vapor lock / overheating on '68 383

[cougs]

Hello!  First time poster here.

My name is Brock and am the proud owner of a 1968 Charger with a 4bbl 383/727/3.23 open 8 3/4.......My dad bought this car in 1970 and we restored it from 1993-1998. 

Ok, so the car had been running great except for two problems.....#1 --- overheating!!  The engine has been rebuilt and we had the radiator recored (22" with no shroud).  I recently had the radiator cored again with a high efficiency core and it seems to have helped but can still creep above 180 to about 210 at a stoplight on a hot day.  Timing appears fine and it doesn't appear to be running lean.  Any help would be appreciated.

Now for the problem I had today.....It was about 90 degrees in Yakima, WA today and the charger was running fine on my drive home.  Ran it on the freeway for 10 minutes then started up a long hill on the way home in a 30 mph zone.  The engine starts sputtering and died.  Immediately knew it was vapor lock and let it cool for 30 minutes and after 2 minutes of cranking it finally started right up.  It seems like ALL of the fuel in the line from the tank was gone.  Is this possible?  The car was still running at 180/190 degrees, but man, that air cleaner was hotter than blazes when I took it off!!!  The fuel line is all stock.  The metal line is touching one of the heads so I will adjust it to see if that helps.  Other than that what can I do?  I read some archives and it seems that blocking the heat crossover is an option.  I don't want to use a spacer just for originality/appearance (plus, will the choke linkage from the intake still work with the spacer?).

Thanks in advance for any advice!!! (here's a pic)

[Brock Samson]

 

with a car that pretty i'd be happy to just sit there and let it cool off,.. 

seriously, though mine did that alot.. when i finnaly got a three core Rad. it stopped,. one trick i heard was to attach a simple clothes pin to the fuel line,.. i think the idea behind that was the spring acts as a heat sink,.. but that's not a real solution...

my charger hasn't over heated since i had a small block in the '90s... i'd suggest a fan shroud,.. it's an easy part to get and should help..

welcome to the best site on the web!

[Kevin68N71]

Just some suggestions.

Replace your thermostat if it has any age at all on it.

Borrow/buy a pressure tester and check for any leaks--you can have a small one that burns off fluid pretty quickly.

Replace your cap if you have any age on it.  This just happened to my Super Bee...started running warm WITH the new radiator---took a close look at the cap and saw it was no good anymore.  No problem since.

Check your timing, on some cars running too advanced can cause problems.

Replace your hoses if they are old.  Old hoses can "suck closed" during driving...then when returning to idle and you get out and check, they are not crimped closed anymore!  Make sure your clamps are good condition and tight.

And I hope you are not doing anything crazy like NOT running a thermostat at all (water with no regulation runs through the system so fast that it might not transfer heat out at all) or running straight water.

Just some easy to overlook considerations.

One other thing, on Mopars you typically have a fuel line that is rubber all the way (vs. GM cars that often have carefully routed steel tubes over the engine.  Keep that fuel line cool!

A buddy of mine has a Charger and his fuel line was nowhere near the exhaust manifold, but it did route OVER it.  After a drive, I grabbed the fuel line and it was HOT.  This is not only dangerous, but it sure doesn't help the car run well.

The Mopar fuel pump placement sucks--under the alternator with the line coming out facing your belts.  I have seen guys go to the left (facing the car), up and over to get to the carb, and all different ways.  That route takes you, again, over the manifolds.

Carefully route your fuel line to avoid strong heat sources.

[skip68]

   Welcome Brock.  Love the car.       Do you have a return line ?   This seems to be a problem with lots of cars today because the fuel today has a lower boiling point.   My car runs about 190 degrees and I've been told that's ok.  My car does the same thing and a shop here in Vegas told me they have had this problem with several of the classic cars motors this last two years.  The guy at the shop said once they added an electric fuel pump and a return line the problem went away.   I bet you have a strong gas smell when this happens too don't you ?   Good luck.     Chuck............

[69ChargerNut]

Without a shroud the fan will pull most of its air in from the sides rather than through the radiator which can easily cause over heating especially when you're using a 22" radiator.

[mjwebb]

I've taken the good advice from the experienced and knowledgeable folks on this site and put a hard fuel line on, a metal fuel filter and a heat dissapaiting carb gasket on and my 70 383 starts much better when hot, runs around 200 degrees on a hot day and I don't currently have a shroud...but the car runs very smooth, no vapor locks and doesn't ever die....I'm calling it good except for replacing my stock cast manifold with an aluminum edelbrock performer

[Sublime/Sixpack]

Do what skip68 suggested. I had a problem with my '69 Bee vaporizing the fuel until I upgraded to a 440 fuel line set up (supply line, return line, fuel seperator, fuel sending unit, etc.).

[69*F5*SE]

Welcome Brock, your Charger is beautiful.    Lots of good suggestions here.  I'm certain it will help. 

[GN]

Could the lower radiator hose be missing the spring?

[cougs]

Thanks for all the ideas!  How do I add a return line?  Is there a kit to do that? 

Also, I would like to add a shroud but the radiator I have doesn't have any provisions (brackets) for a shroud.  I bought a shroud and hardware once for the car but it was fiberglass and the hardware simply wouldn't work.  This is a 22" radiator.

Also, after further investigation my fuel line is not touching the block or the head on the 383.  I don't see where it is picking up heat in the line. 

Thanks for the help!

Brock

[NHCharger]

 check to see how close your fuel line is to your exhaust manifold.
How much space do you have between the fan and radiator?

[firefighter3931]

Nice car and welcome to the site. 

Looking at your engine pics it's easy to see the paint that is burnt off the intake manifold at the heat crossover. This is a common issue that contributes to the dreaded vapor lock. Felpro makes an intake gasket that blocks this crossover off and keeps the manifold cooler. The carb also needs a thick "insulating" base gasket. These are usually 1/8in thick and work quite well at reducing conductive heat.

The overheating issues can contribute to vapor lock so check your timing. If the carb is jetted too lean this will also contribute to overheating.



Ron

[cougs]

Thanks for help everybody,

NHCharger: The fan is about an inch away from the radiator.  Should I try to find a spacer to get it closer?  The fuel line is a ways from the manifold and about 1/4" away from the passenger head.  I'm going to move it away from the head.  Other than that, that's the only heat source near the fuel line. 

Ron: Thanks for the suggestions.  I have the intake gasket on the to-do list (has been because the burn paint ticks me off).  I'm going to give the 1/8" intake gasket a try.  My plugs are paper bag brown so I thought my burn was pretty good but may remove the carb and try the next richer jet when i'm doing the intake.  As for timing, If I remember right I have it at 5 btc? which is about as advanced as I can go before it pings.  I'll try 4/3 btc and see if that helps bring down the temp. 

Brock

[Hemidog]

post some more pics of it on the charger pics thread! 

[firefighter3931]

Thanks for help everybody,

NHCharger: The fan is about an inch away from the radiator.  Should I try to find a spacer to get it closer?  The fuel line is a ways from the manifold and about 1/4" away from the passenger head.  I'm going to move it away from the head.  Other than that, that's the only heat source near the fuel line. 

Ron: Thanks for the suggestions.  I have the intake gasket on the to-do list (has been because the burn paint ticks me off).  I'm going to give the 1/8" intake gasket a try.  My plugs are paper bag brown so I thought my burn was pretty good but may remove the carb and try the next richer jet when i'm doing the intake.  As for timing, If I remember right I have it at 5 btc? which is about as advanced as I can go before it pings.  I'll try 4/3 btc and see if that helps bring down the temp. 

Brock

Brock, your engine will want more than 5*btdc for base tming. What happens is basicly this ; retarded timing doesn't allow the fuel to burn in the combustion chamber because of the "late" timing. The unburnt fuel ends up igniting in the exhaust manifolds and creates tons of heat in the headers/manifolds and under the hood. The lazy timing curve will often lead to overheating problems.

The problem with advancing the base timing is that it also increases the total timing which can lead to pinging. The answer is to limit the mechanical advance so that the combination of your base timing and mechanical advance falls within the desired area. Often the vacuum cannister will pull lots of extra timing into the engine and cause preignition so that's why i never use them.

Try this : bump the timing up to 12-14* and block off the vacuum advance. Map out the timing curve in 500rpm increments and report back. Ideally you would like to see no more than 36-38* total timing all in at 3000 rpm or less.



Ron

[375instroke]

Vacuum advance should always be on a street car.  You want all that extra timing under light load.  It goes away when you increase manifold pressure, right.  I don't understand how metal fuel lines, fuel filters, and clothes pins help anything.  Wouldn't they act as a heat sink from the hot engine compartment into the fuel, not away from it?  How would a few degrees of retarded timing cause fuel to burn in the exhaust manifold?  What happens when you install a cam just a few degrees bigger than stock?  How big is your cam anyways?  Is it stock?  My 440 has the original 22" radiator and the previous owner shit canned the vapor separator (idiot), so the return line isn't hooked up.  Record temperatures here in Washington, as you have experienced, and no problems with overheating or vapor lock.  I'm sure the shroud makes a big difference, and the 1" fan to radiator clearance is the maximum.  I like setting timing for the max setting with vacuum advance disconnected, and use lighter springs to increase initial.  The factory used stiff springs to reduce low RPM timing, thus reducing HC emissions.  I had a problem with air in the system causing a motor I rebuilt to geiser after 2 or 3 minutes of running due to air trapped in the motor.  A #40 hole drilled into the thermostat helps with this problem, or tun the motor without one for a while to purge the air.  Low fuel pressure could cause the vapor lock.  Mopar had 3 different fuel pressures in their big blocks.

[Chryco Psycho]

I have to disagree , you can clearly see the exhaust temp is too hot from the burned paint on the crossover port , stick an allen wrench in the vacuum advance & turn it counterclock wise about 12 turns or better yet disconnect the vacuum advance & get the timing up in the 12-16 * range at idle & the heating prob will disappear