going on there that shouldn't require custom aftermarket setups if you think you get vapor lock on a cool day like that.
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Old 01-27-2013, 03:10 PM   #8
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Re: Vapor lock cure for carbed engines

NOT REALLY. You see,a lot of the driving is in temps that are 78 PLUS(meaning higher)temps,in heavy city traffic,and pulling loads. SO,YES, it does occur,and quite frequently,with the E-10 fuels.
At times, (such as last summer) we can reach temps of 90-100 f.,so laugh all you want...at 61 yrs old, I don't feel like setting along the road,in the heat !
Also,I am moving to ARKANSAS,in a couple of months,which,as you MAY know has a LOT higher temps,and I want to be sure the problem is gone!
Oh,and by the way...E-10 fuels will boil at lower temps,and only have a shelf life of 100 days. Also,anything more than .5% of water in it,can render E-10 ethanol fuels unusable ! That's only 4tbsp,per gallon !
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Old 01-27-2013, 04:02 PM   #9
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Re: Vapor lock cure for carbed engines

I actually use water to take ethanol out if my fuel it soaks all the Ethonal up and leaves you with pure gas. Add octan booster to get it back up to snuff and you get your ten percent power back.

Also running a return line style fuel pump kills all vapor lock issues. If you still getting vaor lock your fuel is either perculating in the bowls or your intak is way to damn hot and your carb os over atomizing the fuel along with to much heat. As well as if your exhaust is making your fuel lines to hot then that's an issue as well.
A carb spacer will help cool the carb and making restrictors for the exhaust crossover with coke can run helps. As will fuel line insulation and better routing and a cool can as a last resort
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Old 01-27-2013, 04:28 PM   #10
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Re: Vapor lock cure for carbed engines

My truck had vapor locked once. It was my fault at that. For some reason I decided to prime the carb engine warm. Didn't get to far lol. I would let the truck run for 1-2 minutes to get the carb cooled by the fresh gas. Where are you moving to in AR?
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Old 01-27-2013, 07:10 PM   #11
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Re: Vapor lock cure for carbed engines

Ive never had vapor lock ever on either of my trucks even in the summer when its 90-100 degrees in July and August. I just have normal mechanical fuel pumps on both. You must have something wrong thats causing this. I agree try carb spacer and make sure exhaust isnt heating fuel lines etc. Something is wrong with your setup thats causing this.
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Old 01-28-2013, 10:21 AM   #12
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Re: Vapor lock cure for carbed engines

Lots of things cause vapor lock, and there are ways to prevent it.

In Michigan this time of year isn't unusual to see vapor lock if you have one of those unusually warm winter days. I lived in Ohio and know how flip flop the weather can be.

During winter months they use what is called a winter grade fuel to prevent fuel line freeze up. The problem with it though is the additives used cause major vapor lock headaches when the temp even reaches 50 degrees. To top that off, they don't switch back to summer grade fuels until April when areas like Michigan, Ohio, Indiana can already see temps in the 60's or more. Top it off with a continually degrading quality of fuel with 10% (or more) of ethanol added and it compounds the problem. A real pain in the ass.

Things you can do to battle vapor lock...

Biggest and most effective.....Run a return style fuel system. By 1971 this became pretty much standard issue on most vehicles so you should have it on your truck. This keeps the fuel moving in the fuel lines (up to the pump at least) so it isn't sitting stagnent in the system and attracting heat. The only stagnent fuel in the system with a return style fuel pump is the line from the pump to the carb.

Make sure the line from the pump to the carb isn't touching anything. At least a fingers width from things like the cylinder head, water pump, thermostat housing, intake manifold etc....

Run a higher octane fuel. You spend more at the pump, but the lower octanes have such a low flash point they are more susceptable to vapor lock.

Run a heat shield under the carb if you wish. This will slow down the process of radiant heat reaching the carb.

I also use a thick carb gasket (not the paper thin junk) Usually 1/4" thick, can be found in any parts stores. This will help as a mild heat soak.

If you can get away with it, I block off the heat risers to keep the intake manifold cooler. Worked fine for me while living in Ohio even during cold months. Does make some cars finicky however on cold start up.

I also prefer to run a cooler thermostat. Keeping the engine cooler means cooler underhood temps.

With all of these little tricks done, you really shouldn't have a vapor lock issue. I don't see it even in 110 degree heat here in AZ with crap gas, no fancy cool cans either.

If you run an electric pump, vapor lock becomes a non issue, because they push fuel much better and usually at higher pressures that require a regulator.... Stock mechanical pumps suck fuel and generally are lucky to generate 6 psi of pressure.
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Old 02-05-2013, 06:18 PM   #13
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Re: Vapor lock cure for carbed engines

I just got home from my son's school. I was stuck there for two hours because of vapor lock. Today is the warmest day, a whopping 75 degrees, I have driven the truck since we put it back together. I am going to order a Phenolic spacer to replace the aluminum thats on there. Here is a picture of the fuel line.
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Old 02-05-2013, 06:28 PM   #14
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Re: Vapor lock cure for carbed engines

Quote:
Originally Posted by jhngardner367 View Post
NOT REALLY. You see,a lot of the driving is in temps that are 78 PLUS(meaning higher)temps,in heavy city traffic,and pulling loads. SO,YES, it does occur,and quite frequently,with the E-10 fuels.
At times, (such as last summer) we can reach temps of 90-100 f.,so laugh all you want...at 61 yrs old, I don't feel like setting along the road,in the heat !
Also,I am moving to ARKANSAS,in a couple of months,which,as you MAY know has a LOT higher temps,and I want to be sure the problem is gone!
Oh,and by the way...E-10 fuels will boil at lower temps,and only have a shelf life of 100 days. Also,anything more than .5% of water in it,can render E-10 ethanol fuels unusable ! That's only 4tbsp,per gallon !
What part of Arkansas you moving to? if its in the ozarks (where i am) like here in Thayer Mo. the weather changes on a dime. the summer is upper 90`s and lower 100`s most of the time but its muggy and nasty really heavy damp hot air. so 95 feels like 105 ive had issues with vapor lock on some trucks and my buddies 49 ford custom. so its definitely a good idea. can`t wait to see how you do it. i just might steal it
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Old 02-05-2013, 06:50 PM   #15
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Re: Vapor lock cure for carbed engines

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I just got home from my son's school. I was stuck there for two hours because of vapor lock. Today is the warmest day, a whopping 75 degrees, I have driven the truck since we put it back together. I am going to order a Phenolic spacer to replace the aluminum thats on there. Here is a picture of the fuel line.
Edelbrock carbs are the worst at fuel percolation btw. Spacer and heat shield will be a good idea
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Old 02-05-2013, 06:53 PM   #16
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Re: Vapor lock cure for carbed engines

Your problem doesn't sound like vapor lock.
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Old 02-05-2013, 07:21 PM   #17
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Re: Vapor lock cure for carbed engines

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Originally Posted by fatgump View Post
I just got home from my son's school. I was stuck there for two hours because of vapor lock. Today is the warmest day, a whopping 75 degrees, I have driven the truck since we put it back together. I am going to order a Phenolic spacer to replace the aluminum thats on there. Here is a picture of the fuel line.
Edelbrock carbs will give you fits with heat soak, and that Edelbrock mechanical pump doesn't have provisions for a return line, something desperately needed using todays fuels.

I see quite a few things that would help you but that's two bigger ones. Just to add, anything shiny and chrome in the fuel system attracts heat.
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Old 02-05-2013, 07:48 PM   #18
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Re: Vapor lock cure for carbed engines

Thanks for the input. I used the search for vapor lock and instantly posted a reply, assuming this was in the engine section. I didn't mean to hijack. I am going to repost this in the engine section. Thanks.
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Old 02-06-2013, 11:01 AM   #19
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Re: Vapor lock cure for carbed engines

Is you fuel line laying against the water pump?
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Old 02-06-2013, 11:46 AM   #20
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Re: Vapor lock cure for carbed engines

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Edelbrock carbs will give you fits with heat soak, and that Edelbrock mechanical pump doesn't have provisions for a return line, something desperately needed using todays fuels.

I see quite a few things that would help you but that's two bigger ones. Just to add, anything shiny and chrome in the fuel system attracts heat.

I agree on the fuel line return and the Edelbrock fuel pump. I tried to put one in without the return on my 84 truck and that was a painful experience with vapor lock. I reinstalled the return, by buying the bottom piece for the fuel pump that allows numerous outlet ports and installing the return line again. I also put the phenolic spacer on and ninety percent of the problems left.
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