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  #11  
Old 03-21-2012, 03:03 PM
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no bribes necessary..
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Old 03-21-2012, 08:46 PM
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I installed my header, along with the liquid heat riser and it works great. If you install a header and don't get even small power gains and you lose MPG, then it's because you didn't re-jet the carb after installing the header.

I also didn't have to go to any extremes to get my header to seal up without leaks. Just used a standard gasket and made sure I torqued it up evenly then hit it again when it was really hot.

It's a matter of personal choice, especially since you already have the header. Pull off the manifold and give the header a try. While you're doing that, get the manifold fixed, that way you can always swap back if you want.
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  #13  
Old 03-23-2012, 04:13 PM
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Default Thanks everyone (esp. marco). header is in future.

I think I'll take the plunge and get rid of all the smog stuff and Header-it. So for now, I'll be getting ready for CM12 and research fluid heat risers and the right gasket as well as how to set the carb and dizzy.

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Old 03-24-2012, 08:43 AM
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The liquid heat riser is a must have with a header IMHO. It will make it warm up nicely when it's cold and keep it from vapor locking when it's hot. You can buy one as a kit or you can make your own. You just need a square piece of thick plate (the kit ones are aluminum but steel would work if you powder coat it) drill 4 bolt holes to match the bottom of the intake then drill & tap 2 holes that you screw 90* right angle fittings into. These are for the in-out flow of coolant. Make sure you put an air bleed into the heater hose at the highest point near the firewall and you're ready to go.
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Old 03-24-2012, 09:01 AM
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Quote:
Originally Posted by Air Randy View Post
The liquid heat riser is a must have with a header IMHO. It will make it warm up nicely when it's cold and keep it from vapor locking when it's hot.
Randy, I'm not running a liquid heat riser with my header. I've never had a problem with cold starts BUT I've had several instances of bad vapor lock when hot. How does the heat riser prevent it? Think I might try adding one if it will help with the vapor lock issue.
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Old 03-24-2012, 09:17 AM
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The heat riser passes coolant right under the intake manifold and moderates the temperature of the intake manifold and carb. It really is functionally the same purpose as the flap in the OEM exhaust manifold; at cold temps send additional heat to the intake/carb and at hot temps keep additional heat from the intake/carb - it just does this using the engines cooling system.

With a hot truck, the coolant draws heat from the intake manifold and carb which helps keep the fuel from turning to vapor. I had vapor lock on the 40s only run when I was not using the fluid heat riser, since installing it I have not had a any vapor lock.

With cold starts, as the coolant warms up, the heat is transferred to the intake manifold and carb which helps the fuel and air atomize more effectively. Cold fuel does not like to mix with air as well as warm fuel.
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Old 03-24-2012, 10:30 AM
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Thanks for the explanation Ricardo. Makes sense. Now I need to look at my manifold and figure out what I need.
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Old 03-24-2012, 11:13 AM
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You're partially correct and definitely on the right track. However what is happening when the manifold is cold is the fuel is atomized as it is pulled from the carburetor by the air passing through but when it gets to the cold intake manifold and has to do a 90 degree turn it slams into the manifold and condenses from the cold and puddles up there.

The exhaust manifold is far more effective at combating this because it heats the intake much faster than waiting for water to heat up while the pooled up fuel hurts your emissions and sneaks past your rings when it gets to the combustion in liquid form thereby washing oil off the cylinder walls and contaminating the oil in the crankcase.

Vapor locking, by definition, does not occur to cold fuel. It is a result of hot fuel boiling and turning to "vapor". I'm not sure what you are experiencing when your truck is cold but it is not vapor lock. Perhaps you are experiencing an overly rich mixture caused by what I explained before.

If you simply must use a header (like I did before I knew better) the liquid heaters are better than nothing but it will never be as effective as a manifold and you WILL see increased wear from the overly rich condition before the water gets warm enough to have an effect. It may be academic but a fact just the same.

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Old 03-24-2012, 03:04 PM
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The exhaust manifold is far more effective at combating this because it heats the intake much faster than waiting for water to heat up while the pooled up fuel hurts your emissions and sneaks past your rings when it gets to the combustion in liquid form thereby washing oil off the cylinder walls and contaminating the oil in the crankcase.

Vapor locking, by definition, does not occur to cold fuel. It is a result of hot fuel boiling and turning to "vapor". I'm not sure what you are experiencing when your truck is cold but it is not vapor lock. Perhaps you are experiencing an overly rich mixture caused by what I explained before.

If you simply must use a header (like I did before I knew better) the liquid heaters are better than nothing but it will never be as effective as a manifold and you WILL see increased wear from the overly rich condition before the water gets warm enough to have an effect. It may be academic but a fact just the same.
Sorry, but I don't agree with you. First off, every carbed V8 engine in the world relies on either the water heating up or thermal transmission via the metal to metal contact with the cylinder heads to warm up. They have many more intake runners and bends than a 2F does. They have no more issue with emissions or cylinder scoring from wash down than any other engine. Very few engines have the exhaust manifold bolted directly under the intake & carb.

Also, even if you do get a miniscule amount of liquid fuel in a cylinder, it only lasts until the first time that cylinder ignites. Any that does get into the oil usually evaporates out of the oil and is ingested into the intake via the crankcase vent valve. I routinely do oil testing via Blackstone on my 2F with a header and my fuel content in the oil is always less tha 1%, up to 3% is acceptable.

Ricardo is not saying his truck vapor locks when it's cold. He is saying that by having the liquid heat riser wick the heat away from the bottom of the intak/carb, it prevents it from ever getting hot enough to boil and cause vapor lock.
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  #20  
Old 03-24-2012, 04:46 PM
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I mean no disrespect, however some of the stuff reported here has some flaws.

A V8 engine, with a few exceptions (Ford FE comes to mind) do not have a sharp 90 degree bend before the valve such as the 2F. And you forget the exhaust crossover on most factory intake manifolds whose job it was to heat the intake. Not to mention the hot oil that splashes the underside of a lot of V configuration engines. I never stated the fluid heat riser didn't work, I stated it is less efficient (slower) than the factory exhaust manifold. It is a band-aid. I have used them and yes they are better than nothing but they are less than ideal. However the 2F was not designed to be pinnacle of automotive engineering and comes with MANY inherent flaws, the intake arrangement being just one of them.

Also, liquid gas isn't ignitable by spark. It must be converted to vapor or atomized. That is the function of the carburetor. If you doubt that then refrigerate some gas in a cup so that it is not giving off vapor and throw a match at it. Yes you can put a match out in liquid gasoline. It must be properly atomized to burn correctly. If liquid fuel makes it to the combustion chamber it will not be burn correctly and has the potential to wash the oil off the cylinder walls and contaminate the oil in the crankcase. I also stated that the amount may be academic and it depends on the condition of the rings. When enough liquid gas makes it to the cylinder to wash oil off the walls it will increase the wear. Again, this may be academic.

I did misread what MDH33 stated about vapor locking while cold. I read it too fast. My apologies.
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